APHIS Evaluation of the

Classical Swine Fever

Status of a Region

in Mexico 

October 2013

United States Department of Agriculture

Animal and Plant Health Inspection Service

Veterinary Services

National Center for Import and Export

Regionalization Evaluation Services
Evaluation of the CSF Status of a Region in Mexico October 2013

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Table of Contents

List of Figures, Tables and Appendices............................................. ..............3

Abbreviations............................................. ........................................................4

Executive Summary...........................................................................................5

Introduction......................................................................................................11

Hazard Identification ............................................................................15

Release Assessment ...............................................................................18

Scope of the evaluation ....................................................................18

Veterinary control and oversight ..................................................... .18

Disease history and vaccination practices ............................................23

Livestock demographics ........................................................ ..........31

Epidemiological separation from potential sources of infection ..................36

Diagnostic laboratory capabilities .....................................................42

Surveillance practices ........................................................ ..............43

Emergency preparedness and response ...............................................50

Release assessment conclusions ......... ................................................51

Exposure Assessment .......................................................................... 57

Consequence Assessment ...................................................................... 59

Risk Estimation ..................................................................................63

References .........................................................................................64

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List of Figures

Figure 1: APHIS Regionalization of Mexico for CSF .....................................................12

Figure 2: Structure of State Veterinarian Service.............................................................21

Figure 3: Epidemiological Status National CSF Campaign, 2005 ..................................28

Figure 4: Epidemiological Status National CSF Campaign, 2008 ..................................28

Figure 5: Swine movements into and out of Central Western Region, 2011 ..................33

Figure 6: Swine movements into and out of Chiapas, 2011 ............................................35

Figure 7: Phyto and Zoosanitary Quarantine Lines .........................................................40

List of Tables

Table 1: Significant Dates for the CSF Campaign in Mexico ......................................... 24

Table 2: Swine Production by State, 2011........................................................................ 31

Table 3: CSF surveillance sampling scheme, 2011 ......................................................... 45

Table 4: CSF surveillance sampling scheme, 2012 ......................................................... 46

Table 5: Active CSF surveillance samples with positive findings, 2011-2012 ................47

Table 6: Passive CSF surveillance samples with positive findings, 2011-2012 ...............48

List of Appendices

Appendix 1: Certification of the Centro de Palo Alto Laboratory as CSF Diagnostic Reference Laboratory 

in Mexico, November 28- December 1, 2011..............................................................A-1

Appendix 2: SENASICA Organization Chart..............................................................A-8

Appendix 3: Mexico CSF Case Definition..................................................................A-10

Appendix 4: Mexico CSF Site Visit Report: Field Investigations of CSF Suspect Farms in the State of 

Guanajuato, November 14-18, 2011............................................................................A-18

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Abbreviations

APHIS Animal and Plant Health Inspection Service

CPA Comision Mexico-Estados Unidos para la prevencion y control de la 

fiebre aftosa y otras enfermedades exoticas (Mexico-USA Commission 

for the Prevention of Foot and Mouth Disease and other Foreign Animal 

Diseases)

CENASA Centro Nacional de Servicios de Diagnostico en Salud Animal (National 

Veterinary Services Diagnostic Laboratory)

CENAPA Centro Nacional de Servicios de Constatacion en Salud Animal (National 

Veterinary Toxicology and Parasitology Laboratory)

CFPP Comité Estatal Para el Fomento y Protección Pecuaria de Nayarit, S.C.

(Animal Agriculture Promotion and Protection Committee) 

CSF Classical swine fever

CWR Central Western Region

DGICA Direccion General de Inocuidad y Calidad Agroalimentaria (General 

Directorate of Agrifood Safety and Quality Control)

DGIF Direccion General de Inspeccion Fitozoosanitaria (Animal and Plant 

Health Inspection Service General Directorate)

DGSA Direccion General de Salud Animal (General Directorate Animal Health)

DINESA Dispositivo Nacional de Emergencia de Sanidad Animal (National Animal 

Health Emergency Operation) 

GEESA Grupos Estatales de Emergencia en Salud Animal (State Animal Health 

Emergency Group)

NOM Normas Oficiales Mexicana (Official Standards of Mexico)

SAGARPA Secretaria de Agricultura, Ganaderia, Desarrollo Rural, Pesca y 

Alimentación (Ministry of Agriculture, Livestock Production, Rural 

Development, Fishery, and Food)

SENASICA Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria

(National Service of Agrifood Health, Safety and Quality) 

TIF Federal Inspection Type Establishments 

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Section 1. Executive Summary

In November 2007, the Government of Mexico submitted a request to the Animal and 

Plant Health Inspection Service (APHIS) seeking recognition of the classical swine fever 

(CSF) status of the States of Aguascalientes, Colima, Guanajuato, Jalisco, Michoacán, 

Querétaro, San Luis Potosí, and Zacatecas to allow export of fresh pork and pork 

products originating in these States to the United States. Collectively, these States are

known as the Central Western Region (CWR) [1]. Mexico had declared these States free 

of CSF in July 2006 after conducting a CSF eradication campaign. On receiving this 

request, APHIS initiated an evaluation of the CSF status of the CWR (see Figure 1, page 

11). In September 2008, the Government of Mexico expanded its request to include 

evaluation of the State of Puebla, which had been declared CSF-free in December 2006. 

In 2009, Mexico expanded its request to include all Mexican territory after its January 30, 

2009, declaration that the entire country was CSF-free. 

APHIS technical teams made two site visits to the CWR, the first in May 2008 and the 

second in April 2012. In December 2012, APHIS conducted a site visit to evaluate the 

remaining unrecognized States of Mexico. The results of these evaluations allowed

APHIS to decide whether to recognize the disease status and under what conditions to 

accept the importation of fresh pork and pork products originating from additional 

regions in Mexico.

Supporting documentation reviewed for this risk assessment came from the Secretaria de 

Agricultura, Ganaderia, Desarrollo Rural, Pesca y Alimentacion (Secretariat of 

Agriculture, Livestock, Rural Development, Fisheries and Food, or SAGARPA) and 

Mexican State governments; observations made by APHIS technical teams during site 

visits in May 2008, April 2012, and December 2012; peer-reviewed articles; and data 

from the World Organization for Animal Health (OIE) and other technical sources.

This risk analysis was conducted according to OIE guidelines and therefore includes a 

hazard identification section, a release assessment, an exposure assessment, a

consequence assessment, and a risk estimate [2]. The hazard under consideration is CSF

virus. 

Release Assessment

Serologic evidence of exposure to CSF virus has been found in a number of Mexican 

States. The specificity of the antibodies was demonstrated by comparative neutralization 

tests; however, no virus has been detected. It has not been possible from the data 

available to determine whether these antibodies were produced after infection with a field 

strain of CSF virus or after vaccination with CSF vaccine. These findings increase the 

level of uncertainty regarding the presence or absence of CSF virus in Mexico. 

APHIS considers three possible explanations for the high serum neutralization (SN) titers 

found in the sera of pigs during several active and passive surveillance investigations: 

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exposure to CSF vaccine virus; exposure to field strain CSF virus; and false positive test 

results. 

APHIS concludes that for all of Mexico except Chiapas the most likely explanation for 

the serological findings is residual vaccine titers and/or continued illegal use of vaccine. 

However, the pattern of findings in Chiapas, along with its close proximity to known CSF 

viral activity in Guatemala, prevents APHIS from concluding that antibody detection in 

Chiapas is due solely to exposure to vaccine virus. 

Although APHIS is unable to recognize these States as free of CSF due to the uncertainty 

surrounding the serological findings, APHIS concludes that the risk of importing CSFinfected pork and pork products from the currently unrecognized States of Mexico, with 

the exception of Chiapas, is low and can be mitigated if certain requirements are met on 

the farms of origin and in the slaughterhouses and processing plants. These requirements 

are described below under Mitigations.

APHIS identified three risk factors associated with importing Mexican-origin pork and 

pork products into the United States from Mexico. 

Uncertainty regarding positive serological results

Serologic evidence of exposure in swine to CSF virus has been found in a number of 

Mexican States as recently as 2012. The specificity of the antibodies to CSF virus was 

demonstrated by comparative neutralization tests; however, no virus has been detected. It 

has not been possible from the data available to determine whether these antibodies were 

produced as a result of infection with a field strain of CSF virus or after vaccination with 

CSF vaccine. These findings increase the level of uncertainty regarding the presence or 

absence of CSF virus in Mexico. 

Incomplete epidemiological investigations of CSF suspect cases

During the last several years, the National Service of Agrifood Health, Safety and Quality

(SENASICA) has improved the quality and consistency of field epidemiological 

techniques and standards. However, these improvements have not been uniformly

implemented in all areas of the country. APHIS is concerned about continued problems 

with the quality of some epidemiological investigations of CSF suspect cases. 

Specifically, APHIS is concerned about the thoroughness of the investigations and lack 

of trace-in and trace-out activities of some suspect cases. In some investigations, staff 

have not selected appropriate animals to sample or have not chosen the most appropriate 

diagnostic test to run on the samples collected. For example, several cases involved

swine in which high titers to CSF antibodies had previously been detected; these were 

selected for sampling to test for CSF antigen and/or virus isolation long after live virus, if

it had been present, would likely have been cleared from the animal. In general, CSF 

antibodies are detectable 10 to 14 days post infection (dpi) at the earliest, while the ability 

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to isolate virus from tonsil tissue begins declining simultaneously with the appearance of 

antibody [3-8].1 

This problem could limit SENASICA’s ability to confirm or exclude CSF virus activity 

in accordance with international standards. However, APHIS acknowledges the ongoing 

efforts of SENASICA to address this issue, as evidenced by its recent attempts to correct 

investigation deficiencies. 

Proximity to CSF viral activity in neighboring countries

The existence of common land borders with CSF-affected regions in the south presents a 

risk for reintroducing CSF into Mexico. This factor is substantially mitigated because 

Mexico prohibits the importation of swine, pork, and pork products from countries it 

considers CSF-affected, including Belize and Guatemala. However, swine, pork, or pork 

products could be moved illegally into Mexico. The legal movement of people, vehicles,

or equipment that may be contaminated with undetected CSF virus may also reintroduce 

CSF into Mexico. 

Mitigations

Because of these risk factors, APHIS determined certain restrictions are necessary to 

mitigate the risk of release of CSF virus via fresh pork and pork products originating in 

and imported from a CSF-low-risk region in Mexico. The CSF-low-risk region in

Mexico recognized by APHIS includes all of Mexico except the 9-states currently 

recognized as CSF-free and the State of Chiapas for which APHIS considers the CSF risk 

to be unacceptable. These restrictions will require SENASICA to certify certain 

conditions on the farm of origin and at the slaughterhouse and processing plants. 

Therefore, APHIS proposes to: 

a) Allow importation of Mexican-origin pork and pork products from a CSF-lowrisk region in Mexico, subject to specified conditions.

1 The clinical signs and outcomes of CSFV infections vary considerably depending on the strain of virus as 

well as host and environmental factors. In general, antibodies are detectable 10 to 14 days post infection 

(dpi) at the earliest. In pigs with chronic CSF, neutralizing antibodies are detectable at the end of the first 

month post infection but disappear a few days afterwards [3- 6, 8]. 

Antigen detection is even more variable depending on the virus strain. For highly virulent CSFV strains 

(such as the Brescia strain), animals die within 9 to 14 dpi and virus is detected 2 to 4 dpi onwards. 

However, moderately virulent CSFV strains (like the Haiti strain) can be detected up to 28 dpi in tonsils 

using the PCR. Low virulent strains, like the Bavaro, have been detected in blood for up to 29 dpi, in tonsil 

scrapings for 21 dpi, and up to 70 dpi in histological sections of tonsil tissue [3, 6-8].

The times for virus detection in the same samples using the virus isolation (VI) test proved to be shorter. 

Some authors have explained this effect as the result of the formation of virus-antibody complexes. The VI 

test may start losing sensitivity simultaneously with the appearance of antibodies, around 14 dpi [6, 7].

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b) Restrict imports of pork and pork products originating in and imported from a

CSF-low-risk region in Mexico into the United States by requiring pork be

derived from swine raised on farms that operate under a high level of biosecurity

and where CSF antigen exposure has not been detected.

c) Require pork or pork products originating in and imported from a CSF-low-risk

region in Mexico be derived from swine not commingled with swine not

originating from herds operating under the required sanitary standards.

d) Require pork or pork products originating in and imported from a CSF-low-risk

region in Mexico not be commingled with pork or pork products derived from

swine not originating from herds not reared under the required level of sanitary

standards.

e) Apply restrictions described in 9 CFR 94.32 to pork and pork products originating

in and imported from a CSF-low-risk region in Mexico.

f) Require the establishment slaughtering swine intended for export to the U.S. to

allow periodic onsite evaluation and subsequent inspection of its facilities,

records, and operations by an APHIS representative.

APHIS proposes that SENASICA certify pork and pork products originating from a CSFlow-risk region in Mexico as derived from swine reared on premises meeting the 

following standards for sanitary conditions and biosecurity and not commingled with 

swine reared under less stringent standards: 

1. Herd is tested annually for CSF and the results show absence of antibodies to

CSF. The sampling protocol includes:

a. Serologic testing of the herd, using a testing protocol that allows

differentiation between CSF antibodies and cross-reactions with

antibodies to other pestiviruses. Sample size should be adequate to detect

5 percent prevalence at a 95 percent confidence level.

b. Samples from the herd may be collected at the slaughterhouse or the farm.

c. Any sick pigs showing clinical signs consistent with CSF are sampled and

tested for CSF antigen at any time. Any freshly dead or euthanized pigs

are necropsied and complete diagnostics for CSF performed.

2. Biosecurity measures include:

a. Containment of domestic pigs to prevent exposure to other swine, wildlife

or swine products.

b. Cleaning, disinfection, and control of movement of vehicles entering

farms or transporting swine.

c. Control of personnel entering the farm and keeping a written visitors’ log.

d. Training of personnel and farm veterinarians in awareness of risk of

fomite spread and clinical signs of CSF.

e. Recordkeeping of animal movements into and out of the farm (including

species other than swine).

f. Prohibition of swill feeding on the farm.

g. Documentation of adequate pest control on the farm.

h. Prohibition of farm personnel from owning or working with other swine or

in swine slaughter facilities.

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3. Replacement stock and swine semen are sourced only from herds of equivalent

sanitary status not located in regions considered by APHIS to be CSF-affected or

are replacement stock or semen-donor boars that have tested negative for CSF

while being quarantined before introduction to the destination farm or semen

collection center.

4. Herds are not epidemiologically linked to CSF outbreaks and have not been

located within protection and surveillance zones established in response to CSF

outbreaks within the previous 12 months.

5. Herds are inspected annually by SENASICA, which verifies compliance with the

above conditions.

APHIS will also propose special restrictions requiring pork or pork products originating

in and imported from a CSF-low-risk region in Mexico to be derived from swine not 

commingled with swine originating from herds not meeting these sanitary standards. The 

proposed rule will also require pork or pork products originating from a CSF-low-risk 

region in Mexico for export to the United States to not commingle with pork or pork 

products derived from swine originating from herds not meeting the sanitary standards

described above. 

APHIS also intends to impose special restrictions described in 9 CFR 94.32. APHIS 

considers Mexico to meet the criteria described in this regulation because Mexico shares

a common land border with countries APHIS does not recognize as CSF-free. These 

restrictions prohibit the importation of pork and pork products derived from swine 

originating in or ever living in regions APHIS considers CSF-affected. Pork or pork 

products must derive from swine slaughtered at a federally inspected establishment in a

region of Mexico from which pork or pork products are eligible for export to the United 

States. Further, the regulation prohibits the importation of pork or pork products that 

might have commingled with or be contaminated by pork or pork products derived from 

swine originating in CSF-affected regions.

APHIS concludes these mitigations will greatly reduce the likelihood that pork and pork 

products originating in and imported from a CSF-low-risk region in Mexico might be 

infected with or contaminated by CSF virus. 

Exposure Assessment

APHIS assessed the likelihood of exposure of susceptible swine populations in the United 

States to CSF virus in fresh pork or pork products originating in and imported from a 

CSF-low-risk region in Mexico. Studies of the U.S. waste-feeding sector led APHIS to 

conclude susceptible swine in the United States are unlikely to be exposed to the CSF 

virus via waste feeding. 

Consequence Assessment

The biological and economic consequences of introducing CSF virus into the United 

States could be substantial, although they would likely vary based on the extent of the 

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outbreak at the time of detection, the virus serotype introduced, and movement and 

demographics of affected swine. Additionally, restrictions imposed by international 

trading partners could cause severe economic losses to the U.S. livestock industry.

Risk Estimation

In summary, although the consequences of a CSF outbreak in the United States would be 

serious, based on the findings of the release and exposure assessments APHIS believes 

our proposed mitigations will significantly lower the risk of CSF-infected pork or pork 

products entering the United States from a CSF-low-risk region in Mexico and exposing 

U.S. swine to the disease.

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Section 2. Introduction

History

APHIS currently allows the importation of fresh pork and pork products from nine 

Mexican States it had previously evaluated and recognized as free of CSF [9-11]. Those 

States are Baja California, Baja California Sur, Campeche, Chihuahua, Nayarit, Quintana 

Roo, Sinaloa, Sonora, and Yucatan. Recognition of those nine states was based on 

conditions that existed at the time they were initially evaluated, including restrictions on 

the movement of live swine, pork and pork products that mitigated the risk of 

reintroducing CSF virus into those States. At that time, Mexico regionalized its territory 

while conducting the National CSF Campaign to eradicate the disease. In January 2009, 

Mexico declared that CSF had been eradicated and removed all remaining movement 

controls upon which its regionalization of the country had been based. 

In November 2007, the Government of Mexico submitted a request to the Animal and 

Plant Health Inspection Service (APHIS) seeking recognition of the classical swine fever 

(CSF) status of the States of Aguascalientes, Colima, Guanajuato, Jalisco, Michoacán, 

Querétaro, San Luis Potosí, and Zacatecas to allow the export of fresh pork and pork 

products originating in these States to the United States. Collectively, these States are

known as the Central Western Region (CWR) [1]. Mexico had declared these States free 

of CSF in July 2006 after conducting a CSF eradication campaign. On receiving this 

request, APHIS initiated an evaluation of the CSF status of the CWR (see Figure 1). In 

September 2008, the Government of Mexico expanded their request to include evaluation 

of the State of Puebla which had been declared CSF-free in December 2006. In 2009, 

Mexico expanded its request to include all Mexican territory after its January 30, 2009 

declaration that the entire country was CSF-free. 

APHIS technical teams made two site visits to the CWR, the first in May 2008 and the 

second in April 2012. In December 2012, APHIS conducted a site visit to evaluate the 

remaining unrecognized States of Mexico. The results of these evaluations provided the 

basis for APHIS to decide whether and under what conditions to allow the importation of 

fresh pork and pork products originating from additional regions in Mexico.

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Figure 1 – Map of Mexico

Source: USDA:APHIS:VS:CEAH

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APHIS 2008 Site Visit to CWR

During the two years prior to the site visit, the National Service of Health, Food Safety 

and Agro-Alimentary Quality (SENASICA) posted the results of Mexico’s national CSF 

surveillance program on its website. These results included numerous epidemiological 

alerts which were listed whenever positive serological samples were detected. 

SENASICA was unable to confirm CSF cases related to any of these alerts. APHIS was 

concerned that the number of positive samples reported for the CWR exceeded the 

number of false positives that might reasonably be expected from active surveillance in a 

region free of CSF.

An APHIS technical team visited the CWR in May 2008 to evaluate the status of the 

region and to assess the situation. The team sought to verify how Mexico excluded 

circulating CSF virus as the underlying cause for the positive surveillance test results.

Although the team observed many strong points in Mexico’s veterinary infrastructure, 

movement controls, and commercial farm biosecurity, APHIS identified critical 

deficiencies in the CSF surveillance systems, epidemiological follow-up, and laboratory 

capacities which introduced uncertainty in the assessment of SENASICA’s ability to 

reasonably determine the presence of circulating CSF virus in the CWR. APHIS 

concluded that the ability to detect CSF virus was necessary to confidently support a 

declaration of CSF-freedom and to quickly detect CSF virus if it were reintroduced into a 

disease-free area.

As a result of these observations, APHIS did not proceed with regulatory action to 

recognize the CSF status of the CWR. Under existing APHIS regulations, pork and pork 

products from the region were eligible for importation only under the conditions 

described in 9 CFR 94.9 (processed in a way to inactivate the CSF virus). Importation of 

live swine, swine semen, and fresh pork from this region of Mexico continued to be 

prohibited due to the risk of CSF.

APHIS Technical Assistance

During 2011 at the request of SENASICA, APHIS provided technical assistance 

regarding CSF laboratory diagnostic protocols and techniques, field investigation 

methodology and surveillance strategy. As a result of this joint effort, Mexico developed 

a national standard protocol for appropriate laboratory procedures and epidemiologic 

follow-up to positive serological findings utilizing a standardized diagnostic protocol.

In the fall of 2011, personnel from APHIS’ Foreign Animal Disease Diagnostic 

Laboratory (FADDL) at Plum Island extensively reviewed SENASICA’s laboratory 

network and their findings (from training, site visits, document reviews, and proficiency 

panel testing) were favorable. FADDL reviewed the BSL3 laboratory at Palo Alto and 

verified their competency to conduct CSF confirmatory testing with an effective date of 

Sept. 13, 2011 (see Appendix 1). APHIS considers confirmatory tests conducted after 

that date to be valid. 

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In November 2011, APHIS foreign animal disease diagnosticians accompanied 

SENASICA personnel on investigations of suspect cases (i.e. positive results on CSF 

screening tests) in Jalisco. APHIS personnel considered Mexico’s field investigation 

methodology for these suspect cases in Jalisco to be acceptable, although deficiencies 

were observed in other case investigations described subsequently in this document. 

However, the presence of CSF virus could not be excluded or confirmed. The CSF 

antibody detection in those and other suspect cases remains unexplained; however, the 

absence of clinical disease or expansion of CSF antibody detection suggests that either 

CSF virus had not been present or had been effectively eliminated. FADDL conducted 

further testing on samples received from SENASICA in an attempt to develop a 

technique to exclude or confirm CSF in these cases.

APHIS 2012 Site Visits

In April 2012, APHIS made a site visit to the CWR. This region includes one of the 

major pork production areas of Mexico. In December 2012, APHIS conducted a site visit 

to evaluate all remaining unrecognized Mexican States. The observations and information 

obtained during these visits are described in the following release assessment.

Documentation

Supporting documentation reviewed for this risk assessment came from the Secretaria de 

Agricultura, Ganaderia, Desarrollo Rural, Pesca y Alimentacion (Secretariat of 

Agriculture, Livestock, Rural Development, Fisheries and Food, or SAGARPA) and 

Mexican State governments; observations made by APHIS technical teams during site 

visits in May 2008, April 2012 and December 2012; peer-reviewed articles; and data 

from the World Organization for Animal Health (OIE) and other technical sources.

Methodology

This risk analysis was conducted according to the format recommended by OIE and, 

therefore, includes a hazard identification section, a release assessment, an exposure 

assessment, a consequence assessment, and a risk estimate [2]. The hazard under 

consideration is CSF virus. The risk assessment allowed APHIS to decide whether and 

under what conditions to accept the importation of fresh pork and pork products from 

additional Mexican States.

Application

APHIS previously recognized Mexico as a region in which other swine diseases, 

specifically swine vesicular disease (SVD) and foot-and-mouth disease (FMD), were not 

known to exist [12]. In addition, APHIS does not consider Mexico to be affected with 

African swine fever. CSF is the hazard being evaluated in this analysis. 

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Section 3. Hazard Identification

The World Organization for Animal Health (OIE) lists several animal diseases that are 

considered primary hazards associated with trade of animals and animal products. APHIS 

regulations mitigate the risk of introduction of these foreign animal diseases in to the 

United States. As such, APHIS conducts an import risk analysis addressing hazards of 

primary concern prior to initiating or resuming trade of animal commodities. APHIS 

considers classical swine fever (CSF) virus to be a potential hazard associated with trade 

of live swine and swine products. CSF was eradicated from the United States in 1976.

Causative agent 

Classical swine fever, also known as hog cholera, is a highly contagious disease of swine 

caused by a Pestivirus of the family Flaviviridae [13]. Only one serotype has been found. 

Host range 

Natural hosts of CSF virus are members of the Suidae family, including domestic and 

wild swine [14]. Infected swine are the only reservoir of virus [15]. The role of wild boar 

as a virus reservoir and source of infection for domestic swine is well known and 

epidemiological links between CSF infection in wild boar and domestic swine have been 

reported repeatedly in recent years 16, 17].

Incubation period 

The incubation period for CSF is 2-14 days [15, 18]. 

Morbidity and mortality 

Four distinct clinical forms of CSF have been described: acute, chronic, congenital, and 

mild [19, 21]. The acute form is characterized by high fever, anorexia, lethargy, and 

hemorrhagic lesions and cyanosis of the skin. Death occurs 5-25 days after onset of the 

illness; mortality in young pigs can approach 100 percent. The chronic form, seen 

primarily with less virulent CSF virus strains or in partially immune herds, presents as 

fever, dullness, growth retardation, and diarrhea for up to 1 month. Pigs often appear to 

recover only to relapse and die within about 3 months. Depending on the virulence of the 

virus strain and the stage of gestation, the congenital form can present at fetal death, 

resorption, mummification, or abortion. If born alive, the piglet may exhibit congenital 

tremor, weakness, and/or poor growth leading to death. Conversely, piglets may be born 

clinically normal but persistently viremic with intermittent virus shedding (no antibody 

response). The mild form, which usually occurs in older animals, is characterized by 

transient fever and loss of appetite with recovery. Infected sows may show no overt 

clinical signs but continuously shed virus to their young and to other swine they contact. 

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Sources of virus and transmission 

Blood and all tissues, secretions, and excretions of sick and dead animals are sources of 

virus [18]. CSF virus has been recovered from muscle and lymph nodes of infected pigs, 

and high titers of CSF virus have been isolated from bone marrow [22]. The virus may 

also be present in semen [19].

Transmission is generally directly from pig to pig, but products including fresh, frozen, or 

cured pork can infect other pigs via the oral route [23]. Imported pig products are 

frequently implicated in the introduction of CSF virus into previously free regions, 

primarily through the practice of swill feeding [24]. Dahle and Liess (1992) demonstrated 

that the oral infectious dose of CSF virus is very low [25]. Indirect transmission may 

occur via movement of people, wild animals, and inanimate objects such as live-haul 

trucks [26].

In countries that are free of CSF in domestic swine, epidemics in wild boar are often 

started by feeding of infected human food waste. Abnormal mortality and sometimes 

obviously sick animals are the first indicators of CSF introduction into a wild boar 

population [27].

Inactivation and survival

The CSF virus is quite hardy, being stable between pH 4 and 10 [28] and also stable at 

low temperatures [29]. The virus can survive for long periods in cool, moist, and proteinrich environments such as stored meat: survival times of more than 4 years in frozen 

pork and at least 85 days in fresh, chilled pork have been reported [23]. CSF virus would 

likely remain viable in fresh meat even after carcass maturation and is unlikely to be 

destroyed by transport or cold storage. Survival times in cured or smoked meat ranging 

from 17 days to more than a year have been reported. 

The CSF virus is readily inactivated by detergents, lipid solvents, proteases, and common 

disinfectants, as well as pasteurization and cooking, although sensitivity to heat can vary 

among strains. The virus can be inactivated by a variety of time/temperatures 

combinations as well as curing and drying through various processes [30]. CSF virus is 

moderately fragile in the environment, but can remain infectious for months in 

refrigerated meat and years in frozen meat [15]. 

Vaccination 

Vaccines against CSF virus are available in some areas. Vaccination can protect animals 

from clinical disease but does not prevent infection. Currently available live attenuated 

vaccines are effective in limiting clinical disease but allow the CSF virus to circulate 

subclinically. Vaccination is therefore considered inappropriate in regions where a 

stamping out policy exists and where the entire swine population is susceptible due to the 

standard practice of non-vaccination [31]. In areas where CSF is endemic, well16
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administered vaccination programs can eventually eliminate the infection from herds 

[15].

Laboratory Diagnosis 

Laboratory confirmation of infection, essential during an outbreak situation, is 

complicated by the close antigenic relationship of the CSF virus with bovine viral 

diarrhea virus and border disease virus (also pestiviruses) [13]. Identification of the virus, 

its nucleic acid, or associated antibodies confirms the diagnosis. The OIE recommends 

detection of CSF antigen via direct fluorescent antibody test on cryostat sections of 

organs from infected pigs [32]. A panel of monoclonal antibodies is then used to 

differentiate from other Pestivirus antigens. Virus isolation techniques and polymerase 

chain reaction may also be used. Antigen-capture enzyme-linked immunosorbent assays 

(ELISAs) are useful for herd screening, but should not be used on a single animal basis.

Detection of virus-specific antibodies is particularly useful in herds suspected of being 

infected at least 21 days previously with CSF virus [32]. Serological methods are 

essential if a country wishes to be internationally recognized as being free from the 

disease in the absence of vaccination. Screening tests must be followed by confirmatory 

tests that are specific to the CSF virus. Certain ELISAs are relatively CSF specific, but 

the definitive method for differentiation is the comparative neutralization test, which 

compares the level of antibodies to different Pestivirus species.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Section 4. Release Assessment

A release assessment describes the biological pathway(s) necessary for an importation 

activity to introduce pathogenic agents into a particular environment and estimates the 

probability of that introduction [2]. This release assessment addresses the factors 

described under 9 CFR 92.2 for evaluation of the animal health status of a region [33].

Risk factors and issues of concern, which may directly or indirectly affect the risk 

estimate, are identified during this process. APHIS evaluated the current status of 

Mexico with regard to CSF to decide whether it can allow the importation of fresh pork 

and pork products originating from additional Mexican States and under what conditions.

 

4.1. Scope of the evaluation 

 

APHIS considers all of the territory of Mexico, except the nine states that APHIS 

currently considers as CSF-free, in this evaluation of the classical swine fever (CSF) risk 

for importation of pork and pork products originating in and exported from this region of 

Mexico (see Figure 1, page 11). 

 

 4.2. Veterinary control and oversight 

Organization of the Official Veterinary Services [36-60]

Central veterinary authority

The Secretaria de Agricultura, Ganaderia, Desarrollo Rural, Pesca y Alimentación

(SAGARPA, Ministry of Agriculture, Livestock Production, Rural Development, 

Fishery, and Food) is the Federal department within the government of Mexico

responsible for the agriculture and livestock sectors. SAGARPA is considered equivalent 

to United States Department of Agriculture (USDA). 

Within SAGARPA, there is Servicio Nacional de Sanidad, Inocuidad y Calidad 

Agroalimentaria (SENASICA, the National Service of Agrifood Health, Safety and 

Quality). SENASICA, equivalent of USDA’s Animal and Plant Health Inspection 

Service (APHIS), is divided into several general divisions; three of them are directly 

focused on animal health issues (see Appendix 2: SENASICA Organization Chart). 

These divisions are Direccion General de Salud Animal (DGSA, General Directorate of 

Animal Health); Direccion General de Inspeccion Fitozoosanitaria (DGIF, Animal and 

Plant Health Inspection Service General Direction); and Direccion General de Inocuidad 

y Calidad Agroalimentaria (DGICA, General Directorate of Agrifood Safety and Quality 

Control). The role of these divisions in CSF control in Mexico is discussed below.

The DGSA, headed by the Chief Veterinary Officer of Mexico, is comprised of four

animal health divisions and is supported by three additional entities. 

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Evaluation of the CSF Status of a Region in Mexico October 2013

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The Dirección de Importación, Exportación, Servicios y Certificación Pecuaria

(Directorate of Import, Export, Services, Animal and Animal Products Certification) is 

responsible for issuing import and export permits for animals and animal products;

registration and regulation of the manufacture of veterinary products (chemical, 

pharmaceutical, biological and feed products); approval of animal disease diagnostic and 

product quality control laboratories; accreditation of veterinarians in certain disciplines 

(laboratory diagnostics, ruminants, poultry, swine, animal and animal product movement, 

slaughterhouses, and the manufacture of pharmaceutical, biological, and/or food 

products); and issuing health certificates necessary for movement of animals and/or 

animal products within Mexico.

The Dirección de Campañas Zoosanitarias (Directorate of Animal Health Programs) is 

responsible for animal health programs conducted in Mexico to control and eradicate 

animal diseases. This division was responsible for conducting Mexico’s National 

Classical Swine Fever Campaign which is described later in this document.

The Dirección de Vigilancia Epidemiológica (Directorate of Epidemiological 

Surveillance) is responsible for analyzing surveillance data and developing risk analyses 

in support of domestic and foreign regionalization decisions.

The Dirección de Sanidad Acuícola y Pesquera (Directorate of Animal Health 

Aquaculture and Fisheries) is responsible for aquaculture and fisheries health programs 

conducted in Mexico to control and eradicate diseases and plagues affecting live aquatic 

species. This Direction was incorporated to the structure of the Animal Health Direction 

in 2007.

The animal health activities of DGSA are supported by the Comision Mexico-Estados 

Unidos para la prevencion y control de la fiebre aftosa y otras enfermedades exoticas

(CPA, Mexico-United States Commission for the Prevention of Foot and Mouth Disease 

and other Animal Foreign Diseases), located in Mexico City. CPA is in charge of the 

prevention, surveillance, diagnosis, control and eradication of exotic and emerging

animal diseases and pests. Its structure is within SENASICA and is part of DGSA. CPA

operates a foreign animal disease diagnostic laboratory network. 

Since the January 2009 self-declaration by the Government of Mexico that its entire 

territory is free of CSF, the CPA laboratory has assumed the responsibility for all CSF

diagnostic testing. The national territory has been divided into eight regions, commanded 

by 8 Regional Coordinators and 69 Zone Coordinators that respond to the notifications of 

suspicious exotic and emerging animal disease and pest cases. CPA is also involved with 

a continuous training program, performed through courses, seminars and drills, aimed to 

SAGARPA personnel and personnel from State Committees for Animal Production 

Promotion/Protection, and other professionals from different institutions, such as the 

Secretary of Environment and Natural Resources, Secretary of National Defense, or the 

Secretary of Public Education. This allows the personnel specialization and selection for, 

afterwards, being part of the respective organization chart of the State Groups for Animal 

Health Emergency or GEESA by its Spanish abbreviation in initials.

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Centro Nacional de Servicios de Diagnostico en Salud Animal (CENASA), Mexico’s 

national veterinary services diagnostic laboratory, is centrally located in Tecamac, State 

of Mexico. This laboratory receives submissions for the diagnosis of endemic animal 

diseases; verifies the quality control of biological products submitted to SAGARPA for 

their official registration; and accredits other laboratories in Mexico for animal disease 

proficiency and quality control. 

A second national laboratory, Centro Nacional de Servicios de Constatacion en Salud 

Animal (CENAPA), located in Jiutepec, State of Morelos, is the toxicology laboratory 

responsible for toxic and pesticide residue analyses of food of animal origin. This 

laboratory also verifies the quality control of tick pesticides submitted to SAGARPA for 

their official registration.

DGIF, the second of three SENASICA divisions involved in animal health activities, is 

responsible for the Sistema Nacional de Cuarentena Agropecuaria (National System of 

Animal and Agricultural Quarantine), a system of Federal inspection check points 

providing internal and external movement controls for animal and animal products. The 

External Quarantine Service provides sanitary control activities at ports, airports and 

borders to prevent introduction of animal diseases into Mexico via animal and animal 

product importation. The Internal Quarantine Service manages all activities relevant to 

preventing the spread of diseases already existing within the entire national territory, 

from affected areas into free areas. There are 45 permanent federally maintained 

inspection posts on major highways distributed along five corridors in Mexico, the 

northern, central, southern, isthmus and peninsular quarantine lines. These effectively 

divide Mexico into six regions. The federal inspections posts provide general animal 

health movement controls, including swine movement controls for pseudorabies. After

Mexico’s self-declaration of CSF-freedom in January 2009, there are no specific CSF 

movement restrictions. In addition to Federal inspection posts, there are State-operated 

inspection posts throughout the country which perform varying animal-health-related 

duties. The role of the inspection posts are described later in this document.

DGICA, the third division of SENASICA with animal health responsibilities, has 

authority over federally approved slaughterhouses and meat processing and handling 

facilities, known as Federal Inspection Type Establishments (TIF).2 DGICA is 

equivalent to USDA’s Food Safety and Inspection Service (FSIS). To ensure 

compliance, TIF establishments have permanent (i.e. stationary) Federal personnel with 

oversight over the animal health processes and products. These establishments comply

with international sanitary requirements, have official veterinary officers and are certified 

by the countries to which they export. TIF supervisors, assigned to an area or State, 

2 Federal Inspection Type Establishments (TIF) are slaughterhouses and meat processing and handling 

facilities approved by DGICA, an agency equivalent to USDA, Food Safety and Inspection Service (FSIS). 

TIF establishments have permanent sanitary inspection of their processes and products through official 

veterinarians to monitor compliance with SAGARPA regulations. These establishments comply with 

international sanitary requirements and have official veterinary officers and are certified by countries to 

which they export. Pork or pork products must be processed through FSIS-approved TIF establishments 

for export from Mexico to the United States.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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verify the activities of the official veterinarians in charge at the TIF establishments. In 

addition, throughout the country there are State-inspected municipal plants slaughtering 

swine and processing pork for local markets and personal consumption under the 

supervision and control of the Department of Health. 

In each State there is a Federal SAGARPA delegate in charge of all Federal personnel 

responsible for animal health activities. Among other duties, these official veterinarians 

are responsible for ensuring compliance with Mexican Official Standards (NOMs) 

regarding animal health control and surveillance programs, including local prevention 

and control measures, reporting livestock census information, emergency response, 

sampling, premises identification, movement controls and record-keeping.

State veterinary authority [36-60]

The animal health infrastructure at the State level exists as collaboration between the 

SAGARPA Delegation in the State (SAGARPA State Delegation), the State Government, 

and a State animal health committee comprised of industry and producer representatives, 

Comitéde Fomento y Proteccion Pecuaria, or CEFPP [see Figure 2]. In addition there 

are various organizations and associations representing the interests of livestock 

producers. In total, there are 33 State CEFPPs in the country, where 1,415 veterinarians 

work.

Figure 2.

Source: SAGARPA [36-60]

In Mexico, much of the field work for SAGARPA’s animal health activities is provided 

through the State CFPP which receives funding from the State government, the livestock 

STRUCTURE OF STATE VETERINARIAN SERVICES 

STATE BRANCH 

OFFICES IN 

SAGARPA

SECRETARIES OF 

AGRICULTURE AND 

ANIMAL PRODUCTION 

DEVELOPMENT

STATE COMMITTEE OF 

ANIMAL PRODUCTION 

DEVELOPMENT AND 

PROTECTION

HEAD OF THE 

PROGRAM OF ANIMAL 

HEALTH AND 

SUPPORTING STAFF

HEAD OF 

CADER

HEAD OF 

DDR

SUPPORTING 

STAFF

S.C. 

BOVINES

S.C. 

BIRDS

S.C. 

PIGS

S.C. 

BEES

S.C. 

MOV.

S.C. 

EPIDEM.

21
Evaluation of the CSF Status of a Region in Mexico October 2013

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industries in the State, and the SAGARPA State Delegation. Each of these parties 

contributes a third of the budget required for supporting the yearly sanitary activities. 

The annual budget and program of activities of the CFPP is approved by SAGARPA. 

As part of the National CSF Emergency Plan which is discussed later in this document, 

are the Grupos Estatales de Emergencia en Salud Animal (State Animal Health 

Emergency Groups, GEESAs). GEESAs are composed of animal health personnel from 

the Federal and State governments, CFPP, industry, swine producers, and private 

veterinarians. These individuals receive training in foreign animal diseases and 

participate in simulation exercises and respond to emergency situations at the State and/or 

Federal level. 

Legal Authority for Animal Health Activities [34-60]

The Federal Law of Animal Health is the legal basis applied in all the Mexican Republic 

and is the equivalent of USDA, APHIS’ Animal Health Act. Article IV of this Law, 

gives SAGARPA the authority to promote, encourage, organize, supervise, coordinate 

and execute, all types of activities pertaining to animal health in which different 

organizations and agencies of the municipal, State and Federal governments can 

participate as well as individual stakeholders.

The Mexican Official Standards or NOMs (Normas Oficiales) are the Federal laws 

regulating these activities. From 1995 until January 2009, Mexico conducted a CSF 

eradication campaign under regulations authorized by NOM-037-ZOO-1995 and is 

described later in this document. 

Although NOM-037-ZOO-1995 remains in effect after Mexico declared their entire 

territory to be CSF-free, the NOM provides continued authority to conduct CSF 

surveillance activity, prohibition of CSF vaccination and emergency response for in cases 

of CSF suspicion [34]. Eventually Mexico will replace this NOM with a different type of 

regulatory instrument. According to SENASICA, the new regulatory instrument will be 

called the “Agreement in which are disclosed the animal health measures applicable for 

classical swine fever for the epidemiological surveillance in the Mexican United States 

Territory.” This Agreement will provide the authority to establish the epidemiological 

surveillance and investigation activities to monitor for any reintroduction of CSF into 

Mexico, including the regulation of trade, and the emergency response authority if 

reintroduction occurs. The Agreement will also provide case definition and diagnostic 

parameters for CSF, prohibit the use of CSF vaccine in the country (except if an animal 

health emergency is declared), and describe the process by which Mexico will recognize 

the CSF status of exporting countries.

Other NOMs which impact the control of CSF in Mexico are:

• NOM-046-ZOO-1996, National Epidemiological Surveillance System.

• NOM-018-ZOO-1995, Verification by Approved Veterinarians.

• NOM-003-ZOO-1994, Animal Disease Diagnostic Laboratory Criteria.

• NOM-036-ZOO-1996, Minimum Requirements for CSF Vaccines.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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• NOM-054-ZOO-1996, Quarantine Procedures for Animal and Animal Products.

Discussion

APHIS concludes that Mexico has the necessary veterinary infrastructure to conduct CSF 

control activities. One of the strengths observed by the APHIS site-visit team was the 

apparent cooperation existing within the different components of the State veterinary 

infrastructure, including the State SAGARPA Delegation, State Government, State 

Animal Health Committee and producer and industry organizations. However as an 

exception to this strength, the APHIS team observed weaknesses in the communication 

and cooperation between States and between State and Federal entities in regards to 

epidemiological investigations that involved more than one State. During the period of 

the APHIS evaluation, Mexico has improved inter-agency communication; however, as 

discussed later in this document, APHIS recommends continued improvement to involve 

the laboratory diagnosticians in communications regarding epidemiological 

investigations (see section 4.9. Disease surveillance in the region). 

 

4.3. Disease history and vaccination practices [36-60]

Disease status in the region

In January 2009, the Government of Mexico declared that the entire country was free of 

CSF in accordance with the National CSF Campaign, as described in the Official 

Mexican Standard NOM-037-ZOO-1995 which is discussed later in this document [34]. 

This declaration was the culmination of the National Campaign which officially began in 

Mexico in 1980. The last CSF outbreak in domestic swine in Mexico reported to the OIE 

occurred in Guerrero in 2009 [41, 42, 65].

3

 The last reported cases in each State under 

review are summarized in Table 1. 

3 In December 2009, SENASICA reported to the OIE the occurrence of 2 CSF outbreaks in the State of 

Guerrero during March 2009 [41, 65]. The source of the outbreaks was not determined. This report 

remains the official statement to OIE by SENASICA regarding these outbreaks and the OIE continues to 

recognize that the last CSF outbreak in Mexico occurred in 2009. However during the November 2012 site 

visit, SENASICA advised the APHIS team of a contradictory conclusion reached during a retrospective 

study recently conducted by SENASICA. SENASICA presented documentation to APHIS asserting that 

the 2009 diagnostic tests confirming CSF virus were invalid; however, the information provided to APHIS 

was inconclusive and therefore insufficient for APHIS to discount the 2009 OIE report [41, 42, 65]. 

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Table 1: Significant Dates for the CSF Campaign in Mexico 

State

Last 

Outbreak

Year

Last 

Vaccination 

Year

Eradication

Phase

Year

Date

Free phase

Declared

Aguascalientes 1999 2002 2004 July 18, 2006

Chiapas 2002 2006 2006 January 30, 2009

Coahuila 1984 1993 1993 July 24, 1995

Colima 1999 2004 2004 July 18, 2006

District Federal 1999 2006 2006 June 9, 2008

Durango 1998 1994 1994 October 7, 1999

Guanajuato 2003 2004 2004 July 18, 2006

Guerrero 2009 2005 2005 August 1, 2007

Hidalgo 2003 2005 2005 March 12, 2007

Jalisco 2001 2004 2004 July 18, 2006

Mexico 2005 2006 2006 June 9, 2008

Michoacán 1999 2004 2004 July 18, 2006

Morelos 1998 2006 2006 June 9, 2008

Nuevo Leon 1990 1993 1993 July 24, 1995

Oaxaca 1998 2005 2005 January 30, 2009

Puebla 1998 2005 2005 December 6, 2006

Querétaro 2000 2000 2004 July 18, 2006

San Luis Potosí 1999 1998 2003 July 18, 2006

Tabasco 2000 2005 2005 January 30, 2009

Tamaulipas 1999 1993 1993 July 24, 1995

Tlaxcala 2005 2004 2005 March 12, 2007

Veracruz 1998 2005 2005 December 6, 2006

Zacatecas 1991 2004 2004 July 18, 2006

Source: SAGARPA [39, 41]

Mexican officials claim that feral swine or free-roaming wild pig populations are not 

known to exist in Mexico. However, there are several commercial farms raising herds of 

wild collared peccaries and European wild boars for sporting purposes. These farms are 

located in areas distant from domestic commercial swine production facilities. These 

herds are also monitored as part of the national CSF surveillance activities. Exposure to 

CSF virus has not been detected in these herds. APHIS does not consider it likely that 

feral swine or wild boar are a risk for introduction or spread of CSF virus in Mexico.

As previously mentioned in the introduction (see Section 2), SENASICA had reported a 

pattern of serological detection of antibodies to CSF prior to the 2008 site visit by 

APHIS. During that site visit APHIS identified deficiencies in the laboratory diagnostic 

protocols and epidemiological investigation of suspect cases that cast doubt on 

interpretation of the laboratory results and investigation reports. APHIS provided 

technical assistance to and worked with SENASICA to resolve these problems and 

subsequently in September 2011determined that Mexico’s foreign animal disease 

laboratory network (discussed in more detail later in this document) were operating in 

accordance with international standards. 

However, SENASICA continued to report serological findings of CSF antibody 

detection, collected during both active and passive surveillance activity, although at less 

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Evaluation of the CSF Status of a Region in Mexico October 2013

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frequency than in 2008. APHIS audited the epidemiological and laboratory records for 

these suspect cases for each state under evaluation. Most states had several suspect cases 

that occurred after September 2011. In addition, APHIS sent a team of foreign animal 

disease diagnosticians (FADDs) to assist with the collection of samples for suspect case 

investigations in the State of Guanajuato (see Appendix 4). In cases where clinical signs 

of disease were present, the investigations often revealed one or more diseases that may 

have been either co-existing with or unrelated to infection with CSF virus. CSF virus 

could not be confirmed in any of these suspect case investigations; however, the cause(s) 

of the CSF antibody detection remained unexplained.

During the two 2012 site visits, the APHIS team again audited suspect case investigations

and laboratory records. In most cases, the records indicated that the investigators 

followed proper procedures to close the investigations by excluding CSF as the most 

likely cause of antibody detection. However, in 10 States (Chiapas, Colima, Guanajuato, 

Guerrero, Hidalgo, Jalisco, Mexico, Michoacán, Morelos and Tabasco) there was at least 

one suspect case for each state in which CSF virus exposure could not be ruled out

because the investigations were incomplete. In many of these cases, investigators either 

did not sample the appropriate animals with the appropriate diagnostic test or the animals 

were improperly identified or destroyed before the proper sampling and testing could be 

conducted. In other case investigations, APHIS is concerned about the thoroughness or 

lack of trace-in and trace-out activities. SENASICA with technical assistance from 

APHIS has made significant improvement in implementing field investigation protocols 

that meet internationally recognized standards. However, additional work needs to be 

done to raise the level of performance in all states, especially Chiapas.

It is important to note that CSF virus was never confirmed or isolated in any of these 

suspect cases and in most of these cases clinical signs of disease were absent. It is also 

important to note that sero-conversion within the herd and surrounding herds was not 

observed. In a few instances where clinical signs of disease were present, the 

investigators were able to confirm other infections but such findings neither increase nor 

decrease suspicion of CSF exposure as a co-existing factor. 

In the case of Chiapas, the APHIS team noted that a cluster of 7 suspect cases were 

detected in 2012 near the border with Guatemala which at the time was experiencing a 

CSF epidemic. This cluster was characterized by extremely high serum neutralization 

titers (in excess of 1:2,560) specific to CSF virus, ruling out exposure to other 

pestiviruses. The case investigations could not determine the cause of these high titers 

but CSF virus was never confirmed or isolated.

Discussion

Serologic evidence of exposure to CSF virus has been found in a number of Mexican 

States. The specificity of the antibodies was demonstrated by comparative neutralization 

tests; however, no virus has been detected. It has not been possible from the data 

available to determine whether these antibodies were produced after infection with a field 

strain of CSF virus or after vaccination with CSF vaccine. At this time there is no 

25
Evaluation of the CSF Status of a Region in Mexico October 2013

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diagnostic test that can distinguish between exposures to the field virus versus exposures

to the PAV-250 CSF vaccine last used in Mexico and currently in use in Central 

America. These findings increase the level of uncertainty regarding the presence or 

absence of CSF virus in Mexico. 

APHIS considers three possible explanations for the high SN titers found in the sera of 

pigs during several active and passive surveillance investigations. From most likely to 

least likely, these three explanations are:

1) Exposure to CSF vaccine virus: possible explanations include illegal use of 

vaccine (smuggled into Mexico or diverted from vaccine produced in Mexico for 

export) or residual titers from legal vaccination prior to 2006 (smuggled 

vaccinated pigs is a possibility however not likely due to the strength of border 

inspection activities). However it is important to note that legal vaccination 

ceased more than 6 years ago in Mexico and most seropositive swine found in 

Mexico were animals from 3 to 5 years of age although some were less than two.

2) Exposure to field strain CSF virus: high SN titers in several pigs in multiple 

states and clustering of cases near the border with Guatemala support this 

explanation. However, in all suspect case investigations that APHIS reviewed and 

consider to be complete, antigen tests have not revealed live CSF virus and tests 

from perifocal sampling have not documented spread of infective CSF virus. 

3) False positive test results: no diagnostic test has perfect specificity, although this 

explanation is thought to be least likely because of the combined specificity of the 

series of CSF serological tests (ELISA, immunoperoxidase (IP) and serum 

neutralization (SN)) approaches 100%. Both reference and regional laboratories 

exhibited excellent performance on CSF diagnostic tests, record keeping, and 

quality assurance.

Since the pattern of CSF antibody detection in several areas of Mexico is unexplained

from the evidence presented, then the level of uncertainty, regarding the presence or 

absence of CSF virus in the country, is increased. It is possible that such a pattern could 

be indicative of a country in the last stages of eradication of CSF, perhaps a country that 

has recently eradicated CSF but has residual CSF antibodies and/or sporadic illegal CSF 

vaccination or smuggled CSF infected or vaccinated swine perhaps from neighboring 

countries where the virus is known to be present. 

An additional concern is continued problems with the quality of some field 

epidemiological investigations of CSF suspect cases. This problem raises the concern 

about the potential for delay or failure to investigate all possible epidemiological links, 

potentially resulting in further spread of the virus. However APHIS acknowledges the 

ongoing efforts of SENASICA to address this issue, as evidenced by its recent efforts to 

correct deficiencies with the investigations conducted in Chiapas. APHIS also 

acknowledges the ongoing enhanced surveillance activities conducted by SENASICA in 

Chiapas and other states bordering Guatemala.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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The uncertainty surrounding the serological findings leads APHIS to conclude that the 

most likely explanation for all of Mexico except Chiapas is related to residual vaccine 

titers and illegal use of vaccine. However, the pattern of findings in Chiapas along with 

its close proximity to known CSF viral activity in Guatemala prevents APHIS from 

concluding that antibody detection in Chiapas is due solely to exposure to vaccine virus.

Disease control program

Since January 2009 Mexico considers that CSF had been eradicated from the country; 

therefore it currently does not conduct an active disease control program although it 

continues to conduct CSF surveillance under the authority of the National CSF Campaign

regulation (NOM-037-ZOO-1995). The National CSF Campaign regulation provides

authority for CSF surveillance, movement control, and emergency response activities. 

The Government of Mexico considers that as of January 2009 all Mexican States 

achieved disease freedom status in accordance with the provisions of the National CSF 

Campaign. A description of the National CSF Campaign is helpful to understand the 

process utilized by Mexico in pursuit of eradication of CSF.

National Classical Swine Fever Campaign

Because of the economic importance of swine production to the country, the Mexican 

government pursued eradication of the CSF virus from the country. The Official 

Mexican Standard NOM–037–ZOO–1995, National Classical Swine Fever Campaign, 

proposed on October 11, 1995 and finalized on August 26, 1996, describes the CSF 

disease control program [34]. 

The campaign was basically directed towards domestic swine production, but its 

measures could have been applicable to feral swine if deemed appropriate by the 

Mexican government. Responsibility for the campaign was shared by SAGARPA, State 

governments, livestock protection and promotion committees, producer associations, 

owners, dealers, transporters, and other individuals and entities involved in swine 

production. 

The campaign called for the recognition of States or regions within States to be classified 

as being in one of three phases: CSF-free, eradication, or control. At the time of the 

initial site visit, May 2008, Mexico classified 6 States as being in the eradication phase, 

and 26 States, including the eight in the Central Western Region, as being CSF-free (see

Figure 3, page 27). The eradication-phase States were in central (Mexico City area) and 

southern Mexico. Inspection posts, discussed later in this document, were placed to 

protect the status of the lower risk regions from the eradication and control phase regions. 

In control phase areas, CSF vaccination was allowed and intensive vaccination programs 

were directed at high-risk and high swine population zones. In accordance with the 

NOM, vaccine production, handling, and use were subject to authorization by 

SAGARPA. Each farm was required to keep a record of vaccinations and vaccination 

certificates were issued by official or approved veterinarians. Monitoring and sentinel 

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Evaluation of the CSF Status of a Region in Mexico October 2013

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programs were implemented by SAGARPA as part of the ongoing epidemiological 

surveillance. The last control phase States or regions were in the central Mexico City area 

and in southern Mexico (see Figure 4). 

Figure 3. Epidemiological Status National CSF Campaign, 2005

Source: SAGARPA [39]

Figure 4. Epidemiological Status National CSF Campaign, 2008

 Source: SAGARPA [39]

Libre (27)

*Erradicación (6)

Control (0)

Situación de la fiebre porcina clásica

En México, 2008*

*Hasta febrero de 2008

SAGARPA

*Los 6 estados en 

erradicación están 

actualmente en 

revisión para pasar a 

fase libre en FPC

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A State or region could move into the eradication phase of the program once vaccine

marketing and use were stopped and at least12 months elapsed since the last CSF 

outbreak. In the eradication phase, the State or region was required to control animal 

movement along the main routes of entry, conduct epidemiological surveillance, 

implement a sentinel program, develop an animal health emergency plan, and fund an 

emergency insurance or indemnity program. Six months after a State or region moved 

from control to eradication phase, a sampling program was to be carried out by Federal 

and State officials, in cooperation with producer groups.

After a State or region had been in eradication phase for at least 12 months and there had

not been a case of CSF in at least the previous 24 months, it could seek recognition as 

CSF-free. A State or region would be declared CSF-free by a resolution of the Secretary 

of Agriculture and Rural Development published in the Federal Gazette. Free States 

were then required to continue to verify their status by conducting serological sampling 

surveys every six or twelve months as scheduled by SAGARPA in cooperation with State

officials.

The NOM prohibited the feeding of swill or garbage to swine throughout Mexico, 

regardless of phase in which the State or region was classified. As the Central Western 

Region prepared to seek CSF-free recognition, an education program was conducted and 

a questionnaire given to all backyard and commercial swine operations. This 

questionnaire specifically asked about feeding practices to reinforce the prohibition of 

swill or garbage feeding. 

The protection of the status of CSF-free States and the status of States under eradication 

relied on strict control of movement of swine or pork products. State governments, in 

addition to the Federal government, operated animal health checkpoints within and 

between States. The NOM basically provided that swine move only between areas of 

equal CSF risk or from higher to lower CSF risk areas. Swine from control States or 

regions were prohibited from moving into free or eradication areas. Swine from 

eradication phase areas were also prohibited from moving into free areas. Movement of 

pork and pork products were similarly regulated, except an allowance was made to move 

heat-treated products from origins of higher risk to destinations of lower risk.

In the event of suspicion of CSF, SAGARPA was to have been notified and a 

precautionary quarantine established surrounding the affected premise pending laboratory 

confirmation. In control zones, sick animals were depopulated and other swine in the 

surrounding areas were vaccinated. In free and eradication States or regions, if CSF was

confirmed the State or region was temporarily downgraded to control phase status and the 

affected and exposed premises were depopulated. If it had not been feasible to 

depopulate, the region would have reverted to control zone status and would then have 

followed the procedures established in the NOM to achieve free-zone recognition as the 

situation improves. Otherwise, affected premises were cleaned, disinfected and 

repopulated in accordance with standards outlined in the NOM. If there were no further 

evidence or suspicion of CSF during the six months following repopulation, then the free 

or eradication status of the area would be restored.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Discussion

Since January 2009, Mexico considers all of its country to be CSF-free and accordingly 

does not impose restrictions on the movement of swine, pork and pork products within 

the country on the basis of CSF.4 Therefore these commodities may move freely 

throughout Mexico’s domestic markets. 

Currently APHIS regionalizes Mexico for CSF by recognizing 9 States as being CSF-free 

and considers the remainder of the country to be affected. At the time that APHIS 

recognized these 9 States, Mexico regionalized its territory in accordance with provisions 

of the National CSF Campaign which at that time effectively provided separation of the 

regions of Mexico considered by APHIS to be CSF-free from the regions APHIS 

considered to be CSF-affected. 

Through provisions in the Code of Federal Regulations (CFR), Title 9, Section 94.32, 

APHIS imposed restrictions for pork for export from Mexico to the United States that 

require Mexico to certify that pork is derived from swine that meet three conditions. 

Those conditions are: 

1. Swine originate from regions recognized by APHIS as being CSF-free

2. Swine have not transited regions considered by APHIS to be CSF-affected

unless moved under seal

3. Swine have not commingled with swine that have been in regions considered by

APHIS to be CSF-affected

Vaccination status of the region [36-60]

Vaccination for CSF is prohibited in Mexico and CSF vaccines are not legally available. 

The veterinary infrastructure of the CFPP allows for frequent monitoring of the local feed 

stores where animal health biological agents and vaccines are marketed. It is not likely 

that the illegal sale of CSF vaccines would go undetected. If illegal vaccination occurs as 

APHIS suspects, then the vaccine is likely diverted from Mexico’s vaccine export market 

or smuggled into Mexico. In either case vaccine would likely be distributed through 

illegal and unregulated market channels.

However, illegal vaccination and the illegal import of vaccinated swine are likely 

explanations for exposure of Mexican swine to CSF antigen detected through Mexico’s 

CSF surveillance program (see discussion in section on Disease Status). 

Discussion

Since neither vaccination nor CSF virus have been confirmed in suspect cases where CSF 

antibodies were detected, then the presence of CSF virus and illegal vaccination cannot 

be excluded. Currently there is no validated diagnostic method that can distinguish 

4 Mexico enforces movement restrictions as a component of its pseudorabies eradication program.

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whether the detected CSF antibodies were from exposure to vaccine or a field strain of 

CSF virus. Because of this uncertainty explaining the source of CSF antigen exposure, 

APHIS must consider there to be an increased likelihood for release of CSF virus 

associated with this factor. 

4.4. Livestock demographics [36-60]

Mexico is an important producer of pork, currently ranked fifteen in world pork 

production and second in Central and South America after Brazil. Commercial farms are 

responsible for half of swine raised in Mexico, another 20% are produced on mediumsized (10 to 40 hogs) facilities, and 30% are raised in backyard farms (averaging 5 hogs). 

Seventy percent of pork produced is marketed fresh and the remaining 30% is processed. 

Jalisco is the largest pork producing State in Mexico; and the Jalisco, Guanajuato and 

Michoacán area in the Central Western Region is the highest concentrated swine 

production region in Mexico. The remainder of the CWR has limited commercial swine 

production. Two other States, Puebla and Veracruz, are important commercial swine 

production areas of Mexico. Table 2 lists the swine population by State. 

Table 2. Swine Production by State, 2011

State Commercial

population

Swine 

production units

Backyard 

population

Backyard

units

Aguascalientes 64,412 30 15,878 4,396

Chiapas 66,253 50 271,051 72,020

Coahuila 16,638 6 16,919 1,820

Colima 43,178 51 2,144 450

District Federal 0 0 16,427 1,000

Durango 23,070 3 22,709 7,201

Guanajuato 759,061 776 135,057 20,269

Guerrero 35,360 30 586,178 145,036

Hidalgo 57,163 64 204,757 77,566

Jalisco 2,715,841 1,177 28,586 972

Mexico 78,391 33 45,143 8,533

Michoacán 312,252 354 299,587 24,972

Morelos 111,541 22 28,544 2,994

Nuevo Leon 301,273 45 6,715 1,303

Oaxaca 44,597 38 665,733 188,512

Puebla 511,896 74 352,351 78,266

Querétaro 176,401 54 58,300 7,287

San Luís Potosí 38,289 13 113,063 30,915

Tabasco 396 1 274,658 248,348

Tamaulipas 79,431 16 96,400 23,656

Tlaxcala 21,756 29 65,020 28,286

Veracruz 969,183 125 74,257 9,282

Zacatecas 28,302 9 235,030 46,725

Source: SAGARPA [36-60]

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Central Western Region

Jalisco has the largest commercial swine industry on all the States in the Central Western 

Region. Nearly two-thirds of all commercial swine production in the region is raised in 

Jalisco; over half of all swine reared in the region if backyard herds are included. Over 

40% of commercial swine raised in the State are shipped to slaughter and sale in the 

Mexico City area (see Figure 5, page 32). Another 30% are commercially marketed 

within Jalisco which includes the densely populated city of Guadalajara. The remaining 

30% are marketed in other areas of Mexico. At the time of the site visit, there were 6 TIF 

slaughterhouses in Jalisco which produce products eligible for export and an additional 

108 municipal slaughterhouses serving the needs of local consumers. Jalisco seeks to 

develop export markets to Japan and other Asian countries. Jalisco has several major 

truck routes that are used to transit swine and pork shipped from Sonora, Sinaloa and 

other states to the north to the Mexico City area. 

Guanajuato has the second largest swine population in the Central Western Region. Most 

hog production is concentrated in the southwestern part of the state adjoining the dense 

swine production areas in Jalisco and Michoacán. A large volume (nearly 1.7 million 

hogs) transit Guanajuato heading to be slaughtered and processed in Mexico City. A 

swine semen collection center is located in an isolated area of the state removed from the 

dense swine production area. This center serves the needs of local swine producers. In

Guanajuato, there were 34 municipal slaughterhouses and 4 TIF plants. Several major 

trucking routes cross the State so there is also a high volume of hogs transiting the State 

in route to or from Mexico City.

Michoacán is the third largest swine producing state in the Central Western Region. Its 

commercial swine production area is located in the northern part of the State adjoining 

the dense swine production areas in Jalisco and Guanajuato. The southeastern area of the 

State, bordering the States of Mexico and Guerrero, has a low-density swine population 

comprised primarily of backyard swine. Approximately 30% of swine reared in 

Michoacán are for local consumption. The remaining 70% are sent out-of-state to 

consumers in the Mexico City area. Because three major interstate trucking routes cross 

the state, a large volume of live hogs and pork transit Michoacán. At the time of the site 

visit there were two swine semen collections centers and a third one under construction. 

These centers serve the needs of the local swine producers. There is one TIF plant that 

slaughters hogs and 90 municipal slaughterhouses. 

Queretaro also has a large commercial swine population, fourth largest in the Central 

Western Region. Also, a sizeable population of backyard swine is reared in this state. In 

addition to local hogs raised for commercial markets, hogs are transported from other 

states, especially Sonora, to be slaughtered and processed. There is also one TIF plant in 

Queretaro that is authorized to slaughter and process hogs imported from the United 

States. Thirty-nine percent of hogs raised in Queretaro are transported to slaughterhouses 

in the Mexico City area. Queretaro has one swine semen collection center which serves 

the needs of local producers exclusively.

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Figure 5: Swine movements into and out of Central Western Region, 2011

Source: SAGARPA [50]

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The swine population in the remaining states of the region is fairly small with limited 

commercial production. Most swine are raised for personal consumption in noncommercial backyard operations. All the slaughterhouses in these states handling swine 

are municipal slaughterhouses, none are TIF type. 

Other Mexican States

The States of Puebla and Veracruz have significant commercial swine production. 

Veracruz ranks second nationally in pork production and Puebla ranks fourth. Both are 

located east of the Mexico City population center. Veracruz has 2 TIF plants 

slaughtering swine and 13 municipal plants and Puebla has 1 TIF and 8 municipal plants. 

Swine move to and from these states to other states throughout Mexico. 

The remaining States have relatively low commercial swine production though some 

have sizeable populations of backyard swine which are reared for local or selfconsumption. Movement of local swine tends to be limited to local trips to municipal 

slaughterhouses or as sources of replacement stock. Many of these states receive swine 

for slaughter for the local market from the states with high commercial production. Also 

some states encompass major routes of interstate traffic and therefore large volumes of 

commercial swine transit the states. 

During the November 2012 site visit, APHIS visited the State of Chiapas which is located 

in southeast Mexico and borders Guatemala to the southeast. Nearly all vehicular traffic 

between Mexico and Guatemala transits Chiapas and therefore was of particular interest 

to APHIS because of the ongoing CSF viral activity in central Guatemala. Private 

airplanes travelling from Central and South America must first stop in Chiapas for 

inspection. Movement of swine and pork from Guatemala into Mexico is prohibited and 

SENASICA screens passengers and vehicles to intercept any unauthorized shipments of 

swine or pork into Mexico. However, the potential for illegal movement of swine or pork 

into Mexico from Guatemala is likely to occur through Chiapas. SENASICA has 

targeted Chiapas for enhanced CSF surveillance to increase the likelihood of early 

detection (see section on surveillance). 

Chiapas has only 50 commercial swine production units which are concentrated in the 

north and western areas of the state away from the border with Guatemala. However 

there is a sizable backyard swine population that is distributed throughout the state. 

Chiapas slaughters twice as many swine that are produced in other states than are 

produced and slaughtered within the state (see Figure 6, page 36). There are two TIF 

plants located within the state and multiple municipal plants. 

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Figure 6: Swine movements into and out of Chiapas, 2011

Source: SAGARPA [58]

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Discussion

Mexico has developed an interlinked domestic swine and pork market. Movement of 

swine and pork generally flows towards the Mexico City area in the central part of the 

country. There swine are slaughtered and pork is then redistributed back throughout the 

country. There is also extensive movement of feeder stock and replacement sows 

transiting throughout the country, with a high volume of movement of live swine through 

the CWR and central Mexico. Although these movements pose a potential means to 

quickly spread disease if the CSF virus were introduced, most of the interstate 

movements involve swine or pork derived from swine that were raised on commercial 

swine production facilities. 

During the site visits, team members visited commercial swine farms in Jalisco, 

Guanajuato, Puebla, and Chiapas. The team observed good biosecurity measures and 

record-keeping at all of the commercial swine facilities. The team also visited noncommercial small and backyard herds in Colima, Guanajuato, Jalisco, Mexico and 

Chiapas. The owners or operators of these herds seemed to have some understanding and 

awareness of the need for biosecurity and vigilance for reporting swine diseases. 

However, their knowledge was not complete and the team felt that improvements could 

be made, and encouraged the local swine association representatives to not become

complacent on the need for CSF awareness. This is especially important now that 

Mexico has completed its National CSF Campaign. 

There appeared to be good separation between commercial herds and backyard herds. 

This could serve as a key barrier to spread of CSF if reintroduced. This is especially 

important in the high density commercial swine production areas like the Central Western 

Region, as well as along routes where there is a high volume of swine movement. The 

team’s observations were consistent with the assessment of exposure risk that typically 

occurs in CSF-free countries, including the United States, where backyard herds are 

considered to have a higher likelihood of exposure to CSF virus if reintroduced than 

commercial herds. So while the commercial herds are more protected through greater 

biosecurity measures, the potential exposure of backyard herds is more likely. Therefore, 

as discussed in greater detail in the section on surveillance, targeted monitoring of 

backyard herds should be an essential strategy adopted to quickly detect a reintroduction 

of CSF into a CSF-free region. APHIS could not identify any other concerns related to 

this factor that should be considered in the risk estimation.

4.5. Epidemiological separation from potential sources of infection [36-60]

Disease status of adjacent regions

Mexico borders the United States in the north. The United States has been free of CSF 

since 1976.

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Mexico shares its southern international border with Guatemala and Belize. APHIS 

currently considers both countries to be affected with CSF. Guatemala is currently 

experiencing an epidemic of CSF and Belize reported its last case of CSF in 1988 [65]. 

Currently, APHIS considers the States of Baja California, Baja California Sur, 

Campeche, Chihuahua, Nayarit, Quintana Roo, Sinaloa, Sonora, and Yucatan to be CSFfree. The remainder of Mexico is the subject of this evaluation. 

Discussion

The existence of common land borders with CSF-affected regions in the south presents a 

risk for re-introducing CSF into Mexico (see discussion in previous section). However, 

Mexico prohibits the importation of swine, pork and pork products from countries it 

considers to be CSF-affected, including Belize and Guatemala.

Natural and manmade barriers

Mexico benefits from natural barriers to disease transmission from its location between 

the Gulf of Mexico on the east, the Caribbean Sea on the southeast and the Pacific Ocean 

to the west. Mexico has two land borders, the northern border with the United States and 

the southern border with Belize and Guatemala. The United States has been CSF-free 

since 1978; therefore, Mexico’s northern border is not adjacent to a region of higher risk. 

So only the southern border of Mexico is considered to be adjacent to regions of higher 

risk. 

The Mexican State of Quintana Roo borders Belize to the south. Belize has not reported 

a CSF outbreak since 1988; however since APHIS has not conducted an evaluation of 

their CSF status, APHIS considers Belize to be CSF-affected [65]. APHIS has 

previously evaluated the CSF exclusion activities of Mexico along its border with Belize 

as part of its evaluation of the CSF-status of Quintana Roo. In those reviews, APHIS did 

not identify any concerns which required additional mitigations. 

The Mexican States of Campeche, Chiapas, and Tabasco border Guatemala. Recently 

Guatemala has been experiencing outbreaks of CSF in the central part of the country 

where most of the country’s swine production occurs. CSF is considered endemic in this 

area [65]. The swine industry in Guatemala is small particularly in comparison to 

Mexico. 

In response to this outbreak, Guatemala has vaccinated extensively along the borders 

with Mexico, Honduras, and El Salvador using the PAV-250 vaccine to create a sanitary 

buffer zone. Presently, the government of Guatemala is conducting a vaccination 

campaign of all production sectors in the central area of the country.

Much of Mexico’s border with Guatemala (all of the border between Campeche, Tabasco 

and much of Chiapas) fronts the Petén area of Guatemala which is a sparsely-populated 

rainforest with very limited number of highway entry points and a very low swine 

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population. Feral swine have not been reported in this area and domestic swine 

populations are very low. During the current outbreak, the Petén area has maintained an 

absence of suspected cases and has produced only negative results to samples collected 

for the CSF serological survey [58, 65]. Therefore APHIS considers that the Petén area 

serves as a limited natural barrier to disease transmission from Guatemala to Mexico. 

The remainder of Mexico’s border with Guatemala courses through a very mountainous 

region in the State of Chiapas westward to the Pacific Ocean. There are a limited number 

of highway and railway crossings between the two countries along this border. Mexico 

operates a system of border crossing and internal livestock and agricultural product 

inspection checkpoints, both federal and state, which have provided the means to control 

movements of animals and animal products. Checkpoints exist along highways, as well 

as at seaports and airports. These will be discussed later in the next section on movement 

controls.

Discussion

Without a complete natural barrier limiting the movement of swine and products into 

Mexico, separation from adjacent regions of higher risk is dependent upon movement 

controls discussed in the next section.

Movement controls and biosecurity from higher-risk regions

Since January 2009, Mexico has considered its entire territory to be CSF-free and 

therefore removed all CSF-related restrictions on the movement of swine, pork and pork 

products within the country.5 However the authority to impose movement restrictions for 

the control of CSF remains as long as NOM-037-ZOO-1995 remains in effect. 

Presumably this authority would be exercised if a CSF outbreak occurred and if any 

region within Mexico were to lose its CSF-free status. NOM-037-ZOO-1995 also 

granted SENASICA authority to prohibit the import of swine, pork or pork products from 

countries or regions considered by Mexico to be CSF-affected, unless the pork or pork 

products were heat-treated sufficiently to inactivate CSF virus. The draft regulatory 

instrument, discussed in Section 4.2 which is to replace NOM-037-ZOO-1995, will 

preserve SENASICA’s authority to continue to restrict imports from CSF-affected 

regions and to impose appropriate movement controls in the event of a CSF outbreak. 

The authority under NOM-037-ZOO-1995 allowed CSF-free States to restrict movement 

of swine, pork and pork products from States that were in eradication or control phases in 

accordance with proscribed standards. Only live swine and fresh pork from other CSFfree States were allowed entry or transit through other CSF-free States. Vehicles that 

moved live swine through CSF-affected zones must have been cleaned and disinfected 

prior to return through a free zone. 

5 Mexico enforces movement restrictions as a component of its pseudorabies eradication program.

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Processed pork products from eradication or control phase zones could enter CSF-free 

zones if they were shipped from Federal inspection type establishments (TIF plants) 

under these conditions: 1) the facility must have had a current TIF registration; 2) the 

TIF plant must have been authorized by DGSA to market their products and byproducts 

into CSF-free zones; 3) these products must have been processed according to the heat 

treatment standards described in the NOM (68.9o C for 30 minutes or 80.5o C for 3 

minutes); 4) a veterinary certificate must have accompanied these consignments; and 5) 

the consignments must have been properly identified, and must have moved via sealed 

vehicles. Typically these were products produced in the TIF plants in the Mexico City 

area and were shipped to the markets in other areas of the country.

Other regulatory authorities allow SENASICA to require that veterinary health 

certificates be issued for interstate movement of live swine. The health certificate is 

required to accompany those shipments. 

Mexico enforces animal and animal product movement restrictions through a series of 

inspection control posts, collectively referred to as the Sistema Nacional de Cuarentena 

Agropecuaria, or National System for Agricultural Quarantine. These inspection control 

posts are authorized by DGIF and managed by SAGARPA, the state, or jointly. This 

system included inspection posts controlling movements into Mexico from third 

countries, referred to as “exterior quarantine”; movements within Mexico based on 

regional strategies, the “interior quarantine”; and movements within and between States. 

The exterior quarantine is considered the first line of defense to prevent animal diseases, 

exotic to the country, from entering Mexico. Compliance with the import standards and 

phytosanitary requirements is verified through pre-clearance activities, document checks 

and physical inspections of animals and animal products. This activity is performed 

through by livestock health inspection personnel at maritime ports, international airports 

and along international borders. 

To assist with the eradication campaigns for and control of various animal and plant 

health diseases which exist in the country, Mexico developed a system of internal 

quarantine cordons (see Figure 7, page 39). There are 5 cordons effectively controlling 

movements between 6 zones within Mexico. These cordons consist of 43 control points 

staffed and managed by SAGARPA. The strategic purpose of these cordons is to prevent 

diseases, which exist within the national territory, from spreading from the infected areas 

to the disease free areas and were integral in the CSF eradication campaign. 

In addition to the cordon inspection posts, there are also numerous permanent inspection 

posts operated and staffed by CFPP personnel. These inspection posts are located on 

most major roadways that transit a State and operate 24 hours a day to control intra- and 

interstate movement of animals and animal products. These veterinary inspectors 

undergo additional training in order to be certified in movement control. The purpose of 

these inspection posts is to verify compliance with animal health regulations and laws, to 

contribute to disease control and eradication programs, to prevent the spread of disease in 

the event of disease outbreak; and to maintain disease-free zones. 

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Figure 7: Phyto and zoosanitary quarantine lines

Source: SAGARPA [40]

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Discussion

The APHIS site visit team visited inspection posts throughout the country, including 

CFPP-operated posts, federal cordon inspection posts, and international checkpoints at 

maritime ports, international airports and land border crossings. 

At the internal inspection posts, physical and documentary inspection was performed on 

all readily identifiable animal and animal product shipments. Physical inspections mainly 

focus on verifying that the animals in transit matched the health certificate documents. 

Health certificate documents are issued only if the animals listed are free of signs of 

communicable diseases. At the inspection posts, unless there are obvious health 

problems, such as dead animals, the vehicles continue on to their destination. If the 

destination is a slaughterhouse, the animals are clinically inspected upon arrival. 

Inspectors indicated that if vehicles with live animals or animal products did not stop, 

then the inspectors with the assistance of law enforcement officers would pursue and stop 

these vehicles to return to the post for inspection. In addition, other vehicles, including 

passenger cars and buses, were inspected randomly. Records were maintained at the 

inspection posts in a log of all consignments transiting the post. The records indicated 

that any incoming swine, pork or pork products not in compliance with established 

regulations were rejected and returned to their point of origin. Monthly summary reports 

were submitted to the CFPP office. 

During the site visits, APHIS officials visited the international inspection control posts at 

the international airports in Mexico City, Guadalajara (Jalisco), Tuxtla and Tapachula 

(Chiapas). The primary CSF risk of international air traffic into Mexico relates to 

passenger service rather than freight shipments since Mexico primarily only imports 

swine, pork and pork products from the United States or Canada. The passenger-related 

risk would be associated with passengers carrying pork or pork products for their own 

consumption. These commodities could possibly contain CSF-contaminated material. 

The APHIS team did not observe any deficiencies with the inspection facility, personnel 

or procedures. One potential concern that the APHIS team observed was the provision 

that a passenger could request that products prohibited entry into Mexico be stored and 

returned to the passenger when they departed Mexico. While the APHIS team observed 

good control over these held products, the team felt that the practice presented an 

unnecessary risk of potential exposure through cross-contamination.

APHIS also visited the seaports at Manzanillo, Colima and Tapachula, Chiapas. Again 

there was no movement of live swine and very little movement of pork or pork products 

through these seaports. APHIS visited the land border inspection post at Tapachula, 

Chiapas which is the primary crossing for vehicles traveling into Mexico from 

Guatemala. APHIS could not identify any concerns or deficiencies with the operations 

and inspections conducted at these inspection posts.

APHIS considers Mexico’s system of inspection posts, both internal and international, to 

be a strong point in the country’s animal health control infrastructure.

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4.6. Diagnostic laboratory capabilities [36-60]

Mexico has 3 national reference laboratories: CENASA (National Animal Health 

Diagnostic Services), CPA (Mexico/USA Commission for the Prevention of FMD and 

other Exotic Animal Diseases), and CENAPA (National Animal Health Reference 

Diagnostic Services). All three are Directorates within SAGARPA and answer directly 

to SENASICA.

CENASA is responsible for the planning, organization, direction, support and evaluation

of animal health services and laboratories, and the evaluation of biological and chemical 

products for veterinary use. It develops and produces diagnostic reagents for enzootic 

diseases and for epidemiological surveillance, in particular, pseudorabies, bovine 

tuberculosis, brucellosis, Newcastle Disease and avian influenza. Prior to the January 

2009 declaration of CSF disease-freedom by Mexico, CENASA was also responsible for 

CSF surveillance; however that responsibility has now shifted to CPA. CENASA also is 

responsible for the training and accreditation of laboratory personnel.

CPA operates a laboratory with level three biosafety (BSL3) located at Palo Alto which is 

the reference laboratory for exotic diseases in Mexico, which now includes CSF. CPA 

has recently constructed and staffed a network of 13 biosafety level two laboratories 

(BSL2) which are responsible for testing all CSF serological surveillance samples 

throughout Mexico. CPA’s BSL3 laboratory at Palo Alto is responsible for doing the 

confirmatory testing on any serological samples testing positive on the initial screening 

tests and to conduct all diagnostic testing for CSF antigen and viral isolation and 

sequencing.

CPA also deals with risk assessments, contingency plans, keeps SAGARPA updated on 

the national and world-wide animal health situation, lays down sanitary import conditions 

for animals and animal products and is a liaison with international reference laboratories 

regarding exotic diseases (e.g. FMD). It develops training programs on exotic disease 

controls.

CENAPA is the national reference laboratory for pharmaceutical and chemical products,

residues and parasitology. It establishes standards and procedures, validates methods of 

analysis, analyses samples from TIF establishments, lays down tolerances for residues for

particular tissues and accredits private laboratories within its field of competence.

CSF Diagnostic Competency

In 2008, APHIS conducted a site visit to the CWR of Mexico. At that time, CSF 

diagnostics were handled by state and private laboratories with CENASA being the 

confirmatory laboratory. During that visit, VS identified concerns with laboratory 

diagnostic competencies related to the use of inconsistent and variable diagnostic 

procedures. In January 2009 when Mexico declared CSF had been eradicated from the 

country, the disease was considered to be exotic and accordingly the diagnostic 

responsibility shifted to the CPA laboratory network.

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During 2011 at the request of SENASICA, APHIS provided technical assistance 

regarding CSF laboratory diagnostic protocols and techniques, field investigation 

methodology and surveillance strategy. As a result of this joint effort, Mexico developed 

a national standard protocol for appropriate laboratory procedures and epidemiologic 

follow-up to positive serological findings utilizing a standardized diagnostic protocol.

In the fall of 2011 personnel from APHIS’ Foreign Animal Disease Diagnostic 

Laboratory (FADDL) at Plum Island extensively reviewed SENASICA’s laboratory 

network and their findings (from training, site visits, document reviews, and proficiency 

panel testing) were favorable. FADDL reviewed the BSL3 laboratory at Palo Alto and 

verified their competency to conduct CSF confirmatory testing with an effective date of 

Sept. 13, 2011 (see Appendix 1). APHIS considers confirmatory tests conducted after 

that date to be valid. FADDL technicians also reviewed several CPA BSL2 laboratories 

in Jalisco, Sonora, Puebla, Chiapas, and Veracruz, during multiple site visits conducted 

from February 2011 through December 2012 and verified their compliance with 

established diagnostic protocols.

Discussion

APHIS is satisfied with the improvements made to Mexico’s CSF diagnostic capabilities 

and is confident in the CSF test results reported by CPA on samples processed after 

September 13, 2011. CPA personnel have demonstrated proficiency in CSF diagnostics 

and the CSF confirmatory processes and procedures are in compliance with international 

standards. While APHIS has confidence in the diagnostic test results, in many of these 

suspect cases, investigators did not collect the most appropriate samples or, due to lack of

reliable animal identification, it could not be verified that the samples they collected were 

taken from animals most likely to be harboring the virus (if it were present) at the time of 

collection.

4.7. Surveillance practices [36-60]

Active surveillance

An active CSF surveillance program is conducted in Mexico under the authority of 

NOM-037-ZOO-1995. States maintain their CSF-free status by conducting annual 

serological sampling surveys in commercial and backyard herds. In addition, 

SENASICA also collects samples for slaughterhouse surveillance. Each year 

SENASICA determines the CSF sampling targets for each state and coordinates the 

implementation with State governments and CFPP based on the state’s swine population 

and risk considerations. Since the 2009 declaration of disease freedom, SENASICA has 

been reducing annually the number of samples collected for CSF surveillance, except for 

increased targeted surveillance conducted along Mexico’s southern border in response to 

the CSF outbreak occurring in Guatemala.

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At the time of the site visit to the CWR in April 2012, the CSF surveillance sampling for 

commercial herds that SENASICA was following for the 2012 survey was designed to 

detect 3% threshold premises level prevalence with 99.9% confidence, assuming a test 

sensitivity of 98% based on the national swine population. However after considering a 

recommendation by the APHIS team, SENASICA adjusted the sampling targets to 

achieve a detection threshold of 1% prevalence with 95% confidence level for the CWR.

APHIS recommended more intensive surveillance of the region because of the region’s 

high concentration of commercial swine farms and large swine population. The CWR is 

more likely than other regions to export pork. 

A stratified random sampling protocol was used for the backyard herds to detect 1%

prevalence with 97% confidence. SENASICA determined the number of backyard herd 

samples to collect annually in each State. SENASICA provides guidance to State and 

Committees on risk-based selection factors so they can target sampling selections.

Usually five pigs per backyard herd were sampled or all pigs are sampled if there are less 

than 5 pigs on the premises. 

For the last couple of years, SENASICA has conducted slaughter surveillance in TIF 

slaughter plants and in 2012 began collecting samples in municipal plants as well. 

SENASICA selects which plants to sample based on their assessment of risk factors and 

establishes a target number for samples to collect from each plant. The SENASCIA 

inspectors at each plant developed their own selection criteria to choose which lots to 

sample and when. The APHIS team found variability between the slaughterhouses in the 

selection criteria they followed; generally inspectors selected lots and animals to sample 

based on convenience.

Summaries of the surveillance sampling scheme by State for the last two years are 

provided in Tables 3 and 4 (pages 44-45). The diagnostic test results of positive or 

suspicious findings for the active surveillance are listed in Table 5 (page 46). 

Passive surveillance

The level of passive surveillance activity varied among the States under evaluation. In 

general states that have either a large swine populations or have most recently gained 

their CSF-free designation were more likely than other States to report passive 

surveillance investigations. The diagnostic test results from passive surveillance 

investigations are summarized by State in Table 6 (page 47).

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Table 3. CSF surveillance sampling scheme, 2011

STATE

Commercial Backyard Slaughterhouses Hunting Reserves

#

Units

#

Samples

#

Units

#

Samples

#

Units

#

Samples

#

Units

#

Samples

Aguascalientes 7 294 60 300 0 0 n/a n/a

Chiapas 13 546 90 450 0 0 0 0

Coahuila 1 42 60 300 1 84 n/a n/a

Colima 12 504 60 300 n/a n/a 1 5

District Federal n/a n/a 60 300 n/a n/a n/a n/a

Durango 3 126 90 450 2 22 n/a n/a

Guanajuato 186 7,812 60 300 4 444 n/a n/a

Guerrero 7 294 60 300 0 0 n/a n/a

Hidalgo 16 672 60 300 0 0 0 0

Jalisco 271 11,382 60 300 2 72 0 0

Mexico 8 336 60 300 3 648 0 0

Michoacán 84 3,444 60 300 0 0 n/a n/a

Morelos 5 210 60 300 n/a n/a n/a n/a

Nuevo Leon 14 588 60 300 2 468 n/a n/a

Oaxaca 9 378 60 300 0 0 n/a n/a

Puebla 17 714 60 300 1 120 0 0

Querétaro 13 546 60 300 1 216 n/a n/a

San Luís Potosí 3 126 60 300 0 0 n/a n/a

Tabasco 1 42 90 450 n/a n/a n/a n/a

Tamaulipas 6 252 60 300 0 0 n/a n/a

Tlaxcala 7 245 60 300 0 0 0 0

Veracruz 30 1260 60 300 1 84 1 5

Zacatecas 2 84 60 300 0 0 0 0

Source: SAGARPA [49-60]

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Table 4. CSF surveillance sampling scheme, 2012

STATE

Commercial Backyard Slaughterhouses Hunting Reserves

#

Units

# 

Samples

#

Units

# 

Samples

#

Units

#

Samples

#

Units

#

Samples

Aguascalientes 2 84 30 150 1 120 n/a n/a

Chiapas 2 84 120 863 2 134 1 5

Coahuila 1 42 30 150 2 240 n/a n/a

Colima 3 126 30 150 1 120 0 0

District Federal n/a n/a 30 150 n/a n/a n/a n/a

Durango 2 84 60 300 3 300 n/a n/a

Guanajuato 49 2,058 60 300 9 840 n/a n/a

Guerrero 2 84 30 150 2 180 n/a n/a

Hidalgo 4 168 30 150 1 120 1 5

Jalisco 74 3,108 60 300 26 2,760 2 10

Mexico 3 126 30 150 5 420 3 15

Michoacán 20 840 60 300 6 660 0 0

Morelos 1 42 30 150 1 120 n/a n/a

Nuevo Leon 3 126 30 150 2 180 n/a n/a

Oaxaca 2 84 30 150 1 120 n/a n/a

Puebla 4 168 30 150 3 400 2 10

Querétaro 3 126 30 150 2 180 n/a n/a

San Luís Potosí 1 42 30 150 1 120 n/a n/a

Tabasco 1 42 89 445 n/a n/a n/a n/a

Tamaulipas 1 42 30 150 2 240 n/a n/a

Tlaxcala 1 42 30 150 1 120 3 15

Veracruz 7 294 30 150 3 300 1 5

Zacatecas 1 42 30 150 1 120 1 5

Source: SAGARPA [49-60]

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Table 5. Active CSF surveillance samples with positive serological findings, 2011-

2012

STATE YEAR Prod.Unit 

(PU)

POSITIVE 

SAMPLES ELISA

POSITIVE 

SAMPLES IP

POSITIVE 

SAMPLES SN

POSITIVE 

SAMPLES RTPCR

POSITIVE 

SAMPLES VI

Aguascalientes 2011 1 1 0 n/a 0 n/a

2012* - - - - - 0

Chiapas 2011 103 1 0 n/a 0 n/a

2012* 219 11 8 7 0 n/a

Coahuila 2011 61 0 n/a n/a 0 n/a

2012* 8 0 n/a n/a 0 n/a

Colima 2011 1 1 1 0 0 0

2012** 1 9 7 1 0 0

District Federal 2011 0 n/a n/a n/a n/a n/a

2012* 0 n/a n/a n/a n/a n/a

Durango 2011 125 0 n/a n/a 0 n/a

2012* 56 0 n/a n/a 0 n/a

Guanajuato 2011 5 11 9 7 0 0

2012* - - - - - -

Guerrero 2011 67 1 1 1 0 0

2012* 34 0 n/a n/a n/a n/a

Hidalgo 2011 76 14 12 8 0 0

2012* 443 0 n/a n/a 0 n/a

Jalisco 2011 25 37 5 1 0 0

2012* - - - - - -

Mexico 2011 5 24 18 16 0 0

2012* 4 4 0 n/a n/a n/a

Michoacán 2011 11 22 7 1 0 0

2012* - - - - - -

Morelos 2011 65 1 1 1 0 0

2012* 32 4 2 0 0 0

Nuevo Leon 2011 0 n/a n/a n/a n/a n/a

2012* 1 47 35 0 n/a 0

Oaxaca 2011 75 2 0 n/a 0 n/a

2012* 33 0 n/a n/a 0 n/a

Puebla 2011 78 0 n/a n/a n/a n/a

2012* 33 1 0 n/a n/a n/a

Querétaro 2011 2 2 0 n/a n/a n/a

2012* - - - - - -

San Luís Potosí 2011 0 n/a n/a n/a n/a n/a

2012* - - - - - -

Tabasco 2011 92 0 n/a n/a n/a n/a

2012* 91 1 1 1 0 0

Tamaulipas 2011 66 0 n/a n/a n/a n/a

2012* 33 0 n/a n/a n/a n/a

Tlaxcala 2011 67 0 n/a n/a n/a n/a

2012* 19 2 2 0 0 0

Veracruz 2011 91 2 2 0 0 0

2012* 41 0 0 0 0 0

Zacatecas 2011 0 0 n/a n/a n/a n/a

2012* - - - - - -

- data not available at time of site visit

* January to September 2012

** January to May 2012

Source: SAGARPA [49-60]

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Table 6. Passive CSF surveillance samples with positive serological findings, 2011-

2012

STATE YEAR Prod.Unit (PU) SAMPLES 

TAKEN

POSITIVE 

SAMPLES 

ELISA

POSITIVE 

SAMPLES 

IP

POSITIVE 

SAMPLES 

SN

POSITIVE 

SAMPLES 

RT-PCR

POSITIVE 

SAMPLES 

VI

Aguascalientes 2011 0 0 n/a n/a n/a n/a n/a

2012* - - - - - - -

Chiapas 2011 5 68 0 n/a n/a 0 n/a

2012* 7 84 0 n/a n/a 0 n/a

Coahuila 2011 0 0 n/a n/a n/a n/a n/a

2012* 0 0 n/a n/a n/a n/a n/a

Colima 2011 0 0 n/a n/a n/a n/a n/a

2012* - - - - - - -

District Federal 2011 2 21 0 n/a n/a 0 0

2012* 0 0 n/a n/a n/a n/a n/a

Durango 2011 0 0 n/a n/a n/a n/a n/a

2012* 0 0 n/a n/a n/a n/a n/a

Guanajuato 2011 1 10 0 n/a n/a 0 n/a

2012* - - - - - - -

Guerrero 2011 1 2 n/a n/a n/a 0 n/a

2012* 5 37 0 n/a n/a 0 n/a

Hidalgo 2011 3 92 0 n/a n/a 0 0

2012* 0 0 n/a n/a n/a n/a n/a

Jalisco 2011 6 238 0 n/a n/a 0 0

2012* - - - - - - -

Mexico 2011 6 449 18 14 12 0 0

2012* 0 0 n/a n/a n/a n/a n/a

Michoacán 2011 0 0 n/a n/a n/a n/a n/a

2012* - - - - - - -

Morelos 2011 1 5 0 n/a n/a n/a n/a

2012* 10 48 0 n/a n/a 0 0

Nuevo Leon 2011 0 0 n/a n/a n/a n/a n/a

2012* 0 0 n/a n/a n/a n/a n/a

Oaxaca 2011 2 7 0 n/a n/a n/a n/a

2012* 2 17 0 n/a n/a 0 n/a

Puebla 2011 1 4 n/a n/a n/a 0 n/a

2012* 0 0 n/a n/a n/a n/a n/a

Querétaro 2011 2 - 0 n/a n/a 0 0

2012* - - - - - - -

San Luís Potosí 2011 0 0 n/a n/a n/a n/a n/a

2012* - - - - - - -

Tabasco 2011 3 16 0 n/a n/a 0 0

2012* 6 40 0 n/a n/a 0 0

Tamaulipas 2011 0 0 n/a n/a n/a n/a n/a

2012* 2 10 0 n/a n/a n/a n/a

Tlaxcala 2011 1 3 0 0 0 0 0

2012* 0 0 n/a n/a n/a n/a n/a

Veracruz 2011 0 0 0 0 0 0 0

2012* 0 0 0 0 0 0 0

Zacatecas 2011 2 10 0 n/a n/a n/a n/a

2012* - - - - - - -

- data not available at time of site visit

* January to September 2012

** January to May 2012

Source: SAGARPA [49-60]

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In accordance with NOM-037-ZOO-1995, when a positive result is obtained through 

serological screening tests, or when a case of CSF is suspected on a farm, the animal 

owner, the attending veterinarian, and the laboratory are required by Federal law to 

immediately report the suspicion or finding to the SAGARPA State delegation. 

Immediately upon suspicion, a precautionary quarantine is to be imposed on the affected 

premises and an official epidemiological investigation is to be conducted. 

The APHIS site visit team examined multiple case investigation reports in each of the 

states visited. The results of those audits are discussed previously in this document (see

discussion in Section 4.3. Disease history and vaccination practices).

Discussion

The implication regarding the findings of exposure to CSF antigen from an undetermined 

source was previously discussed and will be considered in the subsequent risk estimation. 

However it is important to point out that until the source of these exposures is determined 

APHIS considers it necessary for Mexico to maintain the current level of CSF 

surveillance, especially if targeted surveillance strategies can be utilized to further 

leverage the necessary resource investment.

During the site visits, the APHIS team made several specific recommendations regarding 

surveillance which are: 

• For backyard and semi-technified farms, the guidance given to field personnel 

collecting samples should emphasize that the sample size of 5 is a minimum 

sample size, and that field personnel should use their discretion to collect more 

samples from larger farms in this category.

• One epidemiologic unit should be considered one sampling unit. Field personnel 

should not collect samples from multiple owners within an epidemiologic unit for 

the purpose of filling the sampling quota. 

• For slaughter surveillance, sick animals and dead animals (any cause) should be 

selected, if available. APHIS recommended that any animals that die in the 

slaughter channel should be sampled and tested for CSF. Antigen tests are 

appropriate for testing sick and dead animals. 

• If no sick or dead animals are available, slaughter surveillance samples should be 

selected randomly from multiple lots, rather than from a single lot. Antibody tests 

are appropriate for animals with no clinical signs.

• The records examined indicated that laboratory diagnosticians were often not 

included in the investigation process. Consistent and systematic communication 

between laboratory diagnosticians, field investigators, and SENASICA, 

Epidemiological Surveillance Direction (DIVE) are beneficial to fully understand 

the epidemiology of each case investigation. APHIS recommends that all parties 

be consulted in the case investigation process prior to closing a case. 

Although some of the findings detected through Mexico’s CSF surveillance program 

raise concern, APHIS acknowledges that the capacity to make those detections are a 

credit to the strength of the program which APHIS believes to be sound. 

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4.8. Emergency preparedness and response [36-60]

In general whenever an animal disease exotic to Mexico, including CSF, is detected it 

must be immediately reported to the Secretariat of Agriculture and Rural Development in 

accordance with NOM-046-ZOO-1995. This NOM describes an animal health emergency

infrastructure that would be activated.

DINESA is the National Mechanism for Emergencies in Animal Health (Dispositivo 

Nacional de Emergencia de Salud Animal), which is activated once the presence of an 

exotic disease or pest is confirmed within the national territory, according to the general 

and/or specific emergency plan to control and-or eradicate the exotic disease in case. 

DINESA requests the collaboration of different Federal or State Branch Offices in order 

to contain the outbreak and avoid serious national economic losses.

Mexico has an established national system for surveillance and reporting of exotic animal 

diseases operated by SAGARPA in collaboration with the Mexico-United States

Commission for the Prevention of Foot and Mouth Disease and Other Exotic Animal 

Diseases (CPA). Since the January 2009 declaration, CSF virus is considered to be 

exotic to all of Mexico. 

Operating at the State level under the direction of DINESA, are the Grupos Estatales de 

Emergencia en Salud Animal (State Animal Health Emergency Groups, GEESAs). In the 

event of an animal emergency, a GEESA is activated to function at the local level to 

quickly and effectively respond to the outbreak. A GEESA includes specialized technical 

personnel who have experience with animal health and outbreak control. This group is 

composed of individuals from Federal and State government, CFPP, industry, and swine 

producers. The GEESA includes both official and private veterinarians who receive 

periodic training in foreign animal diseases and participate in simulation exercises. If 

necessary, the military can assist the GEESA in animal health emergencies. 

Under the authority of NOM-037-ZOO-1995 whenever CSF is suspected, SAGARPA

must immediately be notified and a precautionary quarantine is to be implemented in the 

focal and perifocal area to include the affected, exposed and at risk premises. Field 

investigations are coordinated by CPA through their regional network of field 

epidemiologists. CPA works with State authorities to conduct this activity. If CSF is 

confirmed by the CPA laboratory then the quarantine would become definitive. 

Movement controls are to be implemented, sick animals are to be killed, dead animals are 

to be sanitarily disposed, and an epidemiological investigation is to commence. The

Dispositivo Nacional de Emergencia de Sanidad Animal (National Animal Health 

Emergency Operation or DINESA) is to be activated. DINESA functions to control and 

eradicate the outbreak in accordance with the National CSF Emergency Plan. 

Under the current authority, once the extent of the outbreak is known, a determination 

will be made to assess the financial and technical feasibility of depopulating affected and 

exposed premises. If feasible, a stamping-out without vaccination policy will be 

implemented and indemnity will be paid to producers, likely out of the State’s insurance 

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plan or contingency fund. If depopulation is not feasible, then SENASICA has the option 

to downgrade the CSF-status of the State from “CSF-free zone” to “CSF-control zone”

status, designations utilized during Mexico’s National CSF Campaign. Those states 

would then have to follow procedures established in NOM-037-ZOO-1995 to regain 

“CSF-free zone” recognition as the situation improved. If a stamping out without 

vaccination policy is implemented and the affected premises are cleaned, disinfected and

repopulated in accordance with the National CSF Emergency Plan, then six months must 

pass without evidence of CSF virus before the State could regain the “CSF free-zone”

status.

Discussion

The APHIS site visit team observed a close association and cooperation between the 

Federal, State and municipal government officials, the CFPP staff and swine producers. 

This cooperation was especially effective in the operation of animal health checkpoints

which would provide an effective means to control swine movements in the event of a 

CSF outbreak. 

As discussed in a previous section, APHIS is concerned about the thoroughness of tracein and trace-out activities of some suspect case investigations. APHIS has consistently 

recommended to SENASICA that improvements be made in this regard. This problem 

has the potential to allow pockets of CSF virus to go undetected and potentially spread 

further. The result of such would certainly complicate any emergency response once the 

outbreak is detected. Otherwise, APHIS could not identify any other concerns with this 

factor.

4.9. Release Assessment Conclusions

Serologic evidence of exposure to CSF virus has been found in a number of Mexican 

States. The specificity of the antibodies was demonstrated by comparative neutralization 

tests; however, no virus has been detected. It has not been possible from the data 

available to determine whether these antibodies were produced after infection with a field 

strain of CSF virus or after vaccination with CSF vaccine. These findings increase the 

level of uncertainty regarding the presence or absence of CSF virus in Mexico. 

APHIS considers three possible explanations for the high serum neutralization (SN) titers 

found in the sera of pigs during several active and passive surveillance investigations: 

exposure to CSF vaccine virus; exposure to field strain CSF virus; and false positive test 

results. 

APHIS concludes that for all of Mexico except Chiapas the most likely explanation for 

the serological findings is residual vaccine titers and/or continued illegal use of vaccine. 

However, the pattern of findings in Chiapas, along with its close proximity to known CSF 

viral activity in Guatemala, prevents APHIS from concluding that antibody detection in 

Chiapas is due solely to exposure to vaccine virus. 

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Although APHIS is unable to recognize these States as free of CSF due to the uncertainty 

surrounding the serological findings, APHIS concludes that the risk of importing CSFinfected pork and pork products from the currently unrecognized States of Mexico, with 

the exception of Chiapas, is low and can be mitigated if certain requirements are met on 

the farms of origin and in the slaughterhouses and processing plants. These requirements 

are described below under Mitigations.

APHIS observed many strong points in Mexico’s veterinary infrastructure, diagnostic 

laboratory network, and commercial farm biosecurity. While finding evidence of CSF 

antigen exposure detected through Mexico’s CSF surveillance program raises concern, 

APHIS recognizes that the capacity to make those detections are a credit to the strength 

of the surveillance program which APHIS believes is sound at the current level. APHIS 

also acknowledges the ongoing enhanced surveillance activities conducted by 

SENASICA in Chiapas and other states bordering Guatemala in response to the CSF 

outbreaks there. APHIS also considers Mexico’s system of inspection posts, both 

internal and international, to be a strong point in the country’s animal health control 

infrastructure.

However, APHIS identified three risk factors associated with importing Mexican-origin

pork and pork products into the United States from a region in Mexico. APHIS 

discusses these risk factors in the context of the potential for counterbalancing 

circumstances or applying appropriate risk mitigations to further reduce the risk of 

introducing and establishing CSF in the United States. The risk mitigation procedures, 

which will be defined in the proposed rule, include regionalization of Mexico to 

recognize a CSF-low-risk region and certifications by SENASICA to provide confidence 

that pork and pork products meet acceptable export criteria. The CSF-low-risk region in

Mexico recognized by APHIS includes all of Mexico except the 9-states currently 

recognized as CSF-free and the State of Chiapas for which APHIS considers the CSF risk 

to be unacceptable.

Risk Factors 

Uncertainty regarding positive serological results

Serologic evidence of exposure to CSF virus has been found in a number of Mexican 

States as recently as 2012. The specificity of the antibodies was demonstrated by 

comparative neutralization tests; however, no virus has been detected. It has not been 

possible from the data available to determine whether these antibodies were produced 

after infection with a field strain of CSF virus or after vaccination with CSF vaccine. So 

far, antigen test results (i.e. PCR and viral isolation) have been negative. However, it is 

difficult to conclude that CSF virus is absent in these suspect cases because investigators 

did not collect or, due to lack of reliable animal identification, it could not be verified that 

they collected the most appropriate samples from the animals most likely to be harboring 

the virus (if it were present) at the time of collection.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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Therefore because the presence of CSF antibody detection in multiple areas of Mexico 

cannot be explained by the evidence presented, APHIS concluded that these findings

increase the level of uncertainty regarding the presence or absence of CSF virus in the 

country. 

For all states but the State of Chiapas, APHIS considers the most likely explanation for 

the CSF antigen exposure is related to residual vaccine titers and illegal use of vaccine. 

However, the pattern of findings in Chiapas, along with its close proximity to known CSF 

viral activity in Guatemala, prevents APHIS from considering it to be likely that antibody 

detection in Chiapas is due solely to exposure to vaccine virus. 

APHIS considers the CSF-status of Chiapas to be higher risk than the rest of Mexico for 

several reasons. In 2012, SENASICA identified a cluster of 7 premises where extremely 

high CSF antibody titers (most in excess of 1:2560) were detected. These titers are 

indicative of CSF antigen exposure but the nature of the exposure is unexplained. These 

premises are located in close proximity to the border with Guatemala where CSF 

outbreaks have recently occurred. SENASICA recognizes that Chiapas as a high risk 

region where CSF is more likely to be reintroduced and accordingly has targeted the state 

for increased surveillance. 

All vehicular traffic between Guatemala and Mexico enters through Chiapas. 

SENASICA maintains several inspection posts along those highways that serve as the 

primary mitigation to deter and intercept illegal movement of live swine, people and 

vehicles. 

Another concern is that Chiapas only recently (late 2012) made the recommended 

changes to their CSF diagnostic protocol; therefore, there is some uncertainty to the 

laboratory results and epidemiological investigations conducted in 2011 and early 2012. 

SENASICA has recently made changes in the animal health leadership of Chiapas in an 

attempt to address the deficiencies in their CSF surveillance activities.

Incomplete epidemiological investigations of CSF suspect cases

During the last several years, SENASICA has improved the quality and consistency of 

field epidemiological techniques and standards. However, these improvements have not 

been uniformly implemented in all areas of the country. APHIS is concerned about

continued problems with the quality of some epidemiological investigations of CSF 

suspect cases. Specifically, APHIS is concerned about the thoroughness of the 

investigations and lack of trace-in and trace-out activities of some suspect cases. In some 

investigations staffs have not selected proper animals to sample or have not chosen the 

most appropriate diagnostic test to run on the samples collected. For example, several

cases involved swine in which high titers to CSF antibodies had previously been 

detected; these were selected for sampling to test for CSF antigen and/or virus isolation 

long after live virus, if it had been present, would likely have been cleared from the 

animal. In general, CSF antibodies are detectable 10 to 14 days post infection (dpi) at the 

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Evaluation of the CSF Status of a Region in Mexico October 2013

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earliest, while the ability to isolate virus from tonsil tissue begins declining 

simultaneously with the appearance of antibody [3-8].6 

This problem could limit SENASICA’s ability to confirm or exclude CSF virus activity 

in accordance with international standards. However, APHIS acknowledges the ongoing 

efforts of SENASICA to address this issue, as evidenced by its recent attempts to correct 

investigation deficiencies. 

Proximity to CSF viral activity in neighboring countries

The existence of common land borders with CSF-affected regions in the south presents a 

risk for re-introducing CSF into Mexico. This factor is substantially mitigated because 

Mexico prohibits the importation of swine, pork, and pork products from countries it 

considers CSF-affected, including Belize and Guatemala. However, swine, pork, or pork 

products could be moved illegally into Mexico. The legal movement of people, vehicles,

or equipment that may be contaminated with undetected CSF virus may also reintroduce

CSF into Mexico. 

Mitigations

Because of these risk factors, APHIS determined certain restrictions are necessary to 

mitigate the risk of release of CSF virus via fresh pork and pork products originating in 

and imported from a CSF-low-risk region in Mexico. These restrictions will require 

SENASICA to certify certain conditions on the farm of origin and at the slaughterhouse 

and processing plants. 

Therefore, APHIS proposes to: 

a) Allow importation of Mexican-origin pork and pork products from a CSF-lowrisk region in Mexico subject to specified conditions.

b) Restrict imports of pork and pork products originating in and imported from a 

CSF-low-risk region in Mexico into the United States by requiring pork be 

6 The clinical signs and outcomes of CSFV infections vary considerably depending on the strain of virus as 

well as host and environmental factors. In general, antibodies are detectable 10 to 14 days post infection 

(dpi) at the earliest. In pigs with chronic CSF, neutralizing antibodies are detectable at the end of the first 

month post infection but disappear a few days afterwards [3-6, 8]. 

Antigen detection is even more variable depending on the virus strain. For highly virulent CSFV strains 

(such as the Brescia strain), animals die within 9 to 14 dpi and virus is detected 2 to 4 dpi onwards. 

However, moderately virulent CSFV strains (like the Haiti strain) can be detected up to 28 dpi in tonsils 

using the PCR. Low virulent strains, like the Bavaro, have been detected in blood for up to 29 dpi, in 

tonsils scrapings for 21 dpi, and up to 70 dpi in histological sections of tonsil tissue [3, 6-8].

The times for virus detection in the same samples using the virus isolation (VI) test proved to be shorter. 

Some authors have explained this effect as the result of the formation of virus-antibody complexes. The VI 

test may start losing sensitivity simultaneously with the appearance of antibodies, around 14 dpi [6,7].

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Evaluation of the CSF Status of a Region in Mexico October 2013

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derived from swine raised on farms that operate under a high level of biosecurity 

and where CSF antigen exposure has not been detected. 

c) Require pork or pork products originating in and imported from a CSF-low-risk

region in Mexico be derived from swine not commingled with swine not

originating from herds operating under the required sanitary standards.

d) Require pork or pork products originating in and imported from a CSF-low-risk

region in Mexico not be commingled with pork or pork products derived from

swine not originating from herds not reared under the required level of sanitary

standards.

e) Apply restrictions described in 9 CFR 94.32 to pork and pork products originating

in and imported from a CSF-low-risk region in Mexico.

f) Require the establishment slaughtering swine to allow periodic on-site evaluation

and subsequent inspection of its facilities, records, and operations by an APHIS

representative.

APHIS proposes that SENASICA certify pork and pork products originating from a CSFlow-risk region in Mexico as derived from swine reared on premises meeting the 

following standards for sanitary conditions and biosecurity and not commingled with 

swine reared under less stringent standards: 

1. Herd is tested annually for CSF and the results show absence of antibodies to

CSF. The sampling protocol includes:

a. Serologic testing of the herd, using a testing protocol that allows

differentiation between CSF antibodies and cross-reactions with

antibodies to other pestiviruses. Sample size should be adequate to detect

5 percent prevalence at a 95 percent confidence level.

b. Samples from the herd may be collected at the slaughterhouse or the farm.

c. Any sick pigs showing clinical signs consistent with CSF are sampled and

tested for CSF antigen at any time. Any freshly dead pigs or pigs needing

to be euthanized are necropsied and complete diagnostics for CSF

performed.

2. Biosecurity measures include:

a. Containment of domestic pigs to prevent exposure to other swine, wildlife

or swine products.

b. Cleaning, disinfection, and control of movement of vehicles entering

farms or transporting swine.

c. Control of personnel entering the farm and keeping a written visitors’ log.

d. Training of personnel and farm veterinarians in awareness of risk of

fomite spread and clinical signs of CSF.

e. Recordkeeping of animal movements into and out of the farm (including

species other than swine).

f. Prohibition of swill feeding on the farm.

g. Documentation of adequate pest control on the farm.

h. Prohibition of farm personnel from owning or working with other swine or

in swine slaughter facilities.

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Evaluation of the CSF Status of a Region in Mexico October 2013

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3. Replacement stock and swine semen are sourced only from herds of equivalent

sanitary status not located in regions considered by APHIS to be CSF-affected or

are replacement stock or semen-donor boars that have tested negative for CSF

while being quarantined before introduction to the destination farm or semen

collection center.

4. Herds are not epidemiologically linked to CSF outbreaks and have not been

located within protection and surveillance zones established in response to CSF

outbreaks within the previous 12 months.

5. Herds are inspected annually by SENASICA, which verifies compliance with the

above conditions.

APHIS will also propose special restrictions requiring pork or pork products originating

in and imported from a CSF-low-risk region in Mexico to be derived from swine not 

commingled with swine originating from herds not meeting these sanitary standards. The 

proposed rule will also require pork or pork products originating from a CSF-low-risk 

region in Mexico for export to the United States to not commingle with pork or pork 

products derived from swine originating from herds not meeting the sanitary standards

described above. 

APHIS also intends to impose special restrictions described in 9 CFR 94.32. APHIS 

considers Mexico to meet the criteria described in this regulation because Mexico shares

a common land border with countries APHIS does not recognize as CSF-free. These 

restrictions prohibit the importation of pork and pork products derived from swine 

originating in or ever living in regions APHIS considers CSF-affected. Pork or pork 

products must derive from swine slaughtered at a federally-inspected establishment in a

region of Mexico from which pork or pork products are eligible for export to the United 

States. Further, the regulation prohibits the importation of pork or pork products that 

might have commingled with or be contaminated by pork or pork products derived from 

swine originating in CSF-affected regions.

APHIS concludes these mitigations will greatly reduce the likelihood that pork and pork 

products originating in and imported from a CSF-low-risk region in Mexico might be 

infected with or contaminated by CSF virus. 

Conclusion of Release Assessment 

APHIS identified risk factors associated with importing Mexican-origin pork and pork 

products into the United States from a CSF-low-risk region in Mexico and proposed 

mitigations to address these risk factors. APHIS concludes these mitigations will greatly 

reduce the likelihood that pork and pork products originating in and imported from a 

CSF-low-risk region in Mexico might be infected with or contaminated by CSF virus. 

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Section 5. Exposure Assessment

An exposure assessment as defined by the OIE describes the biological pathway(s) 

necessary for exposure of animals and humans in an importing country to the hazards 

released from a given risk source, and estimates the likelihood of the exposure(s) 

occurring [2]. APHIS' regulatory authority is limited to animal health, so potential risks 

to animals are the primary focus of this evaluation.

APHIS considers that the most likely pathway of exposure of domestic swine to CSF 

virus in pork and pork products is through feeding of contaminated food waste to swine

[66]. 

5.1. Waste Feeding to Susceptible Swine

The likelihood of exposure of susceptible species to virus-infected meat was evaluated in 

previous APHIS studies. In 1995, APHIS conducted a pathway analysis to estimate the 

likelihood of exposing swine to infected waste [67]. The analysis included two pathways 

for exposure of swine to contaminated waste; namely, exposure associated with illegal 

imports for personal use, and exposure associated with legal imports. The latter is the 

exposure pathway that would be applicable to importing pork or pork products from a 

CSF-low-risk region in Mexico. With 95% confidence, APHIS estimated that 0.023% or 

less of plate and manufacturing waste would be inadequately processed prior to feeding 

to swine [67]. Based on this fraction, less than 1 part in 4,300 (reciprocal of 0.023 

percent) of imported meat is likely to be fed to swine as inadequately cooked waste.

APHIS conducted a survey in 2001 of the U.S. swine waste-feeding sector to update a 

similar study done in 1994 [68]. Based on this survey, APHIS estimated that the 

proportion of plate and manufacturing waste fed to swine diminished by about 50% 

between 1994 and 2001 due to a decrease in the number of waste-feeding premises. The 

study also found that:

1. Several more U.S. States prohibited feeding food wastes to swine; 

2. The number of waste-feeding premises in the continental United States decreased 

by 40.5% from 1994-2001, and in Hawaii and Puerto Rico decreased by 37.5% 

and 52.3%, respectively; and 

3. Institutions and restaurants provide nearly 90% of all plate waste fed to swine. 

APHIS considers that prohibiting the feeding of unprocessed plate waste to swine has 

further contributed to the reduction of waste-feeding to swine. Waste-feeder operations 

must be licensed and inspected regularly by U.S. Department of Agriculture inspectors (9 

CFR §166). The licensing process requires that producers adequately cook the waste fed 

to swine using methods designed destroy foreign animal disease agents.

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5.2. Conclusion

APHIS assessed the likelihood of exposure of susceptible swine populations in the United 

States to CSF virus in fresh pork and pork products originating in and imported from a 

CSF-low-risk region in Mexico. Studies of the U.S. waste-feeding sector led APHIS to 

conclude susceptible swine in the United States are unlikely to be exposed to the CSF 

virus via waste feeding. 

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Section 6. Consequence Assessment

This consequence assessment, conducted in accordance with OIE guidelines, describes 

the consequences of introducing CSF into the United States [2]. The magnitude of the 

biologic and economic consequences following an introduction of CSF would depend on 

the location of the introduction; the virus serotype introduced; the rate of virus spread; the 

ability to detect the disease rapidly; livestock demographics and movement patterns; and 

the ease of control and eradication. Additionally, restrictions imposed by international 

trading partners may result in severe economic losses and other hardship to otherwise 

unaffected industry segments.

6.1. Effects on animal health and production

CSF is a highly contagious and frequently fatal viral disease of swine. Introduction into 

the United States would likely result in high rates of infection among exposed swine [72]. 

The severity and clinical presentation of CSF depends largely on the age of the animal 

and virulence of the viral strain, and can range from severe disease with up to 90% 

mortality to infections that are essentially asymptomatic. Young animals usually more 

severely affected than older animals. Low virulence strains may manifest primarily as 

poor reproductive performance and birth of piglets with neurologic defects [14, 72]. The 

effects on animal production parameters will vary based on the severity of disease; 

however, losses of animals, decreased growth efficiency, and reproductive losses could 

be expected in infected populations.

6.2. Control and eradication costs

Outbreaks of foreign animal diseases in previously free regions have historically been 

associated with large economic costs, including production and trade losses, as well as 

the costs of control and eradication. The overall costs of control and eradication depend 

magnitude of the outbreak and the control options utilized. For CSF-free countries like 

the United States that have a substantial export market for live swine, pork and pork 

products, the preferred option for control and eradication has traditionally been to stampout infected herds without the use of vaccine. 

Potential costs include disease control measures such as imposing quarantines and 

movement controls, direct costs related to stamping out of affected and contact herds, 

indemnity payments, surveillance and laboratory testing. The total cost of disease control 

and eradication, however, will depend on numerous factors, including the extent of 

spread and the prevalence of infection prior to detection, the density and types of 

populations of susceptible animals in affected regions, and which control and eradication 

strategies are ultimately implemented. Although the amount may be variable, it is likely 

that the cost of control, eradication, and compensation will be significant.

The most recent outbreak of CSF in the United States occurred in 1976. The costs of a 

CSF eradication program conducted from 1961 to 1976 was approximately $140 million 

at that time [73]. No recent data are available regarding costs of control and eradication in 

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the United States. For illustration, reported costs of CSF control and eradication in other 

countries are summarized below.

Saatkamp et al (2000) reviewed the economic aspects of control of small and large CSF 

outbreaks in the European Union (EU) from 1990 to 1997. For the largest outbreak, 

involving 429 herds over 14 months, the cost of removing affected swine was the 

equivalent of $401 million U.S. dollars, slaughter for welfare purposes cost $1.1 billion, 

and program operational costs were $126 million. Overall, the outbreak cost pig 

producers $669 million, the national government $217 million, and the EU $760 million 

[74]. Approximately 10 million pigs were destroyed during the outbreak, primarily for 

welfare reasons (being in overcrowded conditions, or being overweight for slaughter) 

[75]. The total cost of smaller outbreaks ranged from $10.2 million (8 affected herds 

over 2 months) to $196 million (113 affected herds over 10 months) [74]. In all of these 

cases, the slaughter of swine, either for welfare reasons or because of infection or high 

risk, accounted for the vast majority of the estimated costs. 

The potential for rapid escalation of costs related to an outbreak is high since CSF is 

highly contagious and likely to spread rapidly. In addition, some CSF virus infections 

may result in mild or absent clinical signs, and could potentially spread without detection 

for some time. Lack of sufficient data; the unpredictability of the clinical course and 

patterns of spread of infections; and the complexity of the factors involved in spread, 

control and eradication make reliable estimation of the potential costs of control and 

eradication of CSF in the United States difficult or impossible. Results of this qualitative 

assessment, however, suggest that the costs would be substantial. 

6.3. Market Impacts

In 2011 the value of production of hogs and pigs exceeded $20 billion, (NASS), and the 

value of pork exports exceeded $ 6 billion, (ERS). Potential market impacts of a CSF 

outbreak include export losses as a result of trade restrictions, reductions in consumer 

demand, falling retail prices for commodities, and potential alterations to industry 

structure due to market disruptions [74, 76]. The impact of a foreign animal disease 

outbreak on the viability of rural and regional economies, including businesses reliant on 

livestock revenue, could also be substantial. The extent of market impacts will depend on 

a number of factors, including outbreak size, the industry segments affected, the efficacy 

of control measures, and the reaction of trading partners. Regardless, CSF spreads 

rapidly, and its identification in previously free regions generally results in trade bans, so 

the market impacts of an outbreak are likely to be substantial.

Paarlberg et al. (2009) used an economic simulation model that captures vertical and 

horizontal linkages in the agricultural sector to estimate the effect that an outbreak of 

CSF would have on the swine industry in the United States. The duration and extent of 

the outbreak were extrapolated from the 1997-1998 Dutch CSF epidemic. Assumptions 

included destruction of 11 million hogs, closing of export markets with eventual full 

recovery, and a 1% decline in domestic demand for pork. The model evaluated two 

different scenarios affecting different sectors of the industry (breeding swine versus 

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market hogs) and the ultimate market impacts of each. Pork industry losses in returns 

were estimated at $4 billion over 20 quarters. Total losses for hogs, including the value 

of animals depopulated, was estimated at between $2.6 billion and $4.1 billion [76]. 

Garner et al (2001) estimated the potential economic impact of CSF introduction into two 

important swine producing regions in Australia. The model estimated a loss of gross 

income of 28-37% for the pig industry in the affected regions, and a 9-11% loss in gross 

income for the national pig industry [77].

In conclusion, the market impacts of a CSF outbreak will vary based on the extent of the 

outbreak and the reaction of domestic markets and trading partners. However, losses, 

particularly to export markets, are likely to be substantial.

6.4. Effects on public health

Although public health consequences are not issues under APHIS’ regulatory authority, 

the subject is briefly addressed in this assessment. Direct public health consequences are 

insubstantial because the occurrence of CSF infection in humans is quite rare. In fact, the 

number of cases reported is so small when compared with the number of persons exposed 

to these viruses that the World Health Organization does not consider CSF to be a 

zoonotic threat to humans [78].

A substantial foreign animal disease outbreak can result in severe psychosocial effects on 

farmers and farming communities. The impact of foreign animal diseases on mental 

health is best documented for foot and mouth disease, but would likely be similar 

following a large outbreak of any foreign animal disease. Effects such as grief over 

losing animals, feelings of isolation and loss of control, fear of new outbreaks, 

disruptions in community life, loss of trust in authority, short- and long-term financial 

stress, and symptoms of depression and post-traumatic stress disorder have been 

documented [79-82]. Animal health emergency responders may also experience stress 

reactions and distress as a result of participating in or witnessing the culling of animals or 

having to deal with distraught owners of the animals [83]. 

6.5. Effects on the environment

Environmental effects have been considered under all applicable environmental review 

laws in force in the United States. These are considered in a separate, but related, 

environmental assessment. The environmental assessment complies with the National 

Environmental Policy Act (NEPA) and implementing regulations [84].

6.6. Conclusions

The biological and economic consequences of introducing CSF virus into the United 

States could be substantial, although they would likely vary based on the extent of the 

outbreak at the time of detection, the virus serotype introduced, and movement and 

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demographics of affected swine. Additionally, restrictions imposed by international 

trading partners could cause severe economic losses to the U.S. livestock industry.

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Section 7. Risk Estimation

Risk estimation consists of integrating the results from the release assessment, exposure 

assessment, and consequence assessment to produce overall measures of risk associated 

with the hazards identified at the outset. Thus, risk estimation takes into account the 

whole risk pathway from hazard identification to the unwanted event [2].

APHIS identified risk factors associated with importing Mexican-origin pork and pork 

products into the United States from a CSF-low-risk region in Mexico and proposed 

mitigations to address these factors. APHIS considers that with mitigations this risk from 

the CSF-low-risk region in Mexico would be low. The CSF-low-risk region in Mexico 

recognized by APHIS includes all of Mexico except the 9-states currently recognized as 

CSF-free and the State of Chiapas for which APHIS considers the CSF risk to be 

unacceptable.

APHIS concludes from the exposure assessment susceptible swine in the United States 

are unlikely to be exposed to CSF virus via waste feeding. 

Conversely, APHIS concludes that the biological and economic consequences of a CSF

outbreak in the United States could be substantial, although they would likely vary based 

on the extent of the outbreak at the time of detection, the virus serotype introduced, and 

movement and demographics of affected swine. Control and eradication measures could 

be costly, and restrictions imposed by international trading partners could be expected to 

result cause severe economic losses to the U.S. livestock industry.

In summary, although the consequences of a CSF outbreak in the United States would be 

serious, based on the findings of the release and exposure assessments APHIS believes 

our proposed mitigations will significantly lower the risk of CSF-infected pork or pork 

products entering the United States from a CSF-low-risk region in Mexico and exposing 

U.S. swine to the disease.

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67
Appendices

Appendix 1: Certification of the Centro de Palo Alto Laboratory as CSF Diagnostic Reference 

Laboratory in Mexico, November 28- December 1, 2011.......................................................... A-2 

Appendix 2: SENASICA Organization Chart ......,,,.............................................................. A-8 

Appendix 3: Mexico CSF Case Definition...........,,,..............................................................A-10 

Appendix 4: Mexico CSF Site Visit Report: Field Investigations of CSF Suspect Farms in the 

State of Guanajuato, November 14-18, 2011...........,,,............................................................. A-18 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 1
Appendix 1: 

Certification of the 

Centro de Palo Alto Laboratory as 

CSF Diagnostic Reference 

Laboratory in Mexico, 

November 28- December 1, 2011

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 2
Site Visit Report: Certification of the Centro de Palo Alto Laboratory as CSF Diagnostic 

Reference Laboratory in Mexico 

November 28- December 1, 2011

 

I. Introduction

a. This report summarizes the findings identified by USDA-FADDL representatives

(Consuelo Carrillo and Fernando J Torres-Velez) during the audit of the Centro de Palo 

Alto (CPA) reference laboratory in Mexico City and the site visits of El Salto and 

Zaplotanejo regional laboratories. This audit and site visits were conducted in response 

to the agreed plan during the bilateral technical meeting in McAllen, Texas in August 

2011.

II. Objectives

a. Audit of Centro de Palo Alto (CPA) laboratory. The following criteria were taken into

consideration during the audit: 

i. Facilities

1. Adequacy of equipment to performed CSF diagnostic assays. 

2. Proper allocation and separation of space per diagnostic technique; 

serology, molecular (PCR), and virus isolation.

ii. Staffing

1. Suitable technical staff to perform assays. 

2. Suitable highly skilled/trained technical staff to evaluate and interpret 

results. 

iii. Quality control and assurance

1. Evidence of ongoing QC/QA program supported by internal and external 

(international) proficiency panels.

iv. Testing and accessions management

1. Performance of CSF screening and confirmatory assays.

2. Management (prioritization) of samples as: routine diagnostics, 

surveillance, and inconclusive (suspects).

3. Record keeping: traceability and consistency.

b. Re-testing of samples collected by USDA APHIS staff (Pyburn and Gauthier) during a 

previous field visit.

c. Visual inspection and case management discussion of the Itxahluaca seropositive sow 

(ID# 290) and her piglets (CENASA).

d. Re-evaluation of inconclusive cases [rRT PCR (+) / Conventional PCR (-)] from 

Guanajuato.

e. Visual inspection (not certification) of El Salto and Zaplotanejo regional laboratories 

and audit of records in Zaplotanejo (traceability & consistency). 

III. Logistics

a. Consuelo Carrillo and Fernando J Torres-Velez conducted the audit and site visits. 

During the week-long visit, Carrillo was based in the CPA laboratory where she audited 

electronic and hardcopy records, and the techniques of the diagnostic assays. In 

addition she oversaw the testing of samples previously collected by APHIS FADD staff 

(Pyburn and Gauthier). Torres-Velez supported Carrillo and traveled to El Salto and 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 3
Zaplotanejo regional laboratories to conduct visual inspections of the facilities and 

audits of records for traceability in Zaplotanejo (followed paper trail of inconclusive 

cases submitted to CPA). A closing meeting to discuss findings, corrective measures, and 

future support was held at CENASA laboratories and hosted by the director Dr. Joaquin 

Delgadillo. This laboratory also housed sow #290.

IV. Findings (per objectives as listed in section II) 

a. Audit

i. Facilities: adequate. 

ii. Staffing: adequate. 

iii. QA/QC: adequate.

iv. Testing (assays) and accessions management: 

1. Twelve cases were selected at random from CPA’s records (Table 1). 

These cases were submitted to CPA for confirmation from the regional 

laboratories where these were classified based on the clinical and 

epidemiological history as: routine diagnostic, surveillance, or priority 1. 

2. Three positive cases (inconclusive) at the Zaplotanejo regional laboratory 

were selected at random to assess traceability and consistency with

records in CPA’s database and record keeping logs (Table 1). No 

concerns with traceability and consistency of records were found. 

3. Technical findings and suggested corrective measure are broken down 

per assay and summarized in Table 2.

b. Samples collected by USDA-APHIS staff during a previous field visit were all negative.

c. The Itxahluaca seropositive sow (ID# 290) and 5 piglets are being housed in the 

CENASA biocontainment facility.

i. One out of the 5 piglets is a naïve sentinel.

ii. All these animals are being sampled (oral swabs, tonsil scrapings, and serum) 

and tested weekly (rRT-PCR and serology). 

1. rRT-PCR for all animals was negative

2. Serology: all are seropositive (except sentinel)

d. Re-evaluation of Guanajuato cases [original result: rRT PCR (+) / Conventional PCR (-)] 

i. Original locations (case ID): 

1. Ma. Elvira (19043 / 21801 / 25406)

2. Medina (19022 / 21800 / 25379)

ii. Upon further testing, the above mentioned cases still remain inconclusive: rRT 

PCR (+) / Conventional PCR (+) using a new set of primers targeting a different 

region of the genome. 

iii. These results are pending further analysis since the conventional PCR was a 

modified protocol (redesigned primers). These samples are pending shipment to 

Plum Island for further evaluation.

e. No irregularities were found during the visual inspection of El Salto and Zaplotanejo 

regional laboratories and audit of records (Zaplotanejo).

V. Closing Meeting at CENASA laboratory; December 2, 2011

a. During the closing meeting, Drs. Pedro Paz and Joaquin Delgadillo agreed to house the 

seropositive sow #290 and piglets for 65 days. Possible options to manage the case 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 4
after this time frame were discussed but nothing finalized due to the cost of extended 

housing. 

b. September 13, 2012 was established as a possible starting point for declaration of free 

status based on the findings of this audit.

c. FADDL offered the following support services:

i. Diagnostic assistance of any suspect/inconclusive case(s)

ii. Assistance in the production of reagents

1. Antisera

2. Tissues (in high viremic phase for IHC controls if test is added to their 

repertoire) 

iii. References/bibliographies (they have limited access to peer reviewed literature)

VI. Concluding Remarks:

a. CPA leadership and staff were extremely accessible and transparent during this 

process.

b. APHIS-FADDL recognizes the significant advances accomplished by CPA in CSF 

diagnosis in the time frame provided. Passing results in the international Hannover CSF 

proficiency panel is proof of this.

c. In addition to the corrective measures suggested in Table 2, we identified a 

communication gap between the field and the laboratory. The following 

recommendations were given to assist in bridging that gap: 

i. Involve the laboratory at the early stages of a field investigation: this will 

improve the communication between the FADD (field veterinarian) and the 

laboratory. 

ii. Switch mode from surveillance to Priority1: once a regional laboratory makes a 

suspect / presumed positive determination, the case should be managed as a 

priority 1 and no longer as a surveillance case. This will help to shorten the 

quarantine period.

d. FADDL is waiting for the import of inconclusive samples from Guanajuato. 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 5
TABLE 1. Cases selected at random for audit.

 Records Audited

Accessions (cases) audited 

in CPA

Accessions (cases) audited in 

Zaplotanejo 

26003 26038 22343

26002 25222 22168

25999 25128 20720

25994 25010-25350

25996 16789-24304

25975 25531

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 6
TABLE 2

Procedure / Diagnostic 

Technique

Finding(s) Suggested Corrective Measure Rationale

ELISA IDEXX This assay was only performed at 

regional laboratories. 

Repeat this assay at the CPA 

laboratory before performing 

confirmatory assays (IP and 

SNT). 

Validation of the ELISA IDEXX 

results performed at the regional 

laboratories is more time and cost 

effective than overwhelming CPA’s

SNT and IP test capacity.

Seroneutralization (SNT) Based on the Hannover proficiency 

panel results, CPA may be 

experiencing a slight decrease in 

sensitivity of the PK-15 cells 

currently used in this assay.

Change to or add another cell line 

to the assay, such as SK-6.

Weak positives may escape 

detection in PK-15 if these cells are 

not sensitive enough to infection.

rRT-PCR False positives: [rRT-PCR (Ct ≤ 40), 

conventional PCR and VI (-)] are not 

being further investigated, but 

recorded as negatives.

To rule out contamination, the 

original sample can be retested 

using fresh reagents. 

Alternatively, the amplified RNA 

can be sequenced.

Ct values equal or lower than 40 

MUST be reported as positive, even 

if the conventional nested PCR and 

VI are negatives. In this case of 

apparent false positive, a laboratory 

contamination must be ruled out 

first.

Inconclusives: [rRT-PCR (Ct = 41-

45), conventional PCR (-)] are not 

being further investigated, but 

recorded as negatives.

Run the sample RNA by rRT-PCR 

again and if the result still 

inconclusive a new RNA 

extraction must be perform and 

test by rRT-PCR and by VI.

Ct values 41-45 MUST be reported 

as inconclusives, even if the 

conventional nested PCR is (-), and 

followed up with a confirmatory test.

.

General comments:

• Retest suspect cases referred from regional laboratories before subjecting the samples to VI.

• Results of all assays performed to rule out the original result as a false positive or inconclusive must be 

included in the case record.

• Implementing these practices in molecular diagnostics crucial as it will provide the laboratory with 

valuable experience in the behavior of the assay’s reagents and conditions.

Conventional nested PCR 

(Sandvick technique)

Extremely faint bands in the gel. Develop a titration curve using 

various concentrations of the 

control RNA. Test these samples 

in parallel by rRT-PCR.

Faint bands make interpretation 

challenging and occasionally 

subjective. A titration curve will help 

to assess the sensitivity of the assay 

and how it compares to Ct values 

using rRT-PCR

Extraction control is not being used. Include actin as an extraction 

control. 

An extraction control assures that 

negative samples are not false 

negative (RNA was extracted from

tissues).

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 7
Appendix 2: 

SENASICA Organization Chart

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 8
DIRECCIÓN GENERAL DE SALUD ANIMAL

NOTA:El departamentode Regulación yRegistrosactualmenteestá registrada enla DirecciónGeneral deinocuidad,Agroalimentaria,Acuícola yPesquera

DIRECCIÓN

GENERAL DE

SALUD ANIMAL

KA1

DIRECCIÓN

DE VIGILANCIA

EPIDEMIOLÓGICA

MB1

DIRECCIÓN

DE CAMPAÑAS

ZOOSANITARIAS

MB1

SUBDIRECCIÓN

DE REGIONALIZACIÓN,

RASTREABILIDAD Y

ANÁLISIS DE RIESGO

NB1

DEPARTAMENTO

DE RASTREABILIDAD

OA1

DEPARTAMENTO

DE REGIONALIZACIÓN Y

ANÁLISIS DE RIESGO

OA1

SUBDIRECCIÓN

DEL SISTEMA NACIONAL

DE VIGILANCIA

EPIDEMIOLÓGICA

NB1

DEPARTAMENTO

DE REGISTRO, ANÁLISIS

Y DIFUSIÓN DE

INFORMACIÓN

OA1

SUBDIRECCIÓN

DE SANIDAD EN

ESPECIES MENORES

NB1

DEPARTAMENTO

DE SANIDAD

PORCINA

OB1

DEPARTAMENTO

DE SANIDAD

AVÍCOLA

OA1

SUBDIRECCIÓN

DE SANIDAD EN

ESPECIES MAYORES

NA1

DEPARTAMENTO

DE TUBERCULOSIS

BOVINA Y BRUCELOSIS

OA1

DEPARTAMENTO

DE RABIA PARALÍTICA

BOVINA Y GARRAPATA

OA1

DIRECCIÓN

DE IMPORTACIÓN,

EXPORTACIÓN, SERVIC

Y CERTIFICACIÓN PECU

SUBDIRECCIÓN

DE IMPORTACIONES

Y EXPORTACIONES

NB1

DEPARTAMENTO

DE IMPORTACIONES

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DEPARTAMENTO

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PROPUESTA DE REESTRUCTURACIÓNVIGENCIA: 1 DE ENERO DE 2008

GOBIERNO

FEDERAL

Evaluation of the CSF Status of a Region in Mexico - APPENDICES 

A - 9
Appendix 3: 

Mexico CSF Case Definition

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 10
SERVICIO NACIONAL DE SANIDAD, INOCUIDAD Y CALIDAD AGROALIMENTARIA

DIRECCIÓN GENERAL DE SALUD ANIMAL

No. DE OFICIO 800.02.01 /354 1613

SECRETARÍA DE AGRICULTURA,

4AISADERÍA, DESARROLLO RURAL,

PESCA y AllmJNTACIÓN SAGARPA

"2011, Año del Turismo en México"

México, D.F a 4 de abril de 2011

DR. JOHN R. CLIFFORD

DEPUTY ADMINISTRATOR DE APHIS/USDA

Hago referencia a los compromisos acordados entre el SENASICA y el APHIS/ USDA, a

fin de reevaluar la definición de caso de Fiebre Porcina Clásica (FPC), considerando las

observaciones realizadas por parte de ambas dependencias durante el "Curso-Taller

sobre investigación epidemiológica de fiebre porcina clásica México/Estados Unidos", que

se llevó a cabo del 19 al 21 de enero de 2011 en la ciudad de México. Con base en lo

anterior, se ha modificado y adecuado la definición de FPC quedando de la siguiente

manera:

DEFINICIÓN DE CASO DE FPC:

1. Caso Clínico.- El periodo de incubación del virus de FPC generalmente es de 7 a 10

días con un intervalo de 2 a 15 días. Bajo condiciones de campo el virus puede pasar

desapercibido hasta por 24 semanas después de la introducción a la piara. La

Organización Mundial de Sanidad Animal (01E) reconoce un periodo de incubación de

varios meses para cerdos expuestos in-útero, mientras que los cerdos expuestos después

del nacimiento tienen un periodo de incubación de 2 a 14 días.

Se considera como caso clínico a una piara con signología clínica compatible con FPC, en

la cual se observan cerdos con una viremia caracterizada por fiebre persistente igual o

mayor a 41°C; constipación; decoloración de la piel; hiperemia difusa; zonas de necrosis

en las orejas, en la cola y en los labios de la vulva; conjuntivitis y en algunos cerdos los

párpados con exudado purulento. Con frecuencia se observan signos nerviosos como

deambular en círculos, incoordinación, temblor muscular y convulsiones, aún en las fases

tempranas de la enfermedad; otros signos son abortos, vómito y/o diarrea que no

responden a tratamiento con antibióticos. La infección en cerdas preñadas puede producir

sólo una ligera hiperemia que va seguida de un incremento de abortos, carnadas

reducidas de tamaño, momificación, mortinatos y/o anomalías en las crías.

En cerdos infectados con cepas de baja y moderada patogenicidad, el diagnóstico clínico

es difícil, especialmente en cerdos viejos ya que generalmente estas infecciones se

manifiestan con casos leves o una infección subclínica que puede pasar desapercibida

or mucho tiempo, en estos casos el periodo de incubación es más largo que el normal y

...2

Av Cuauhtémoc No 1230 Piso Si Cu: unta Cruz Atoyac, Del. Benito Juárez_ México, D.F. CP 03310

Tel. 4 52 (55) 59 05 10 00 ext. 51055 y 51092

www senasica gob mx

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 11
SERVICIO NACIONAL DE SANIDAD, INOCUIDAD Y CALIDAD AGROALIMENTARIA

DIRECCIÓN GENERAL DE SALUD ANIMAL

No. DE OFICIO B00.02.01./354 1613

2 SECRETARÍA DE AGRICULTURA,

GANADERÍA, DESARROLLO RURAL,

PESCA V ALIMENTAC,ON SAGARPA

se pueden encontrar los siguientes signos: emaciación, alopecia, dermatitis, decoloración

de las orejas y una coloración púrpura de la piel en el abdomen.

Cabe mencionar, que la leucopenia es un hallazgo consistente en laboratorio (excepto

con cepas de baja virulencia) y la severidad de la enfermedad con cepas patógenas.

puede ser variable y manifestarse de tres formas distintas:

Aguda.- se presenta en lechones destetados menores de 12 semanas de edad que

no responden a un tratamiento con antibióticos, los cuales pueden presentar

signología caracterizada por fiebre (41°C), anorexia, letargia. hiperemia multifocal y

lesiones hemorrágicas de la piel, conjuntivitis, cianosis de la piel (especialmente en

las extremidades, orejas, miembros, cola y hocico), disnea, tos, estreñimiento

seguido por diarrea, vómitos (ocasionales), ataxia, debilidad de los miembros

posteriores, paresis, convulsiones, abortos (rara vez) y/o amontonamiento de los

cerdos. La muerte se produce de 5-15 días después del comienzo de la

enfermedad; la mortalidad de los cerdos jóvenes puede aproximarse al 100%.

En la fase aguda. el virus de la FPC ocasiona las siguientes lesiones: leucopenia.

trombocitopenia, hemorragias petequiales y equimosis con distribución difusa,

especialmente en la piel, nódulos linfáticos, laringe, vejiga y válvula ileocecal, así

como infarto multifocal del bazo (es característico pero no siempre se produce), es

común encontrar tumefacción de ganglios linfáticos y encefalomielitis con

infiltración linfocitaria perivascular.

Crónica.- los cerdos recuperados de una infección aguda, pueden desarrollar un

cuadro crónico caracterizado por una infección subaguda, seguida por una

convalecencia breve y una recaída con fiebre, anorexia, dermatitis, postración,

apetito irregular, pirexia, diarrea (puede durar hasta un mes) e incremento de

redrojos en la piara. La muerte ocurre de 1 a 3 meses después del cuadro inicial.

En esta fase, se pueden encontrar las siguientes lesiones: úlceras en forma de

botón en el ciego y el intestino grueso, así como depleción generalizada del tejido

linfoide.

c) Congénita- se presenta en lechones que nacen de madres infectadas después del

día 50 a 70 de la gestación, los cuales pueden estar infectados y no manifestar

signos clínicos por varios meses antes de morir, o pueden nacer con tremores

congénitos. Las hembras que se infectan antes del día 50-70 de gestación pueden

.3

Av. Cuauhtemoc No 1230 Piso 9 Col. Santa Cruz Atoyac. Del Benito Juarez México, D.F. CP 03310

Tel .+52 (55) 59 05 10 00 ext. 51055 y 51092

w" senasica.gob mx

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 12
SERVICIO NACIONAL DE SANIDAD, INOCUIDAD Y CALIDAD AGROALIMENTARIA

DIRECCIÓN GENERAL DE SALUD ANIMAL

No. DE OFICIO B00.02.01./354 1 6 1 3

- 3 -

SECRETARÍA DE AGRICULTURA,

GANADERÍA, DESARROLLO RURAL,

PISCA V AIIMENTACIÓN SAGARPA

abortar o tener lechones muertos, momificados o lechones vivos con defectos

congénitos o débiles. El único indicativo de una infección congénita por FPC,

puede ser la disminución de los índices reproductivos de la piara por abortos,

mortinatos o lechones débiles.

Las principales lesiones que se pueden encontrar son: dismielogenia central,

hipoplasia cerebelar, microencefalia, hipoplasia pulmonar, hidropesía y otras

malformaciones.

Es importante destacar, que también se pueden considerar como caso clínico

aquella piara con signología y lesiones compatibles con FPC en los que existe

evidencia de importación de material genético; o se utiliza escamocha como

alimento; o se identifica una relación epidemiológica de personas relacionadas con

la producción porcina en otro país.

Caso sospechoso de FPC.- Es aquel que corresponde a la definición de caso clínico;

o aquel caso con resultados positivos a ELISA, inmunoperoxidasa y virus

seroneutralización, sin información epidemiológica ni signos clínicos compatibles con la

enfermedad: o aquel caso en el cual el resultado del PCR convencional/ tiempo real no es

concluyente y/o la secuenciación del virus está pendiente en una muestra tomada durante

la vigilancia epidemiológica activa o pasiva.

Caso presuntivo positivo de FPC.- Corresponde a un caso sospechoso con resultado

positivo repetido a RT-PCR convencional/tiempo real o con secuenciación genómica

posterior a RT-PCR convencional de una muestra de cerdos con o sin signos clínicos y/o

evidencia epidemiológica de la enfermedad: o un cerdo o piara con información

epidemiológica y/o signologia clínica compatible con la enfermedad y RT-PCR

convencional/tiempo real positivo; o una prueba de inmunohistoquímica positiva; o una

prueba de seroneutralización positiva.

4. Caso confirmado de FPC.- es un porcino en el cual se aísla el virus de la FPC, con o

sin aparentes signos clínicos, lesiones compatibles y/o evidencia epidemiológica; y el

virus es confirmado por secuenciación en el laboratorio de la CPA.

TIPOS DE MUESTRAS Y TÉCNICAS DIAGNÓSTICAS PARA LA IDENTIFICACIÓN

DEL VIRUS DE FPC.- deberán obtenerse y enviarse en refrigeración a un laboratorio

oficial las siguientes muestras tomadas de cerdos clínicamente enfermos: tonsilas, hígado

...4

Av. Cuauhtémoc No 1230 Piso 9 Col Santa Cruz Atoyac. Dei Benito Juárez. México, D.F. CP 03310

Tel +52 (55) 59 05 10 00 ext. 51055 y 51092

www.senasica.gob.mx

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 13
SAGARPA

SENASICA

31RECCION GENERAL DE SALUD AMMAt

'94°3*4'4

SERVICIO NACIONAL DE SANIDAD, INOCUIDAD Y CALIDAD AGROALIMENTARIA

DIRECCIÓN GENERAL DE SALUD ANIMAL

No. DE OFICIO B00.02.01./354 1613

-4- SECRETARIA DE AGRICULTURA,

GANACIERIA, DESARROLLO RURAL,

PESCA Y ALIMENTACIÓN SAGARPA

riñón, nódulo linfático e íleon distal y las muestras de sangre completa conservada con

anticoagulante (heparina o EDTA).

Los métodos de diagnóstico que se desarrollarán en las muestras de tejidos serán:

inmunohistoquímica utilizando anticuerpos monoclonales específicos; PCR convencional y

tiempo real; aislamiento viral seguido de inmunohistoquímica y/o PCR convencional o

tiempo real y análisis de secuencia. En suero sanguíneo se realizará la detección de

anticuerpos para FPC por la técnica de ELISA la cual será confirmada por

inmunoperoxidasa y virus seroneutralización. corroborado con PCR, aislamiento viral y

secuenciación.

DIAGNÓSTICO DIFERENCIAL.- fiebre porcina africana: enfermedad de Aujeszky;

síndrome reproductivo y respiratorio porcino (PRRS), parvovirosis; circovirus porcino;

enfermedad de la frontera; síndrome de dermatitis y neuropatía porcina; síndrome

multisistémico de desgastamiento post-destete; diarrea viral bovina; púrpura

trombocitopénica, condiciones septicémicas por salmonelosis, erisipelosis, pasteurelosis,

actinobacilosis. hemofilosis por H. parasuis, estreptococosis: abortos por secuelas de la

enfermedad de Aujeszky, encefalomielocarditis o síndrome reproductivo y respiratorio

porcino (PRRS), así como algunas intoxicaciones y mortinatos.

EL DIRE TOR GENERAL 'l'II 

ATENTAMENTE ..11(.,54,43,A4Indejsk.

i Difti fYIRAL DE SALUD ANIMAL

1 Ur 1 4 AB 2011 (--

b L-------------i- -- 1 EznImi ffl rn,

, n OSO SANCHEZ - '

" '' .

OFICIALIA DE 

PARTESMVZ. HUG

Ccp MVZ. ENRIQUE SANCHEZ CRUZ.- Director en Jefe del SENASICA.

DR. CONRAD ESTRADA.- Veterinary Attaché de APHIS/ USDA.

DR. ASSAD HENEIDI ZECKUA.- Director de Epiderniologia y Análisis de Riesgo.

MVZ. IGOR ROMERO SOSA.- Director de la CPA.

Av Cuauhtémoc No 1230 Piso 9 Col Santa Ciuz Atoyac. Del Benito Juárez México. D.F. CP 03310

Tel. 4 52 (55) 59 05 10 00 ext. 51055 y 51092

wv.m.senasica gob mx

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 14
Courtesy Translation

Letter No. B00.02.01/354 1613 

Mexico City, Mexico, 4 April 2011 

DR. JOHN R. CLIFFORD

DEPUTY ADMINISTRATOR

APHIS/USDA

Reference is made to the commitments agreed between SENASICA and APHIS/USDA 

in order to evaluate the Classical Swine Fever (CSF) case definition, considering the 

comments made by both offices during the Mexico/US CSF Epidemiological 

Investigation Workshop held from 19 to 21 January 2011 in Mexico City. Based on the 

above, the CSF definition has been modified as follows: 

CSF CASE DEFINITION

1. Clinical Case – The CSF virus incubation period is generally 7-10 days with an 

interval of 2-15 days. On field conditions the virus could be unnoticed up to 24 weeks 

after its introduction to the herd. The World Organization for Animal Health (OIE) 

recognized an incubation period of several months for exposed pigs in-utero, while the 

pigs exposed after birth have an incubation period of 2-24 days. 

It is considered as a clinical case, a herd with clinical signs compatible to CSF, where 

pigs are observed with signs characterized by persistent fever equal or higher than 41o

C; 

constipation; decolorizing of the skin; diffused hyperemia; necrosis in ears, tail and the 

vulva lips; conjunctivitis and in some pigs the eyelids have purulent exudate. 

Neurological signs are frequently observed such as wandering in circles, lack of 

coordination, muscle tremors and convulsions, even in the early phases of the disease; 

other signs are abortion, vomit and/or diarrhea not responding to treatment with 

antibiotics. The infection in pregnant female pigs can cause a light hyperemia followed 

by the increasing of abortions, litters reduced in size, mummification, birth of dead pigs 

and/or other defects in the litters.

In pigs infected with low and moderate virulence strains, the clinical diagnosis is 

difficult, especially in old pigs, since these infections are shown as mild cases or a 

subclinical infection that can be unnoticed for a long time, in this cases the incubation 

period is longer and the following signs can be found: emaciation, alopecia, dermatitis, 

decolorizing of ears and purple coloring of the abdomen skin. 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 15
It is worth to mention that leucopenia is a consistent finding in laboratory (except with 

low virulence strains) and the severity of the disease with high virulence strains can vary 

and show in three different ways: 

a) Acute - Weaned suckling pigs less than 12-weeks old not responding to an antibiotic 

 treatment, which can present signs characterized by fever (41o

C), anorexia, lethargics, 

 multifocal hyperemia, and hemorrhagic lesions in the skin, conjunctivitis, cyanosis in the 

 skin (especially in the extremities, ears, penis, tail and mouth), dyspnea, cough, 

 constipation followed by diarrhea, vomit (occasionally), ataxia, weakness in rear legs, 

 paresis, convulsions, abortions (infrequently) and/or piling of the pigs. Dead happens 5-

 15 days after sickness started; mortality in young pigs can be near 100%. 

 In the acute phase, the CSF virus causes the following lesions: leucopenia, 

 thrombocytopenia, petechial hemorrhage and ecchymosis with diffuse distribution, 

 especially in the skin, lymphatic nodes, larynx, bladder and ileocaecal valve, as well as 

multifocal infarct to the spleen (it is characteristic but it does not always happen), it is 

 common to find swelling of lymphatic ganglia and encephalomyelitis with perivascular 

lymphocytic infiltration.

b) Chronic – The pigs recovered from an acute infection can develop a chronic chart 

 characterized by a subdued acute infection, followed by a short convalescence and a 

 relapse with fever, anorexia, dermatitis, prostration, irregular appetite, pyrexia, diarrhea 

 (lasting up to one month) and increasing of runts in the herd. Dead happens 1-3 months 

after the first chart.

 In this phase, the following lesions can be found: ulcers like buttons in the blind gut 

and the large intestine, as well as general depletion of the lymphatic tissue.

c) Congenital infection – pigs born from infected mothers after day 50 to 70 of 

 gestation, which can be infected without showing clinical signs for several months 

 before dying, or they are born with congenital tremors. The females infected before 

 the 50-70th day of gestation may abort or give birth to dead or mummified pigs, or 

live pigs with congenital defects or weak. The only indication of a congenital 

 infection by CSF could be the lowering of reproduction indexes in the herd due to 

 abortion, pigs born dead or weak. 

The main lesions that can be found are: central dismyelogenous, cerebellum 

 hypoplasia, microencephalia, lung hypoplasia, hydropsy and other malformations. 

 It is worth to mention that a clinical case can be also a herd with signs and lesions 

compatible to CSF where there is evidence of genetic material importation; or 

garbage is used for feeding; or it is identified an epidemiological relationship with 

 people related with swine production in other country. 

2. CSF Suspected Case – A case corresponding to the definition of clinical case; or such 

case with positive results to ELISA, immunoperoxidase and seroneutralization virus, 

without epidemiological information nor clinical signs compatible with the disease; o 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 16
such case where the results of conventional/rt-PCR are not conclusive and/or the virus 

sequencing is pending in a sample taken during active or passive epidemiological 

surveillance.

3. CSF Presumptive Positive Case – Corresponding with a suspected case with repeated 

positive results to conventional/real time RT-PCR or with genomic sequencing after a 

conventional RT-PCR of a swine sample with or without clinical signs and/or 

epidemiological evidence of the disease; or a pig or herd with epidemiological 

information and/or clinical signs compatible with the disease and positive 

conventional/real time RT-PCR; or a positive immunohistochemical test; or a positive 

seroneutralization test.

4. CSF Confirmed Case – A pig on which the CSF virus is isolated, with or without 

clinical signs, compatible lesions and/or epidemiological evidence; and the virus is 

confirmed by sequencing in the CPA laboratory. 

SAMPLE TYPES AND DIAGNOSIS TECHNIQUES FOR CSF VIRUS 

IDENTIFICATION – The following samples from clinically sick pigs must be taken 

and sent in refrigeration to an official laboratory: tonsils, liver, kidney, lymphatic nodes 

and distal ileum, and the whole blood samples must be preserved with anticoagulant 

(heparin or EDTA).

The diagnosis methods to be developed in the tissue samples will be: 

immunohistochemical using specific monoclonal antibodies; conventional and real time 

PCR; virus isolation followed by immonohistochemical and/or conventional or real time 

PCR and sequencing analysis. In the blood serum, antibodies detection for CSF will be 

carried out by ELISA, which will be confirmed by immunoperoxidase and virus 

seroneutralization, confirmed with PCR, virus isolation and sequencing. 

DIFFERENCIAL DIAGNOSIS – African swine fever; Aujeszky’s disease; porcine 

reproductive and respiratory syndrome (PRRS), parvovirus disease; porcine circovirus; 

border disease; porcine dermatitis and neuropathy syndrome; port-weaning weakness 

multisystemic syndrome; bovine viral diarrhea; thrombocytopenic purple; septicemic 

conditions for salmonellosis, erysipela, pasteurellosis, actinibacillosis, hemophillosis by 

H. parasuis, streptococcus, abortions due to Aujeszky’s disease, encephalomyelicarditis 

or porcine reproductive and respiratory syndrome (PRRS), as well as some intoxications 

and pigs born dead. 

SINCERELY,

THE GENERAL DIRECTOR

DR. HUGO FRAGOSO SANCHEZ

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 17
Appendix 4: 

Mexico CSF Site Visit Report:

Field Investigations of CSF Suspect Farms

in the State of Guanajuato,

November 14-18, 2011

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 18
Mexico CSF Site Visit Report

Field Investigations of CSF Suspect Farms in the State of 

Guanajuato

Monday, 14 Nov 2011 to Friday, 18 Nov 2011

Participants 

APHIS: Conrad Estrada and Marta Chavez (IS); Dave Pyburn and Julie Gauthier (VS)

SENASICA: Hugo Fragoso, Assad Heneide, Igor Romero, CPA staff

Guanajuato animal health Comité staff

Sheesley Enterprises: Dan Sheesley and Juan Carlos Valladares

Schedule

Mon, 14 Nov 2011 AM – D. Pyburn and J. Gauthier travel to Mexico City

PM – Meeting at Nikko Hotel with APHIS, SENASICA, and Sheesley Enterprises 

representatives to plan activities

Tues, 15 Nov 2011 AM- Travel to Irapuato, Guanajauto

PM – Meeting at Farmer’s Union to interview two producers individually: 

• J. Guadalupe Medina Martinez, owner of Medina Farm in Abasolo, 

Guanajuato

• Salvador Reyes Rodriguez, owner of Maria Elvira II in Penjamo, 

Guanajuato

Wed, 16 Nov 2011 • D. Pyburn and C. Estrada collect samples at Maria Elvira II farm, 

Penjamo

• M. Chavez and J. Gauthier collect samples at Medina farm, Abasolo

Thurs, 17 Nov 2011 AM – Travel from Guanajuato to Mexico City

PM – Debriefing at the Sheraton with APHIS, SENASICA, and Sheesley 

Enterprises representatives

Fri, 18 Nov 2011 D. Pyburn and J. Gauthier return to the U.S. from Mexico City

Medina farm, Abasolo, State of Guanajuato

Epidemiologic Investigation 

The Medina swine herd was tested as part of the CSF active surveillance program on 19 Sep 2011. Thirtyfive serum and seven whole blood samples were collected. The serum from one sow (#257) gave a 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 19
positive result on a CSF ELISA test performed at the CPA central laboratory. Confirmatory serologic test 

results were reported by CPA on 8 Oct 2011; the immunoperoxidase (IP) test result for serum from sow 

#257 was suspect and the seroneutralization (SN) test result was positive for CSF at a titer of 1:80. 

Due to the positive serologic test results, SENASICA issued a quarantine which was communicated with 

the owner on 13 Oct 2011. Resampling of the herd also took place on 13 Oct 2011; whole blood and 

serum was collected from 60 animals. Again, serum from sow #257 was positive by ELISA and suspect by 

IP. Another sow (#301) also tested positive by ELISA, but negative by IP. Negative virus isolation and CSF 

real-time polymerase chain reaction (PCR) test results were reported by CPA on 20 Oct 2011. However,

the real-time PCR test worksheets provided to APHIS by CPA show 25 positive test results for whole 

blood samples taken during the resampling on 13 Oct 2011. Results for the positive and negative 

controls run with the real-time PCR tests suggest that the tests were valid.

Medina farm, owned by Señor J. Guadalupe Medina Martinez, located in Abasolo, Guanajuato has 

existed for more than fifteen years. The farm raises swine from farrow to finish confined in a concrete 

building. The swine do not have access to the outdoors, and entry of people and animals is restricted by 

a solid gate and a high brick wall surrounding the premises. Manure is scraped from the solid concrete 

pen floors, carted to the street in a wheelbarrow, and loaded onto a vehicle to be carried and spread on 

local fields. Within the compound, the farm also has 14 cows for milk production, two sheep, and several 

caged pigeons. The producer’s home is within the farm compound. 

The producer reported his inventory of swine as 43 sows, 5 boars, 60 unweaned piglets, and approx. 150 

fattening pigs. All replacement gilts are born on the farm. Replacement boars are purchased at an 

auction in Abasolo, where boars are brought in from several areas of Mexico. Three boars were 

purchased in 2011, all from the Abasolo auction. Two boars purchased in September originated in 

Chiapas, and one boar purchased in January originated in Jalisco, according to the owner. 

He does not feed waste food to the pigs, other than whey byproduct from cheese-making using milk 

from his own cows. The swine diet is based on sorghum, which is grown locally. The nursery pigs are fed 

a commercial diet. 

Sr. Medina reported that he did not notice any illness in the swine this year, other than diarrhea in 15

day-old piglets last May, and one growing pig with bloody diarrhea a month ago. He believes that the 

diarrhea can be attributed to weather and diet change.

Sr. Medina employs one person to help on the farm. Visitors do not routinely enter the farm. The 

producer keeps a foot bath at the entrance to the barn and at the exit from the barn to his home. 

Fattening pigs are moved from the nursery area into the finishing area in groups of 20-25 pigs, and they 

remain in those groups until finished. A buyer comes to the farm with a truck to pick up finished pigs 

and deliver them to the municipal slaughter house. 

There are four other swine farms within 200-500m of Medina farm. Two farms were tested during active 

surveillance in May, apparently with negative results, and two farms were tested as part of the perifocal 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 20
investigation in September and October, which also were reported by SENASICA personnel to have 

negative ELISA test results. 

Sr. Medina suspects that a CSF seropositive sow (ear tag #257) might have been vaccinated for CSF at 

some time in her life, because she is an old sow, possibly 5-6 years old. However, both the producer and 

the CPA personnel reported that CSF vaccination ceased in that region in May, 2004.

Medina farm remains under quarantine pending test results on recent samples taken by CPA on 10 Nov, 

2011. The producer has approximately 20 finished hogs that need to be marketed at this time. 

The producer was reluctant for us to re-bleed animals that had been sampled only a week ago, so we 

discussed a plan of collecting tonsil scrapings and nasal swabs from younger animals (10-14 weeks old). 

The producer also agreed to allow us to sacrifice any ill pigs for necropsy. Guanajuato Comité 

representatives offered to purchase sick pigs for necropsy. 

On-farm investigation

Investigators: Iram Gonzalez (CPA), Jesus Arellano (Comité), Marta Chavez and Julie Gauthier (APHIS)

We arrived at the farm at approximately 10:00am. We established a ‘clean-dirty’ line at the farm gate, 

organized our equipment, and donned PPE. First, we walked through the entire facility to visually inspect 

the animals and map the premises. We did not observe clinical signs of illness suggestive of CSF, 

although there were several lame pigs of various ages, and many with dermatitis, possibly sarcoptic 

mange. Sow #257 was present and appeared healthy. One runt (‘redrojo’ in Spanish) – a thin, unthriftylooking growing pig - was separated from the rest of the herd. The producer offered this pig for 

euthanasia and necropsy. 

We sampled 25 pigs in the 10 to 14-week-old range from two different pens, taking tonsil scrapings and 

nasal swabs. The material from each tonsil scraping was placed in two separate conical tubes with a 

small amount (approximately 1 ml) of PBS. Both nasal cavities were swabbed, and each swab was place 

in a red top vial with a small amount (approximately 1⁄2 ml) of PBS. Each sampled pig was identified with 

an ear tag. The yellow ear tags were labeled with consecutive numbers 1-24. 

The runt was euthanized by electrocution and a necropsy was performed. The pig was small and thin for 

its age. No gross lesions were evident on necropsy. Lymph nodes were very small and difficult to locate. 

We collected serum and fresh tissues: tonsils; submandibular, axillary, gastrohepatic, and mesenteric 

lymph nodes; spleen; distal ileum; heart, lung, liver, and kidney. 

We cleaned and disinfected our equipment with Virkon® and removed our PPE at the farm gate. Trash 

was left with the producer, who said that he would burn it. Samples were bagged, the exterior of the bag 

was disinfected, and the box of samples was transported to a mobile lab provided by CENASA, which was 

parked near the Maria Elvira II farm in Penjamo.

In the ‘dirty’ room of the mobile lab, Marta Chavez and Julie Gauthier packaged the samples into two 

groups. Each set of samples consisted of tonsil scrapings, nasal swabs, and a set of fresh tissues. One set 

was labeled for CPA, and the other set was labeled “Save for Consuelo Carrillo” for her to use during the 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 21
CPA central lab visit planned for 28 Nov 2011. Sample sets were placed in the refrigerator of the mobile 

lab. Mobile lab personnel told us that they would drive the samples to the CPA central lab the following 

morning (17 Nov 2011). Conrad Estrada contacted Pedro Paz at the CPA central laboratory, and asked 

him to save the set of samples marked for Consuelo unopened in the refrigerator. 

Maria Elvira II farm, Penjamo, State of Guanajuato

Epidemiologic investigation

The Maria Elvira II swine herd was tested as part of the CSF active surveillance program on 19 Sep, 2011, 

the same date that the Medina herd was sampled. The serum from one sow (#619), out of 35 serum 

samples, gave a positive ELISA test result at the CPA central laboratory. Confirmatory serologic test 

results were reported by CPA on 1 Oct 2011; the IP test result for serum from sow #619 tested was 

suspect and the SN test result was positive for CSF at a titer of 1:40. 

Due to the positive serologic test results, SENASICA issued a quarantine which was communicated with 

the owner on 12 Oct 2011. Resampling of the herd took place on 13 Oct 2011, the same date that the 

Medina herd was resampled. Negative virus isolation and real-time PCR test results were reported by 

CPA on 25 Oct 2011. However, real-time PCR test worksheets provided to APHIS by CPA show six positive 

test results for whole blood samples taken during the resampling on 13 Oct 2011. Results for the positive 

and negative controls run with the real-time PCR tests suggest that the tests were valid.

The producer reported that the quarantine had been lifted recently and that he was currently sending 

finished pigs to slaughter.

Sow #619 was not resampled on 13 Oct 2011, because she had been sent to slaughter along with a 

pseudorabies reactor sow. The producer stated that sow #619 had been sent to slaughter because of her 

advanced age, although he admitted that the sow had always produced two healthy litters per year. 

Maria Elvira II farm, owned by Señor Salvador Reyes Rogriguez, located in Penjamo, Guanajuato, has 

existed for approximately 30 years. The owner’s home is located on the farm premises. The farm raises 

swine from farrow to finish in confinement. The swine do not have access to the outdoors, and entry of 

people and animals is restricted by a perimeter fence and gate. A bath and sprayer disinfects vehicles 

entering and departing the farm at the access gate. The producer reported his inventory of swine as 170-

175 sows, 3-4 boars, 120 unweaned piglets, and 780 fattening pigs. The herd was closed to introduction 

of new animals approximately five years ago. All replacement gilts are born on the farm. Semen provided 

by the local swine producer’s association is used for artificial insemination.

Sr. Reyes employs four people to help on the farm, who change clothes at the farm entrance prior to 

going to work with the swine. One employee is dedicated to tending the sow herd and another is a 

dedicated mechanic. The pigs do not receive waste food. The swine diet is based on sorghum, of which 

40% was grown by the farm owner and 60% was purchased this year. Feed is stored on the farm. A 

commercial premix is mixed with the sorghum. 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 22
Sr. Reyes reported that blue eye disease occurred in the herd this year. Routine veterinary care of the 

herd includes pseudorabies and blue eye disease vaccination, and deworming.

Visitors do not routinely enter the farm. Fattening pigs are moved from the nursery area into the feeding

area in groups of approximately 30 pigs, and they remain in those groups until finished. One buyer 

comes to the farm with a truck to pick up finished pigs and deliver them to a federally inspected 

slaughterhouse (TIF plant #137). 

No additional surveillance (perifocal sampling) was conducted as a result of the investigation of the 

Maria Elvira II farm. Sr. Reyes’ brother manages another pig farm co-located on the same family-owned 

10 hectare property as the Maria Elvira II farm. 

Sr. Reyes suspects that the CSF seropositive sow (ear tag #619) might have been vaccinated for CSF at 

some time in her life, because she is an old sow, possibly 5-6 years old. Both the producer and the CPA 

personnel reported that CSF vaccination ceased in that region in May, 2004, however.

The producer agreed to a plan for the APHIS team to conduct an on-farm investigation, collecting tonsil 

scrapings, nasal swabs, whole blood, and serum from growing pigs and from the six sows that tested 

positive by real-time PCR positive in Oct 2011. The producer also agreed to allow us to sacrifice any ill 

pigs, if present, for necropsy. Guanajuato Comité representatives offered to purchase sick pigs for 

necropsy. 

On-farm investigation

Investigators: David Pyburn and Conrad Estrada (APHIS), Juan Carlos Valladares (Sheesley Enterprises), 

Jose Luis Tafoya.

We arrived at the farm at approximately 12:00pm. Due to the farm being located on a busy highway with 

little room to park on the shoulder of the road, the producer insisted that we park our vehicles inside the 

farm gate. Our vehicles were disinfected by a gate dip and spray station as we drove on to the property. 

Once inside the property, we established a ‘clean-dirty’ line inside the farm gate, organized our 

equipment, and donned PPE. First, we walked through the entire facility to visually inspect the animals. 

We did not observe clinical signs of illness suggestive of CSF. Overall the pigs looked healthy and we did 

not see signs of disease other than an occasional cough in some of the pigs.

Blood was collected from sixty pigs for serum and whole blood testing. Two sows which tested positive 

by real-time PCR in Oct 2011 were available for resampling. In addition to serum and whole blood 

collection, nasal swabs and tonsil scrapings were also collected from these two sows. Nasal swabs and 

tonsil scrapings were also collected randomly from twenty-eight of the sixty sampled pigs. The material 

from each tonsil scraping was placed in a Whirl-Pak bag with a small amount (approx. 4 ml) of PBS. Both 

nasal cavities were swabbed, and each swab was place in a red top vial with a small amount (approx. 1 

ml) of PBS. Each sampled pig was identified with an ear tag. Pigs were chosen for sampling at random

from all pens that contained 10 to 14-week-old swine and from some pens with slightly older swine not 

yet ready for marketing. This sampling plan was designed to provide the best chance at finding CSF virus 

in the herd (10-14 week old pigs are more likely than other age groups to be shedding CSF virus in an 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 23
infected herd) and to allow tracing of individual pig in the event test results warranted further 

investigation.

We cleaned and disinfected our equipment with Virkon® and removed our PPE at the farm gate. Trash 

was left with the producer, who said that he would burn it. Our vehicles were disinfected at the farm 

gate as we left the farm. Samples were transported to a mobile lab provided by CENASA, which was 

parked near the Maria Elvira II farm in Penjamo.

In the ‘dirty’ room of the mobile lab, Marta Chavez and Julie Gauthier packaged the samples into two 

groups. Each set of samples consisted of tonsil scrapings, nasal swabs, whole blood, and serum samples. 

One set was labeled for CPA, and the other set was labeled “Save for Consuelo Carrillo” for Dr. Carrillo to 

use during the CPA central lab visit planned for 28 Nov 2011. Sample sets were placed in the refrigerator 

of the mobile lab with the packaged samples from the Medina farm, to be transported to the CPA central 

lab for analysis on the following morning (17 Nov 2011). 

Observations

The field team appreciated the invitation to work with CPA, State animal health Comité personnel, and 

the producers, especially on short notice. Producers, CPA, and Comité personnel were very helpful and 

pleasant to work with. Despite our many questions and unfamiliarity with their procedures, the 

producers and field investigators were very patient and cooperative. 

Field investigators acted in a professional manner and they were very conscientious about biosecurity. It 

was evident that the field investigators have the skills to observe the necessary biosecurity protocols and 

take appropriate samples. 

We found it very helpful to have the mobile lab available on-site to process our samples. The mobile lab 

personnel were extremely helpful and worked late hours to complete the sample processing. We hope 

that this excellent resource is used frequently in Mexico. 

Recommendations

1. Field personnel were unaware of the positive real-time PCR test results for the 13 Oct 2011 

samples from both Medina (25 positives) and Maria Elvira II (6 positives). Field personnel were 

given only the final report at a later date, which stated that real-time PCR test results for all 

samples were negative. We asked SENASICA staff for an explanation for the final negative 

interpretation of the positive real-time PCR results on the worksheet, but we were not given an 

explanation.

Communication between the laboratory and field personnel should be improved. Even 

preliminary test results are helpful for field investigators, in order to plan resampling, form 

epidemiological theories, and keep the owner informed and engaged productively in the 

investigation. The laboratory can advise the field personnel about the most appropriate types of 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 24
samples and methods of collection and preservation, in order to increase the probability that 

the virus, if present, will be found. 

2. Field personnel typically sample the sow herd only during investigations; they are not 

accustomed to sampling younger animals. Sampling should focus on the animals and samples 

most likely to harbor virus, if the objective is to find virus, or focus on animals likely to have 

antibodies, if the objective is to find antibodies. Take the right sample from the right animal at 

the right time. 

When hunting for CSF virus, the animals on which investigators should focus include: 

a. Young pigs about 10-14 weeks old

b. Sick pigs

c. ‘Poor –doers’, runts, slow-growing animals (redrojos)

The best samples for finding virus include:

d. Tonsil scrapings

e. Fresh tissues: tonsil, spleen, distal ileum, lymph nodes

When hunting for CSF antibody, investigators should focus on collecting serum from: 

f. Adult animals – sows and boars

g. Slow-growing finishers

3. Resampling of farms with positive test results from active surveillance should be prompt and 

handled as a high priority. The investigation is most urgent when CSF compatible clinical signs or 

epidemiological links to suspect farms are known.

4. Investigators should take a minimum of equipment on to the farm. Non-durable equipment 

(items that can’t be immersed in disinfectant) or disposable materials should be disposed of 

upon leaving the farm. During our visit, investigators took an excess quantity of supplies on to 

the farm and then took left-over supplies (conical tubes, syringes, media, blood tubes, etc.) off 

the farm to be used again. This puts other farms at risk of introduction of disease if these items 

are used on another farm.

5. Investigators need supplies to remove samples from farms and maintain biosecurity. During our 

visit, investigators were planning to carry samples off the farm and transport them to the lab 

without placing them in secondary containers or disinfecting them. Lacking sealable biohazard 

bags or secondary sample containers, the APHIS team improvised with trash bags and 

disinfected the bagged samples with Virkon® before transporting them to the lab. Field 

investigators should be provided with secondary containers for transporting the samples in order

to avoid contamination of people and surfaces on the way to the laboratory.

6. Investigators were provided with cotton swabs for collecting samples for PCR testing. The use of 

cotton swabs to collect samples for PCR reduces the sensitivity of the test. Polyester swabs are 

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 25
recommended for collecting samples for PCR testing, and these should be provided to the 

investigator.

7. Investigators need smaller specula and appropriate spoons for collecting tonsil scrapings from 

younger animals. The equipment that was provided to them was too big to be useful for smaller, 

younger animals. 

8. Trace-back and trace-forward investigations should be conducted more promptly and

aggressively for suspect CSF cases. Tracing animal movements to and from suspect farms will 

help to promptly confirm a case and to contain spread. Tracing animal movements becomes 

more difficult as time passes.

Evaluation of the CSF Status of a Region in Mexico - APPENDICES October 2013 A - 26