U.S. DEPARTMENT OF AGRICULTURE 

Marketing and Regulatory Programs

Animal and Plant Health Inspection Service

Veterinary Services 

VS Guidance 12001.4 

1

Policy for the Investigation of Potential Foreign Animal Disease/Emerging 

Disease Incidents (FAD/EDI)

1. Purpose and Background 

 

This document provides Veterinary Services (VS) policy for field investigation and 

communication of a potential Foreign Animal Disease/Emerging Disease Incident 

(FAD/EDI). Specific communication and operational procedures are provided in the 

Foreign Animal Disease Investigation Manual.

This guidance document represents the Agency’s position on this topic and is intended 

solely as guidance. It does not have the force and effect of law, does not create or confer 

any rights for or on any person, and does not bind the U.S. Department of Agriculture 

(USDA) or the public. Language suggesting that this guidance is mandatory (e.g., “shall,” 

“must,” “required”, or “requirement”) should not be construed as binding unless the 

terms quote from a statutory or regulatory requirement. The information this document 

contains may be made available to the public. While this document provides guidance for 

users outside VS, VS employees may not deviate from the directions provided herein 

without appropriate justification and supervisory concurrence.

2. Document Status 

 

A. Review date: 01/15/2024.

B. This document replaces Veterinary Services Guidance 12001.3. 

 

3. Reason for Reissuance 

 

VS is reissuing this guidance to reflect changes in procedure and structure.

4. Authority and References 

 

A. Authorities (Code of Federal Regulations (CFR)):

• 7 CFR part 331

• 7 CFR 371.4

• 9 CFR part 53

• 9 CFR part 71

• 9 CFR part 82

• 9 CFR part 94
U.S. DEPARTMENT OF AGRICULTURE 

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Veterinary Services 

VS Guidance 12001.4 

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• 9 CFR part 121

• 9 CFR part 122

• 9 CFR part 161

• 49 CFR part 173

B. References: 

• VSG 12000.3, “Foreign Animal Disease Diagnostician Certification Requirements” 

• Foreign Animal Disease Investigation Manual

• Introduction to the FAD Preparedness and Response Plan

 

C. Definitions: 

1) FAD: A terrestrial animal disease or pest, or an aquatic animal disease or pest, not 

known to exist in the United States or its territories. A FAD may be a World 

Organisation for Animal Health (OIE) listed terrestrial or aquatic animal disease 

(www.oie.int); additionally, at any time, the Secretary of Agriculture, or his or her 

designee, may designate a disease or pest as a FAD. Occasionally, “FAD” may be 

used interchangeably with Transboundary Animal Disease (TAD). An emerging 

disease is defined the VS Emerging Animal Disease Preparedness and Response 

Plans. An EDI is any incident involving an emerging disease that requires field 

investigation. A FAD/EDI may involve livestock, poultry, other animals, or wildlife.

In the event of a FAD/EDI investigation involving wildlife, VS will work in close 

collaboration, communication, and coordination with State, Tribal, and Federal 

wildlife agencies with primary jurisdiction and subject matter expertise for 

wildlife.

2) Foreign Animal Disease Diagnostician (FADD): A Federal or State employed 

veterinarian who has successfully completed specialized FAD diagnostician 

training at the National Veterinary Services Laboratories (NVSL), as well as any 

other specialized training and continuing education as required and administered 

by VS, including requirements specified in VS Guidance Document 12000.3.

VS Professional People Training (PPT) maintains a national roster of currently 

available or active FADDs. VS District Directors or designees maintain District 

rosters of currently available and equipped FADDs. Area Veterinarians in Charge 

(AVIC) maintain a roster of currently available and equipped FADDs in the 

jurisdiction(s) for which they are responsible.

5. Audience 

VS employees, other affected Federal and State agencies, and affected members of the 

public.
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VS Guidance 12001.4 

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6. Guidance 

The FAD/EDI investigation period is defined as the time from when the AVIC or his or her 

designee, and the State animal health official (SAHO) or his or her designee, initiate a 

field investigation until the time a FAD/EDI is ruled out or confirmed by a FADD field 

investigation, official NVSL laboratory diagnostic testing or study results, or by official VS 

case definitions.

A. Objectives 

1) Provide a veterinary assessment that consists of the following:

a. Differential diagnosis.

b. Classification of investigation, which is necessary to rank and prioritize the 

differential diagnosis in terms of the magnitude of suspicion for a FAD, in 

relation to the magnitude of suspicion for an endemic disease or condition.

c. Designation of diagnostic sample priority, which is necessary to rank and 

prioritize the speed at which diagnostic samples are to be collected, 

transported, and tested; the FADD, AVIC, and SAHO must concur on the 

designation of diagnostic sample priority. The Diagnostic Services Section 

head at NVSL’s Foreign Animal Disease Diagnostic Laboratory (FADDL) may 

also be consulted for input on priority levels. 

2) Provide presumptive and confirmatory diagnostic testing results as rapidly as 

required by the designation of diagnostic sample priority to rule out or confirm a 

suspected FAD/EDI agent.

The FADD, as part of the required site visit or field investigation, will determine if 

diagnostic sample testing or studies are necessary to rule out or confirm the 

FAD/EDI. The AVIC and SAHO retain the right to request diagnostic sample 

collection during a FAD/EDI investigation. The AVIC and SAHO, along with the 

FADD, NVSL, and laboratory director of the State National Animal Health 

Laboratory Network (NAHLN) laboratory, determine a diagnostic sample 

submission plan that may include a duplicate set of samples being submitted to a 

NAHLN lab.

3) Ensure the appropriate veterinary medical countermeasures, regulatory actions, 

and communications are recommended and implemented during the 

investigation period, as necessary, to prevent and/or mitigate the dissemination 

of a FAD/EDI agent by interstate or international commerce of animals, animal 

products, meat, articles, or conveyances. Examples of interstate or international 

commerce include but are not limited to slaughter or harvest facilities; processing 

or packing facilities; auction markets; exhibitions or shows; and interstate or 
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Veterinary Services 

VS Guidance 12001.4 

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international import-export-facilities. The appropriate veterinary medical 

countermeasures, regulatory actions, and communications will depend on factors 

such as:

a. The epidemiology of the suspected FAD/EDI agent (such as a highly 

contagious disease). 

b. The clinical and epidemiological findings obtained during the investigation as 

they correspond to the case definition for the suspected FAD/EDI disease 

agent (before obtaining presumptive or confirmatory diagnostic testing 

results).

c. The State, Federal, territory, and Tribal jurisdictions and authorities as 

applied to the specific situation.

B. Critical Elements 

Critical elements of an investigation include but are not limited to: Interviewing 

persons for incident history; observing clinical signs; physically examining animals; 

collecting and analyzing epidemiological information; collecting diagnostic samples as 

necessary; performing necropsy studies as necessary; investigating trace backs and 

trace forwards of animals, animal products, meat, articles, or conveyances as 

necessary; recommending and establishing intrastate quarantine as necessary (under 

the SAHO’s authority); and recommending and establishing interstate quarantines 

during the investigation period as necessary (under the Secretary of Agriculture’s

authority).

Critical data and information collected during an investigation includes but is not 

limited to: The species affected, clinical signs, lesions observed, herd/flock morbidity 

and mortality rates, duration of illness, vaccination history, diagnostic test history, 

nutritional status, premises conditions, movement history, contact history, evidence 

or indication of pest or vector, and evidence or indication of zoonotic disease.

C. Classification of Investigations and Correlation to Designation of Diagnostic Sample 

Priority 

1) Classification of FAD/EDI investigations and definitions

Classification of investigation, one of the FAD/EDI investigation objectives, 

represents the degree of suspicion for a FAD/EDI in relation to the degree of 

suspicion for an endemic disease or condition. Table 1 presents the three options 

for classifying FAD/EDI investigations and their definitions.
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VS Guidance 12001.4 

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Table 1: Classification of FAD/EDI Investigations and Definitions

Classification of

Investigations

Definition

High Suspicion The veterinary medical and regulatory assessments 

conducted are consistent with a FAD/EDI and are 

generally inconsistent with an endemic 

disease/condition

Intermediate Suspicion The veterinary medical and regulatory assessments

conducted are consistent with a FAD/EDI but are 

also consistent with an endemic disease/condition

Low Suspicion The veterinary medical and regulatory assessments 

conducted are generally inconsistent with a 

FAD/EDI and are consistent with an endemic 

disease/condition

2) Diagnostic sample priority designations

There are four diagnostic sample designations used during a FAD/EDI 

investigation. Designations take into account the magnitude of suspicion for a 

foreign animal disease, as well as the investigation location and consequences 

related to the speed of the investigation. Designations determine the speed with 

which sample collection, transportation, and diagnostic study are completed.

a. Samples designated as Priority 1 are only used for investigations where there 

is a High Suspicion of a FAD/EDI. Complete sample collection, transportation, 

and diagnostic testing using rapid to extraordinarily rapid methods. NVSL and 

NAHLN personnel perform diagnostic testing and studies as rapidly as possible 

when samples arrive at the laboratory, including nights, weekends, and 

holidays. NVSL uses overtime as necessary to begin and complete diagnostic 

testing and studies.

NAHLN laboratories perform testing as requested. Payment of overtime to 

NAHLN laboratory personnel varies by State. Extraordinary collection and 

transportation methods are required when the Priority 1 investigation 

includes a highly contagious FAD/EDI in the differential diagnosis, or when 

animals, animal products, meat, articles, or conveyances are involved or 

engaged in interstate or international commerce. This includes but is not 

limited to animals, animal products, meat, articles, or conveyances currently 

held in slaughter or harvest facilities, processing or packing facilities, auction 
U.S. DEPARTMENT OF AGRICULTURE 

Marketing and Regulatory Programs

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Veterinary Services 

VS Guidance 12001.4 

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markets, exhibitions or shows, and interstate or international import-export 

facilities. The National Preparedness and Incident Coordination (NPIC) Center 

must be notified by telephone of High Suspicion classifications. NVSL must be 

notified as well by telephone of a Priority 1 submission.

b. Priority 2 sample designations are used for investigations where there is an 

Intermediate Suspicion of a FAD/EDI. Use rapid methods to collect, transport, 

and study diagnostic samples. NVSL and NAHLN personnel perform diagnostic 

testing and studies immediately if the samples arrive at the laboratory before 

the close of the workday. NVSL uses overtime to complete testing and studies. 

NAHLN laboratories perform testing as necessary. Payment of overtime to 

NAHLN laboratory personnel varies by State. Diagnostic samples arriving after 

the close of the workday will be examined first thing the following day. 

Diagnostic samples received Saturday will be tested or studied on Saturday 

only with prior notification and discussion with NVSL and NAHLN laboratory 

personnel. NPIC does not require telephone notification of Intermediate 

Suspicion classifications.

c. The Priority 3 designation is only used for investigations where there is a Low

Suspicion of a FAD/EDI. Investigations with this designation use routine 

methods of collection, transport, and diagnostic study. NVSL and NAHLN 

personnel perform diagnostic testing and studies in accession order as 

received. NVSL and NAHLN overtime services will not be used for Priority 3 

investigations. The Priority 3 designation is also used for routine surveillance 

samples. NPIC does not require telephone notification of Low Suspicion

classifications.

The Priority A designation is only used for Intermediate Suspicion of a FAD/EDI

classification or Low Suspicion of a FAD/EDI classification when animals, 

animal products, meat, articles, or conveyances in interstate or international 

commerce are involved and/or are potentially held, delayed, or quarantined 

pending the results of diagnostic testing or studies for a FAD. It is also used 

when other known or potential circumstances associated with the 

investigation indicate it is prudent to obtain diagnostic sample testing results 

as rapidly as possible. NPIC requires telephone notification of Priority A 

designations. Use rapid to extraordinary methods to collect, transport, and 

study diagnostic samples. NVSL and NAHLN personnel perform diagnostic 

testing and studies as rapidly as possible upon sample arrival at the 

laboratory, including nights, weekends, and holidays. NVSL uses overtime as 

necessary to begin and complete diagnostic testing and studies. NAHLN 

laboratories perform testing as necessary. Payment of overtime to NAHLN 

laboratory personnel varies by State. NVSL must be notified as well by 

telephone of a Priority A submission.
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VS Guidance 12001.4 

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d. Extraordinary transportation methods include using hand carried samples, 

couriers, counter-to-counter services, and contracted commercial services. 

Rapid transportation methods include express shipping services such as 

FedEx® priority overnight. Routine transportation methods include express 

shipping services such as FedEx® priority overnight (to ensure preservation of 

diagnostic sample quality).

Table 2 presents the three diagnostic sample priority designations and their 

associated use and relative speed of sample collection, transportation, and 

diagnostic study. 

Table 2: Diagnostic Sample Priority Designations, Correlation to Classification of 

Investigations, and Speed of Sample Collection, Transportation, and Diagnostic 

Study

Priority Investigation 

Classification

Speed of Sample Collection, 

Transportation, and Diagnostic Study

Speed and Type of 

Contact Needed 

Priority 1 High Suspicion Rapid to extraordinary methods Immediate notification of 

NPIC and NVSL by phone Priority A Intermediate or 

Low Suspicion

Rapid to extraordinary methods

Priority 2 Intermediate Suspicion Rapid methods Timely notification of NVSL 

by phone or email Priority 3 Low Suspicion Routine methods

The FADD, AVIC, and SAHO must concur on the classification of the investigation; 

designation of diagnostic sample priority (1, 2, 3, or A); and if a duplicate sample 

will be collected and sent to an approved NAHLN laboratory in addition to NVSL. If 

the FADD, AVIC, or SAHO have questions, concerns, or disagreements regarding 

the investigation classification or the designation of diagnostic sample priority,

the FADD, AVIC, and SAHOs must immediately hold a conference call with the 

District Office, NVSL Director, and NPIC staff to resolve the issue. The NPIC staff 

and the District Office will host and coordinate conference calls. FADDL may also 

be consulted.

D. Diagnostic Case Definitions 

For more information on diagnostics, please see the Foreign Animal Disease 

Investigation Manual.

The VS Deputy Administrator classifies and designates FAD/EDI diagnostic case 

definitions. Examples of case definitions include “presumptive” and “confirmed” 

FAD/EDI cases and vary by disease. Refer to the Animal Health Surveillance 

SharePoint Site for disease-specific case definitions.
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Veterinary Services 

VS Guidance 12001.4 

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E. National Veterinary Services Laboratories (NVSL) 

NVSL safeguards U.S. animal health and contributes to public health by ensuring its 

nationwide animal health diagnostic system provides timely and accurate laboratory 

support.

NVSL is the official reference laboratory for FAD/EDI diagnostic testing and study in 

the United States. NVSL must perform or officially confirm the results of all diagnostic 

testing and studies related to FAD/EDI investigations in the United States unless 

otherwise specified by the Animal and Plant Health Inspection Service (APHIS) 

Administrator, or as delegated to the VS Deputy Administrator.

NVSL has two (2) locations for FAD/EDI diagnostic testing: Ames, Iowa (NVSL Ames) 

and Plum Island, New York (NVSL FADDL). The transport and shipping of FAD/EDI 

diagnostic samples to NVSL Ames or NVSL FADDL by species or suspected disease is 

found in the Foreign Animal Disease Investigation Manual.

Additional information regarding NVSL can be found online.

F. National Animal Health Laboratory Network (NAHLN) 

The NAHLN, created in 2002, is a comprehensive, coordinated, and modernized 

network of Federal and State animal health laboratories and public agricultural 

institutions that addresses emergency biological and chemical threats to animal 

agriculture and the security of the food supply. The NAHLN enhances early detection 

of FAD agents and newly emerging diseases and improves response to animal health 

emergencies (including bioterrorist events) that threaten the nation’s food supply 

and public health.

VS trains, proficiency tests, and approves NAHLN laboratory personnel to test for 

multiple high-consequence FADs. With the approval of the SAHO and AVIC, FADDs 

can collect FAD samples in duplicate to send one to the local NAHLN laboratory and 

the other to NVSL.

A current roster of the NAHLN laboratories and the testing they are approved to 

perform can be found online.

G. Guidelines for Diagnostic Testing 

However diagnostic testing is completed, NVSL is the official confirmatory laboratory 

for FAD/EDI testing in the United States unless otherwise specified by the U.S. Chief 

Veterinary Officer (CVO) (in other words, the VS Deputy Administrator).

1) At the discretion of the FADD, AVIC, and SAHO in collaboration with NVSL and 

NAHLN laboratory directors, two sets of diagnostic samples may be obtained.
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a. Always send the first set of diagnostic samples to the NVSL laboratory (NVSL 

Ames or NVSL FADDL) determined in the diagnostic sample submission plan.

b. Send the second set of diagnostic samples to an approved NAHLN laboratory 

to provide preliminary FAD/EDI diagnostic information before NVSL receives 

the diagnostic samples.

c. If a second set of diagnostic samples cannot be collected, send the samples 

that can be collected to the appropriate NVSL laboratory, not the NAHLN 

laboratory.

2) If an emergency situation occurs and the appropriate NVSL laboratory cannot 

perform FAD/EDI diagnostic testing, you may send one set of diagnostic samples 

to the other NVSL laboratory, and obtain a second set of samples for testing at a 

NAHLN Laboratory; or send the samples to another international reference 

laboratory as determined in the diagnostic sample submission plan. International 

sample shipments will require additional coordination and permitting. 

3) If AVIC and/or SAHO decide to submit a second set of diagnostic samples to the 

NAHLN laboratory, they must instruct the FADD to follow the procedures for 

submitting a second set of diagnostic samples to the NAHLN laboratory. The AVIC, 

SAHO, and/or FADD notify the NAHLN Laboratory Director if there is a change in 

the NAHLN laboratory submission plan after the FADD performs the investigation.

If a FAD/EDI outbreak occurs, VS provides further guidance on diagnostic sample 

submissions to a NAHLN laboratory.

H. Packaging and Labeling 

Packaging and labeling of biological substances for shipment requires familiarity with 

and training in current rules and regulations, which frequently change. Shippers are 

responsible for proper packaging, marking, labeling, documentation, classification, 

and identification of each shipment. Failure to follow regulations can result in 

substantial financial penalties.

 

For more information, please refer to the “Packing and Labeling Submissions” page.

I. State-Federal-Tribal Communication and Cooperation 

The coordinated State-Federal-Tribal response to a potential FAD/EDI requires close 

communication and cooperation among all stakeholders and jurisdictions. The AVIC 

and the SAHO (or designee) must closely communicate and cooperate on all aspects 

of a FAD/EDI investigation from initiation to completion.

All FAD/EDI investigations must be initiated by the AVIC and/or the SAHO. All FAD/EDI 

investigations must be assigned by the AVIC and/or the SAHO to a FADD. The AVIC 
U.S. DEPARTMENT OF AGRICULTURE 

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VS Guidance 12001.4 

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and/or the SAHO must timely initiate the investigation of all credible reported or 

suspected FADs/EDIs, including assigning a FADD to complete a site visit or field 

investigation as a required part of the investigation.

The AVIC and/or SAHO assigns a FAD/EDI Case Coordinator to assist with investigation 

support, communications, and Emergency Management Response System (EMRS) 

data entry, as required by the location, scale, complexity, or urgency of the 

investigation.

J. Emergency Management Response System (EMRS) 

The EMRS “Routine FAD/EDI Reporting” is a web-enabled database that is the official 

USDA APHIS database to record all FAD/EDI investigations. The EMRS database 

automatically sends email notices to selected VS personnel when FAD/EDI 

investigations are initiated in EMRS. This capability enables the field office and NPIC 

to monitor potential national “clusters” of FAD/EDI investigations in real time.

The AVIC, or his or her designee, ensures the EMRS Referral Control Number is 

assigned and transmitted to the FADD and the SAHO. EMRS must be used for all 

FAD/EDI investigations.

EMRS is accessed through the internet and permits approved State, VS, and NAHLN 

laboratory personnel access to enter and view investigations from their State or 

territory. All entries are confidential. EMRS database access at the State or territory 

level is controlled and maintained by approval of the AVIC and the SAHO.

K. Requirements 

Produce situation reports, spot reports, diagnostic updates, and regulatory 

assessments as required by the urgency or complexity of the investigation, or at 

intervals requested by the Field Office, the VS Associate Deputy Administrator for 

Strategy and Policy (the VS unit to which NPIC belongs), and the VS Deputy 

Administrator.

Because of the rapid exchange of information required during FAD/EDI investigations, 

use communications such as phone calls, conference calls, email, and fax when 

required, in addition to the official EMRS database to record information.

7. Inquiries 

Please direct any questions regarding these procedures or instructions to the NPIC staff.

Main Office: NPIC, One Health Coordination Center, FiOps Logistics Center.

Please refer to the FAD Investigation Manual for contact numbers.

Normal Business Hours: Monday – Friday 8 a.m. to 4:30 p.m. Eastern Time,
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NPIC/National Veterinary Stockpile (NVS) 24/7 Emergency Answering Service.

Foreign Animal Disease Investigations or Emerging Disease Incidents NVS Activation:

1-800-940-6524.
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Veterinary Services 

VS Guidance 12001.4 

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Acronyms 

ADA Associate Deputy Administrator

APHIS Animal and Plant Health Inspection Service

AVIC Area Veterinarian in Charge

CFR Code of Federal Regulations

CVO Chief Veterinary Officer

EDI Emerging disease incident

EMRS Emergency Management Response System

FAD Foreign animal disease

FADD Foreign Animal Disease Diagnostician

FADDL Foreign Animal Disease Diagnostic Laboratory

FiOps Field Operations

NAHLN National Animal Health Laboratory Network

NPIC National Preparedness and Incident 

Coordination

NVS National Veterinary Stockpile

NVSL National Veterinary Services Laboratories

OIE World Organisation for Animal Health

SAHO State Animal Health Official

USDA United States Department of Agriculture

VS Veterinary Services