Biosecurity risk assessment :  
Guinea pigs (Cavia porcellus ) 
from Australia  
 
 
 
 
 
 
 
May 2014   This page is intentionally blank 
  
 
 
 
Ministry for Primary Industries  
Pastoral House  
25 The Terrace  
PO Box 2526  
Wellington 6011  
New Zealand  
 
Tel: 64 4 894 0100  
Fax: 64 4 894 0731  
 
 
 
Science and Risk Assessment  
Ministry for Primary Indus tries 
 
 
 
 
 
 
Biosecurity risk assessment : Guinea pigs (Cavia porcellus ) 
from Australia  
DRAFT  for Public Consultation  
 
 
 
March 2014  
 
 
 
Approved for Public Consultation  
 
 
 
 
 
Christine Reed  
Manager, Biosecurity Science & Risk Assessment  
Ministry for Primary Industries   This page is intentionally blank   
 i Contents  
Executive Summary  1 
1. Introduction  2 
2. Scope  2 
3. Commodity definition  2 
4. Risk assessment methodology  3 
5. Developing the preliminary hazard list  6 
6. Brucella spp. 22 
7. Coxiella burnetii  24 
8. Leptospira serovars  27 
9. Exotic Salmonella serovars and phage types  31 
10. Weed seeds  34 
  ii Contributors to this risk analysis  
 
Primary Authors  
 
Stephen Cobb  Manager, Biosecurity 
Science and Risk Assessment 
(Animals and Aquatic) Team  Ministry for Primary 
Industries, Wellington, New 
Zealand  
Bob Worthington  Risk Analys t 
 Ministry for Primary 
Industries,  Wellington, New 
Zealand  
Internal Peer Review  
 
Erik van Eyndhoven  Principal Adviser, 
Conservation  
 Ministry for Primary 
Industries,  Wellington, New 
Zealand  
Sally Aitken  Senior Adviser, Animal 
Impo rts Ministry for Primary 
Industries,  Wellington, New 
Zealand  
Lincoln Broad  Senior Adviser, Biosecurity 
Science and Risk Assessment 
(Animals and Aquatic) Team  Ministry for Primary 
Industries,  Wellington, New 
Zealand  
   
Howard Pharo  Group Manager , Import and 
Export Animals  Ministry for Primary 
Industries,  Wellington, New 
Zealand  
   
External Scientific Review  
 
John Harkness  Mississippi State University  United States of America  
 
John C Schofield  Director of Animal Welfare , 
University of Otago  
 Dunedin , New Zealand  
Kathy Parton  Massey University  Palmers ton North , New 
Zealand  
 
  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 1 Executive Sum mary  
This qualitative risk assessment  examines the biosecurity risks involved with the 
importation of guinea pigs from Australia. An extensive preliminary list of organisms 
associated with guinea pigs was compiled from several sources including a world authority 
on guinea pig diseases , standard text books , electronic data bases , and related MPI risk 
analyses . Organism s that met the following criteria were excluded  from further 
consideration :  
 Organisms that do not occur in Australia  
 Organisms that al ready occur in New Zealand  
 Organisms that a re non -contagious opportunistic pathogens  
 Organisms that a re non -pathogenic or of low pathogenicity causing trivial diseases  
that a re of no consequence .  
As a result of individual risk assessments, weed seeds were classified as  risks  in the 
commodity and risk management options suggested  include : 
 Careful inspection on the day of export to ensure the guinea pigs are free from 
contamina tion with weeds and weed seeds, combined with an owner’s declaration 
that they have been fed on a high quality diet not including weed seeds for the past 
3 days.  
 Quarantine for 3 days with access to only high quality hay (without seeds), fresh 
fruit and ve getables or processed pellets.  
 Housing in cages with wire mesh floors whilst in quarantine.  
 2 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  1.  Introduction  
The last importation of guinea pigs from Australia occurred in 2000 after which the Import 
Health Standard (IHS) for guinea pigs was withdrawn by M PI. In 2005 a request  was made 
on behalf of “many hundreds of Cavy (Guinea Pig) fanciers and their clubs throughout 
New Zealand ” to again allow the importation of guinea pigs.  A draft risk analysis was 
written by an independent consultant1 and submitted to  MPI. That document served as the 
basis for this risk analysis, which will be the technical basis supporting the development of  
a new Import Health Standard . 
2. Scope  
This qualitative risk assessment  is limited to the risks associated with infectious and 
parasitic disease -causing organisms. Other risk factors that may be of commercial 
importance to importers (e.g. genetic diseases) are not biosecurity risks and are not part of 
this risk analysis. Measures that may be required to manage these risks are the 
responsibility of importer s.  
3. Commodity d efinition  
The commodity is c linically healthy guinea pigs ( Cavia porcellus ) that were born and 
continuously resident in Australia . 
                                                
1 Ann Ramus, Science Technology Consultants , 6809 River Road Tampa , FL 3361 5 -2848 , USA , with peer 
review by Krista Krey, Heather O’Neill, Neil Christensen, and John Harkness   
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 3 4. Risk a ssessment  methodology  
The methodology used in document  follows the guidelines as  described in Import Risk 
Analysis: Animals and Animal Products2 and in the relevant section of the World 
Organisation for Animal Health (OIE)  Terrestrial Animal Health Code  2009, hereafter 
referred to as t he Code.   
The process used by MPI is summarised in Figure 1.  
Figure 1 The risk analysis process  
 
 
                                                
2 Import risk analysis projects whic h have commenced after 12 April 2006 follow guidelines described in 
Biosecurity New Zealand Risk Analysis Procedures – Verison 1 . See www.biosecurity.govt.nz/files/pests -
diseases/surveillance -review/risk -analysis -procedures.pdf . 4 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries   
4.1. PRELIMINARY HAZARD L IST 
Using authoritative text s, electronic data bases  and organisms identified as significant by 
appropriate experts,  an exten sive list of organisms known to infect guinea pigs i s 
assembled. Organisms of concern are identified by applying specific criteria  to identify and 
eliminate th ose that are clearly not hazards . Organisms of concern constitute the 
preliminary hazard list , and the or ganisms on that list are subjecte d to more detailed 
examination .  
4.2. HAZARD IDENTIFICATI ON 
Each organism in the preliminary hazard list is subjected to a hazard identification step that 
includes formal identification of the organism, evidence of whether it is an OIE listed 
disease, its New Zealand status, the epidemiology of the organism in the animal species 
included in the commodity definition, and releva nt characteristics of the disease it causes  
in susceptible species . The hazard identification section is concluded by an assessment of 
whether the organism is identified as  a hazard  in the commodity or not. All hazards are 
subjected to individual risk asse ssment s.  
4.3. RISK ASSESSMENT  
Risk assessment consists of:  
Entry assessment : The like lihood of a hazard being imported with the animal.  
Exposure assessment : The likelihood of animals or humans in New Zealand being exposed 
to the hazard.  
Consequence assessment : The consequences of entry, establishment o r spread of a hazard . 
Risk estimation:  An estimation of the risk posed by the hazard  based on the entry, exposure 
and consequence assessments. If the risk estimate is n on-negligible, then the hazard  is 
assessed t o be a risk and  risk management measures are justified.  
Not all of the above steps may be necessary in all risk assessments. The OIE methodology 
makes it clear that if the likelihood of entry is negligible for a certain hazard, then the risk 
estimate is au tomatically negligible and the remaining steps of the risk assessment need not 
be carried out. The same situation arises when the likelihood of entry is non -negligible but 
the exposure assessment concludes that the likelihood of exposure to susceptible spe cies in 
the importing country is negligible, or when both entry and exposure are non -negligible but 
the consequences of introduction are concluded to be negligible.  
4.4. RISK MANAGEMENT  
For each organism assessed to be a risk , a risk management step is carried out, which 
identifies the options available for managing the risk. Where the Code  lists 
recommendations for the management of a hazard, these are described alongside options of 
similar, lesser or greater stringency where available. In addition to the optio ns presented, 
unrestricted entry or prohibition may also be considered for all risks . Recommendations for  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 5 the appropriate sanitary measures to achieve the effective management of risks are not 
made in this document. These will be determined when an IHS is drafted.  
As obliged under Article 3.1 of the W orld Trade Organization  Agreement on the 
Application of Sanitary and Phytosanitary Measures (the WTO SPS Agreement), the 
measures adopted in IHSs will be based on international standards, guidelines and 
recomm endations where they exist, except as otherwise provided for under Article 3.3 
(where measures providing a higher level of protection than international standards can be 
applied if there is scientific justification, or if there is a level of protection tha t the member 
country considers is more appropriate following a risk assessment).  
4.5. RISK COMMUNICATION  
After an import risk analysis has been written, MPI analyses the options available and 
proposes draft measures for the effective management of identified r isks. These are then 
presented in a draft IHS that is released together with a risk management proposal that 
summarises the options analysis, the rationale for the proposed measures and a link to the 
draft risk analysis. The package of documents is release d for a six -week period of 
stakeholder consultation. Stakeholder submissions in relation to these documents are 
reviewed before a final IHS is issued.  
  
 
 
 
 6 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  5. Developing  the preliminary hazard l ist 
The first step in the risk analysis is the identification o f agents of concern and the collation 
of these agents into a preliminary hazard list of organisms that might be associated with 
guinea pigs .  
5.1. ORGANISMS ASSOCIATED  WITH GUINEA PIGS  
The starting point for the preliminary hazard list was an extensive list of organisms of 
guinea pigs supplied by Dr John Harkness, an international authority  on laboratory animal 
diseases.  Dr Harkness’ list is given below:   
5.1.1. Bacterial Infections  
Gram p ositive  
Streptococcus zooepidemicus  - Lancefield’s Group C, beta haemolysis , lymp hadenitis, 
other organs, uncommon, mastitis  
S. pneumonia e - capsular types 4 and 19, uncommon, fibrinopurulent pneumonia  
Staphylococcus aureus  - common, pododermatitis, exfoliative dermatitis, inapparent 
infections also, conjunctivitis  
Corynebacterium pyog enes - rare, septicaemia  
Clostridium perfringens , type A - typhlitis , rare  
C. perfringens , type E - rare, enterotoxemia in “germ free” animals  
C. piliforme  - Tyzzers disease, enteritis uncommon in young  
C. difficile  - enterotoxemia follows antibiotic admin istration but some spontaneous cases  
Listeria monocytogenes  single reference, 1955, related to rabbit case  
Gram n egative  
Coxiella burnetii – zoonotic organism, reported in almost all species of domestic animals  
Salmonella typhimurium  - zoonotic potential, rare to common, may be inapparent  
S. enteritidis  - common with poor management  
S. dublin  - caused fatalities one case  
S. linete  - rare 
S. bledgam  - rare 
S. moscow  - rare 
S. Amersfoort  - rare 
S. marashio  - rare 
S. glostrup  - rare 
S. poona  - rare 
S. weltevr eden  - rare  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 7 Yersinia pseudotuberculosis  - rare, often inapparent, lymphadenitis, ileitis and cecitis  
Bordetella bronchiseptica  - common respiratory pathogen, interspecies spread  
Klebsiella pneumonia e - rare, bronchopneumonia to septicemias, mastitis  
Pasteu rella multocida  - rare, conjunctivitis, septicemia, pneumonia  
Pseudomo nas aeruginosa  - rare, pulmonary botryomycosis (lungs)  
Leptospira icterohemorrhagi ae - rare, one case, 1973  
Lawsonia intracellularis  - uncommon duodenal hyperplasia following steroid 
administration, diarrhoea  in spontaneous Asian outbreak  
Streptobacillus moniliformis  - rare, from abscesses, pneumonia  
Brucella abortus  - rare, only three reports for Brucella  
B. melitensis  - rare 
B. suis  - rare 
Escherichia coli  - carriers develop colibacillo sis following administration of some 
antibiotics, mastitis, uncommon  
Selenomonas ruminantium  - motile bacterium with flagella, three reports, Brazil and North 
America, low pathogenicity  
Chlamydia  
Chlamydophila caviae  - common, causes conjunctivitis (GPIC),  young affected, 
intracytoplasmic inclusions  
Other  
Mycoplasma pulmonis  – from mice, rare, few isolations  
M. caviae  - rare, recovered from single group of guinea pigs 1971  
Mycobacterium bovis  – rare, 1958  
M. tuberculosis  - rare, one case, 1953  
5.1.2. Mycotic Infec tions  
Dermatophytes  
Trichophyton mentagrophytes  - common, skin lesions, often asymptomatic, public health 
concern  
Microsporum canis  - uncommon  
Systemic m ycoses  
Histoplasma capsulatum  - rare, reported Brazil 1967  
Cryptococcus neof ormans  - rare, perhaps one report (1923)  
Candida alb icans  - rare, reported 1948  
Enteric r esident  
Sphaeromonas communis  - normal gut flora  8 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  5.1.3. Parasitic Infestations  
Ectoparasites  
Mites  
Trixacarus caviae  - worldwide, dermatitis, pruritus  
Chirodiscoides caviae  - common, few signs of derma titis 
Demodex caviae  - rare 
Myocoptes musculinus  - rare, one reference (1960)  
Notoedres muris  - rare two reports, from rabbits  
Sarcoptes scabiei  - rare 
Lice 
Gliricola porcelli  - most common, asymptomatic or dermatitis  
Gyropus ovalus  - uncommon, some signs  
Trimenopon hispidium  - rare 
Endoparasites  
Protozoa  
Cryptosporidium wrairi  - small intestine, diarrh oea or no signs, common USA  
Eimeria caviae  - common worldwide, diarrhoea , large intestine  
Klossiella cobayae  (renal) - common Europe, USA, South American, Af rica 
Encephalitozoon cuniculi  - worldwide, uncommon in guinea pigs   
Toxoplasma gondii  - Americas and Europe, uncommon, public health concern  
Leucocytozoon caviae  - Malaysia, 1908  
Trypanosoma brucei  - Africa, 1932  
Trypanosoma omsi  - South America, rare  
Leishmania enrietti  - from farmed guinea pigs  
Sarcocystis caviae  - subclinical, rare  
Giardia duodenalis  - possible zoonotic risk, worldwide, rare enteritis  
Tritrichomonas caviae  - common worldwide  
Endolimax caviae  - uncommon, USA, Asia, Europe  
Entamoeba caviae  - common USA, Europe, South America  
Chilomitus caviae  - probably common, worldwide  
Chilomitus conexus  - rare occurrence  
Hexamastix caviae  - uncommon, worldwide  
Hexamastix robustus  - uncommon  
Monocercomonas caviae  - USA, Europe, Brazil, uncommon   
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 9 Monocercom onas pistillum  - rare in USA  
Monocercomonas minuta  - rare in USA  
Chilomastix intestinalis  - may be common worldwide  
Chilomastix wenrichi  - uncommon, reported only in USA  
Retortamonas caviae  - common worldwide  
Monocercomonoides caviae  - common, USA, Brazil,  Europe  
Monocercomonoides quadrifunilis  - USA occurrence  
Monocercomonoides wenrichi  - no details  
Monocercomonoides exilis  - USA occurrence  
Enteromonas caviae  - USA and Europe, rare  
Proteromonas brevifilia  - rare in Europe and USA  
Colpodella edax  - rare 
Caviomonas mobilis  - uncommon, subclinical , flagellate, USA  
Oikomonas termo  - free-living coprozoic, Russia, France  
Balantidium caviae  - worldwide, rare to common, usually no signs  
Cyathodinium spp . - Worldwide, colonic endosymbionts  
Cyathodinium piriforme  - Brazil  
Cyathodinium cunhai  - Brazil  
Cyathodinium chagasi  - wild guinea pigs only  
Kopperia intestinale  - no detail, cecum  
Protocaviella acuminate  - rare reports, cecum  
Enterophrya elongate  - rare in South America  
Helminths  
Baylisascaris procyonis  - few rep orts, neurologic signs  
Paraspidodera uncinata  - worldwide, common, benign  
Fasciola  spp. - South America, may be common worldwide  
Pelodera strongyloides  - single report, dermatitis  
5.1.4. Viral Infections  
DNA v iruses  
Adenovirus - may be common in young, respirator y tract, intranuclear inclusions  
Cytomegalovirus (Herpesvirus) - inapparent, salivary glands, common  
Guinea pig “Herpes -like” virus (GPHLV) - no disease, probably rare, kidney  
Guinea pig “X” virus (GPXV) - from leukocytes, uncertain prevalence  10 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  Guinea pig p ox-like virus (GPPLV) - one report in young, rare, fibrovascular proliferation  
RNA v iruses  
Parainfluenza 3 viruses (PI -3 and CAV PI -3) - seroconversion common, subclinical  
Pneumonia virus of mice - rare seroconversion, mouse exposure  
Sendai virus (PI -1) - seroconversion, mouse exposure  
Arenavirus (LCMV) - rare, public health concern, neurologic syndrome  
Coronavirus -like virus - rare, wasting disease, diarrhea  
Picornavirus (MEV strain GD VII) - rare seroconversion, mouse exposure  
Reovirus 3 - rare seroconver sion, mouse exposure  
Raccoon -variant rabies virus (Lyssavirus) - rare occurrence, one report  
Simian virus 5 - uncertain or rare seroconversion  
Retrovirus (C -type) - rare, leuk aemia association  
5.2. REFINING THE LIST OF  ORGANISMS  
As illustrated in Figure 1, the following criteria were applied to identify agents that are not 
hazards:  
 Disease agents that already occur in New Zealand.  
 Organisms that are environmental, opportunistic pathogens that do not cause 
contagious diseases.  
 Disease agents that do not occur in  Australia.  
 Agents that are of very low pathogenicity causing trivial infections or are not 
known to be pathogenic.  
5.2.1. Bacteria  
Bacteria not identified as hazards include:  
 Organisms commonly identified in New Zealand as evidenced by quarterly reports 
from di agnostic laboratories: Staphylococcus aureus, Arcanobacterium pyogenes 
(formerly  Corynebacterium pyogenes ), Listeria mon ocytogenes  Yersinia 
pseudotuberculosis, Klebsiella pneumoniae, Pseudomonas  aeruginosa, Lawsonia 
intracellularis , Escherichia coli .  
 Other organisms that oc cur in New Zealand : Streptococcus zooepidemicus (Julian 
1992) , Streptococcus pneumoni ae (Brett et al.  1999) , Clostridium piliforme  (Graham 
1998) , Clostridium difficile  (Briant et al.  2005) , Bordetella bronchiseptica  
(Anonymous 1979; Shrubb 1998) . Streptobacillus moniliformis  (Sakalkale et al.  2007) . 
 Various types of Clostrid ium perfringens  that are associated with a wide variety of 
syndromes  and occur universally.   
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 11  Mycoplasma pulmonis  occurs  commonly  in rats and mice (Davidson et al.  1994)  
and is assumed to be present in New Zealand . It is not generally a pathogen of 
guinea pigs.   
 Mycoplasma caviae  is specific for guinea pigs  and is usually considered to be non -
pathogenic (Hill 1971b) . When the organism suspended in complete Freund’s agent 
was injected accidentally into a human, it caused a mild local reaction that resolved 
spontaneously and elicited an antibody response (Hill 1971a) . Mycoplasma caviae  
has also been isolated from guinea pigs but is not known to cause disease in guinea 
pigs (Schoeb 2010) . 
 Mycobacterium bovis  does not occur in Australia and according to Harkness (2009) 
only one case of naturally occurring Mycobacterium tuberculosis  has been 
described in guinea pigs in 1953.  
 Selenomonas ruminantium  is a normal inhabitant of the ruminal flora of ruminants 
and is not considered to be a pathogen.  
 Chlamydophila caviae  causes conj unctivitis in guinea pigs. It has been stated that 
“Chlamydophila caviae  is markedly specific for guinea pigs, as attempts to infect 
mice, hamsters, rabbits and gerbils have been unsuccessful, except for one 
experimentally infected gerbil” (Everett et al.  1999) . It is a common and typically 
self-limiting subclinical infection.  If disease does occur, full recovery usually 
follows within 4 weeks. Treatment, if needed, (eyedrops) is widely available. Since 
the organism is probably universally distributed and is usually a self -limiting 
infection confined to guinea pig s, it is not a  hazard.  
5.2.2. Fungi  
Fungal disease agents, except the dermatophytes, are opportunistic pathogens that exist in 
the environment and infected animals are not contagious . The dermatophytes mentioned in 
Harkness’ lists are already present in New Zealand. Therefore,  mycotic agents are not a 
hazard .  
5.2.3. Viruses  
All viruses listed above are not hazards:  
 Guinea pig adenovirus is listed by the International Committee on Taxonomy of 
Viruses (ICTV) as a tentative species (Benko et al.  2005) . The virus has not been 
isolated but is demonstrated by the presence  of typical inclusion bodies (Benko et 
al. 2005; Missouri University College of Veterinary Medicine 2002) . The 
morbidity, mortality and transmis sibility are reported to be low  (Schoeb 2010) . 
Benko et al.  report that the natural host range of adenovirus types is confined to one 
species or to closely related  species (Benko et al.  2005) . The refore, it is concluded 
that the virus causes a trivial disease and is confined to guinea pigs and is not a 
hazard . 
 Cavid herpesvirus  1 and Cavid herpesvirus 3 are unassigned viruses in the 
Herpesviridae. Cavid herpesvirus 2  (Guinea pig cytomegalovirus) is  a species in the 
Genus Roseovirus (Davison et al.  2005) . Cytomegal ovirus infection is described as 
inapparent, and common and occurr ing in salivary glands  and common if not 
ubiquitous and causing rare disease (Schoeb 2010) . According to Davison et al.  12 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  (2005) “As a general rule, the natural host range of individual viruses is highly 
restricted  and most herpesviruses are tho ught to have evolved in association with a 
single host species”. Studies on the various herpes viruses of guinea pigs indicate 
that they cause the development of antibodies but do not indicate that they cause 
significant disease (Bia et al.  1979; Bia et al.  1980; Connelly et al. 1987; Hsiung et 
al. 1976; Lam and Hsiung 1973) . No evidence was found to indicate that cavid 
herpes viruses occur in other species.  
Hsuing and Schoeb consider cavid herpes -like virus to be a synonym for Cavid 
herpesvirus 2 (Hsiung et al.  1976; Schoeb 2010) . No evidence was found that the 
virus occurs in species other than guinea pigs or that it causes significant disease.  
Guinea pig X virus is considered to be a synonym of Cavid herpesvirus 3. It is not 
known to cause disease (Schoeb 2010) . No evidence was found that it infects 
species other than guninea pigs.  Since cavid herpes viruses  cause trivial diseases 
and are not known to infect other species the cavid herpes viruses are not hazards.  
 
 Guinea pig pox -like virus is not liste d by the International Committe e on 
Taxonomy of Viruses as a known or tentative species within the pox viruses. Only 
one repor t was found relating to pox -like virus particles identifie d by electron 
microscopy in the muscles of guinea pigs. The virus was not isolated or formally 
identified (Hampton et al.  1968) . Therefore, it is considered to be a rare curiosity 
finding and it is  not identified as a hazard . 
 Cavid parainfluenza virus 3  is a virus that has been isolated from he althy guinea 
pigs. Experimental ly infected guinea pigs did not show signs of infection but 
developed antibodies to the virus (Simmons et al.  2002) . The virus is not a 
significant pathogen and n o evidence was found that it infects species other than 
guinea pigs. Therefore, it is not a hazard .  
 Pneumonia virus of mice  (PVM)  commonly infects mice causing no disease or a 
mild disease of short duration, except in immunologically compromised animals 
(Cerberus 2003)  or after serial passage of the virus in mice (Horsfall and Hahn 
1940) . No references were found indicating that long -term carriers of virus occur. 
Experim ental infection of guinea pigs did not result in signs of infection (Horsfall 
and Hahn 1940) . Mild lesions of bronchopneumonia were found in only 2 of 35 
guinea pigs infected nasally with the virus. However, 25 of the animals were 
infected spontaneously with Bordetella bronchseptica  during the  course of the 
experiment (Griffith et al.  1997) . There is no evidence that guinea pigs are 
maintenance hosts or long term carriers of the virus. Therefore, the virus is 
considered to be a virus of mice and rats and not of concern in guinea pigs. In 
addition , John Schofield , Director of A nimal Welfare  at Otago University , states 
that “the mouse and rat serology we have done indicates a low prevalence of both 
PVM and Sendai – mostly these occur in  mice. We don’t routinely test guinea pigs  
for serology” (Schofield 2010) . Therefore, the virus is not a hazard . 
 Sendai virus  causes infection primarily in mice, but also in hamsters, rats and 
guinea pigs (Faisca and Desmecht 2007) . Since the disease is already present in 
New Zealand (Schofield 2010)  the virus is not a hazard . 
 Lymphocytic choriomeningitis virus. The virus occurs commonly in wild mice. It 
has been described as occurring virtually worldwide (Southern 1996) . Therefore, it  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 13 is probable that  the virus already occurs in New Zealand . Information from CDC 
states that “While it might be possible for other animals to become infected with 
the virus, documented infections in humans have occurred only after exposure to 
infected mice and hamsters. Hum an infections almost always occur from house 
mice and rarely occur from pet hamsters”. The virus is commonly transmitted by 
hamsters or hamster cell lines (Peters et al.  1996) . Harkness (2009) , states that the 
virus is rare in guinea pigs. Since the disease is ra re in guinea pigs, almost certainly 
occurs in mice in New Zealand and is usually transmitted from mice or hamsters to 
humans it is not a hazard . 
 Coronavirus -like virus parti cles were identified by electron  microscopy and  
associated with wasting disease and  diarrhoea in guinea pigs. However the virus 
was not isolated or formally identified (Jaax et al.  1990) . In another study virus 
particles were identified in normal guinea pigs (Marshall and Doultree 1 996). No 
other references were found to this virus occurring in guinea pigs. This limited 
information does not constitute grounds for considering the vi rus to be a hazard . 
 Mice are the natural hosts of  several strains of  picornaviruses that cause mouse 
encephalomyelitis (Jacoby et al.  2002 ) . The species name of the virus is Theiler’s 
encephalomyelitis virus  (Stanway et al.  2005) . Antibody to mouse 
encephalomyelitis virus has been described in guinea pigs and some circumstantial 
evidence suggested that an encephalomyelitis virus might occur in guinea pigs 
(Hansen et al.  1997) . However, there has been no definitive work to demonstrate 
such a virus . Therefore, t hese viruses are assessed to be viruses of mice and are not 
a hazard.  
 According to Harkness (2009)  antibodies to Reovirus 3 have been reported rarely in 
guinea pigs exposed to mice. However, the ICTV does not list any re oviruses of 
guinea pigs or mice. Therefore, the antibody is likely to have been caused by 
incidental contact with unidentified reoviruses. Reoviruses are not  a hazard . 
 One case of rabies has been described in a guinea pig which was bitten by a rabid 
racoon  (Wadsworth Centre 2003) . This is a one -off case and the likelihood that a 
guinea pig destined for export to New Zealand would be bi tten by a rabid animal is 
considered to be negligible.  
 Simian virus 5 infects dogs, monkeys and humans (Lamb et al.  2005) . Canine 
parainfluenza virus is considered to be closely related to or identical to Simian 
virus 5 (Chatziandreou et al.  2004; Ford 2006; Gre ene 2006) . Since it only causes 
uncertain or rare seroconversion in guinea pigs (Charles River L aboratories 1989)  
and is probably identical to canine parainfluenza virus that occurs in New Zealand 
(Hill 1999)  it is not a hazard . 
 Guinea pig type -C oncovirus is an endogenous retrovirus found in the DNA of 
guinea pigs (Davis and Nayak 1977) . It is therefore not an infectious virus in the 
normal sense and  is not a  hazard . 
5.2.4. Protozoal infections  
 Cryptosporidium wrairi  is a parasite isolated from guinea pigs. Infections in guinea 
pigs are frequent ly subclinical. It did not infect immunodeficient mice (Chrisp et al.  
1995)  or chi ckens, t urkeys, mice or rabbits  (Vetterling et al.  1971) . It is considered 14 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  to be a trivial specie s-specific  disease  (Missouri University College of Veterinary 
Medicine 2002 ). Since the parasite causes a mild or trivial disease and is specific to 
guinea pigs it is not a hazard . 
 Eimeria caviae  is usually non -pathogenic but may cause clinical signs and 
mortality (Taylor et al.  2007a) . Another author described the parasite as being 
moderately pathogenic (Harkness et al.  2002) . It has a worldwide distribution 
(Taylor et al.  2007a)  and therefore probably already occurs in New Zealand. No 
reference s were found to it infecting species other than guinea pigs . Therefore it is 
not a hazard.  
 Klossiella cobayae  is a parasite of guinea pigs that has a predilection for the kidney 
but may be found in other organs. Clinical signs and gross necropsy signs are 
absent except in heavy infections (Hoffman and Hanichen 1970; Stojanov and 
Cvetanov 1965; Vetterling and Manning 1976) . No references were found to the 
parasite occurring in species other than guinea pigs. It has a worldwide distribution 
(Taylor et al.  2007b)  and therefore it is likely that that the parasite already occurs in 
New Zealand. Since the parasite causes a mild or trivial disease and is specific to 
guinea pigs it is not a hazard . 
 Encephalitozoon cuniculi  is primarily a parasite of rabbits and rarely found in 
guinea pigs. The parasite is found in New Zealand (Anonymous 1980)  and it is not 
a hazard . 
 Toxoplasma gondii  is endemic in New Zealand and therefore not a hazard . 
 Guinea pigs are susceptible to African animal trypanosomes (The Centr e for Food 
Security and Public H ealth 2009)  and have frequently been used for experimental 
investigations, but no reference was fo und to natural infection in guinea pigs. In 
South America guinea pigs are frequently infected with Trypanosoma cruzi  
(Basombrio et al.  1987; Vazquez et al.  1999) . However, vec tors for African 
trypanosomes ( tsetse flies ) and Trypanosoma cruzi  (Triatomes, kissing bugs) are 
not present in New Zealand and  none  of the trypanosome species occur in 
Australia. Therefore, the organisms are not a hazard.  
 Leishmania enrietti  infest s guinea pigs naturally (Machado et al.  1994) . No 
reference was found to the parasite occurring in other species. In addition the 
vectors for Leishmania  spp. (phlebot omine sandflies) ar e not present in New 
Zealand . Therefore, the parasite is not a hazard.  
 Sarcocystis  spp. have a complex life -cycle requiring a carnivorous primary host 
that becomes infected by eating an infected secondary host. Importing an infected 
guinea pig would not introduce the parasite unless the guinea pig was eaten by a 
competent carnivorous host. The parasitic infection in guinea pigs is described as 
subclinical and ra re. T he likelihood that the parasite could complete a complex life -
cycle and become established in New Zealand is considered to be negligible.  
Therefore, the organism is not a hazard.  
 Giardia duodenalis  and Giarida inte stinalis  are synonyms (Taylor et al.  2007a) . It 
is a common pa rasite of man and animals and is endemic in New Zealand (Hunt et 
al. 2000) . Therefore , it is not a hazard .  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 15  Chilomitus caviae  and Chilomitus conexus  commonly occur s in the caecum of 
guinea pigs (Griffiths 1971) , but no evidence was found that they are pathogens or 
that they occur in other animals. Therefore, the se organisms are not a hazard . 
 Tritrich omonas ca viae is a parasite that is found in the kidneys of guinea pigs. It is 
generally considered to be non -pathogenic and it has a world -wide distribution 
(Taylor et al.  2007e) . Therefore, it is not a hazar d.  
 Hexamastix caviae  and Hexamastix robustus  occur in the caecum of guinea pigs 
(Griffiths 1971)  but no evidence was located that they occur in other species or that 
they are pathogens. Th erefore, they are not identified as hazards . 
 Monocercomonas caviae, Monocercomonas pistillum and Monocercomonas minuta  
are not pathogenic (Charles River Laboratories International 2009) . No evidence 
was located that indicates that the parasites occur in species other than guinea pigs. 
Therefore they are not hazards. 
 Chilomastix intestinalis  and Chilomastix wenrichi . Of the 29 speci es of this genus 
listed in the T ree of Life project the two species listed above are the only ones from 
guinea pigs (Tree of Life Web Project 2008a) . There is no evidence that they are 
pathogenic or occur in other an imals. T herefore , they are not hazards . 
 Retortamonas caviae  is the only species from guinea pigs amongst 27 species listed 
from this genus (Tree of Life Web Project 2008c) . No evidence was found that the 
organism is pathogenic or occurs in species other than guinea pigs. Therefore, it  is 
not a hazard . 
 Monocercomonoides  caviae , Monocercomonoides qua drifunilis , 
Monocercomonoides wenrichi  and Monocercoomonoides exilis . No evidence was 
found that any species of Monocercomonoides  spp. is pathogenic. Therefore, these 
organisms are not hazards.  
 Enteromonas caviae  is the only species in the genus that is fr om guinea pigs (Tree 
of Life Web Project 2008b) . There is nothing to suggest that it is a pathogen or 
occurs in species other than guinea pigs. Therefore, it is not a hazard.  
 Proteromonas brevifilia  has been described in guinea pigs (Griffiths 1971)  but no 
evidence was found that it is a pathogen.  Therefore, it is not a hazard.  
 Colpodella edax  is a carnivorous protozoa that has been isolated from fresh water 
(Leander and Keeling 2004) . No evidence was found to suggest that it is a 
pathogen. Therefore, it is not a hazard . 
 Caviomonas mobilis  has been isolated fro m mice (Brugerolle and Regnault 2001) . 
No evidence was found that it is a pathogen. Therefore it is not a hazard . 
 Oikomonas termo  is a free -living protozoan that utilises bacteria as its food source 
(Hardin 1944) . No evidence was located that suggests that the organisms is a 
pathogen, Therefore, it is not a hazard . 
 Balantidium caviae  may be the same organism as Balantidium coli  (Scott 2005)  or 
a specific parasite of guinea pigs. In either case it is n ot regarded as a primary 
pathogen (Harkness et al.  2002)  but m ay be an opportunistic pathogen. B. caviae  
has a world -wide distribution  and is not identified as a hazard . 16 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries   Cyathodinium spp. occur commonly in guinea pigs (Alves et al.  2007)  and are 
found world -wide. No reports were found indicating that they are pathogens. 
Therefore, they are not hazards.  
 No information was found in thr ee electronic databases and available books on  
Kopperia intestinale, Protocaviella acuminate and Enterophyra elongate . 
Therefore, these organisms are assumed to be trivial non -pathogenic organisms and 
are not hazards . 
5.2.5. Helminth infections  
 Baylisascaris proc yonis  is a parasite of raccoons and rarely of dogs. Accidental 
infections of aberrant hosts have been described in many species of animals 
including humans and guinea pigs. However, in aberrant hosts the parasitic larvae 
penetrate the gut and migrate in ti ssues where they become encysted. The effects on 
aberrant hosts depend on which tissues are infected , when the brain is affected 
serious disease and death may result (Sorvillo et al.  2002) . However, unless animal 
tissues containing encysted larvae are ingested by a raccoon the life -cycle of the 
parasite remains uncompleted. Guinea pigs are dead -end hosts and not important in 
the epidemiology. Therefore , B. procyonis  is not a hazard .  
 Fasciola hepatica  occurs endemically in New Zealand.  Fasciola gigantica  occurs 
in tropical areas but is not present in Australia (Molloy et al.  2005) . Therefore, 
these organisms are not a hazard .  
 Paraspidodera uncinata  is a common, non -pathogenic or mildly pathogenic 
parasite of guinea pigs that occurs world -wide (Taylor et al.  2007c) . It has not been 
described in New Zealand (McKenna 2009)  but is likely to be present. It is 
considered to be non -pathogenic or mildly parasitic and it is a specific parasite of 
guinea pigs. Therefore, it is not identified as a hazard . 
 Pelodora strongyloides  is a saprophytic organism  found in soil and decaying 
vegetable material .  The larvae occasionally invade  the sk in of humans  and animals 
causing dermatitis (Fitzgerald et al.  2008; Rashmir -Raven et al.  2000; Saari and 
Nikander 2006; Yeruham and Perl 2005) . Guinea pigs are rare accidental hosts of 
the larvae (Todd et al.  1982) . Therefore, it is not a hazard.  
5.2.6. Ectoparasites  
The mites Trixacarus caviae, Chirodiscoides caviae, Mycoptes musculinus, Notoedres 
muris and Sarcoptes scabie i have all been described in N ew Zealand  (Tenquist and 
Charleston 2001) . Demodex caviae  has not been described in New Zealand but is a rare, 
strictly species -specific parasite that usually causes subclinical infections except in 
immunodeficient guinea pigs (Schonfelder et al.  2010) .  The lice Gliricola porcelli , and 
Gyropus ovalus  have been described in New Zealand (Tenquist and Charleston 2001)  and 
Trimenopon hispidium  is a rare parasite that is easily overlooked (Taylor et al.  2007d) . 
Therefore none of the mites list ed by Harkness or found in other sources are hazards . 
  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 17 5.3. PRELIMINARY HAZARD L IST 
The exclusion of organisms in the previous section , and the addition of weed seeds in line 
with all imports of live animals, resulted in the following organisms being retained on the 
preliminary hazard list  and therefore requiring individual risk assessments.  
 Brucella  spp. 
 Coxiella burnetii  
 Exotic Leptospira  serovars  
 Exotic Salmonella  serovars  
 Weed seeds  
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 22 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  6. Brucella  spp. 
6.1.  HAZARD IDENTIFICATIO N 
6.1.1.  Aetiological agent  
Brucella abortus, Brucella melitensis and Brucella suis .  
6.1.2. OIE list  
Listed.  
6.1.3.  New Zealand status  
Listed on the unwanted organisms register as exotic unwanted organisms . 
6.1.4. Epidemiolog y 
B. abortus  is a pathogen of cattle. B. melitensis  is a pathogen of sheep and goats and B. suis 
is a pathogen of pigs. Each of the species mentioned can occasionally  infect other species 
of mammals including humans, in which serious disease may result  (Godfroid et al.  2004a , 
2004b , 2004c) . Infections in humans and several other hosts are non -contagious . 
Guinea pigs are susceptible to infection and have been widely used for experimental and  
diagnostic purposes. However, when experimentally infected guinea pigs were kept in 
cages next to non -infected guinea pigs, cross contamination was not observed.  Injection of 
cultured bacteria or infected material into guinea pigs results in septicaemia w ith lesions in 
local lymph nodes and enlarged spleens and high antibody titres, but the guinea pigs do not 
develop clinical disease.  
Natural infections in guinea pigs are rare and only a few cases have been reported 
(Harkness 2009 ). 
B. abortus  and B. melit ensis  do not occur in Australia (OIE 2008)  and B. suis occurs only 
in feral pigs in Queensland and in humans that have had contact with the m (Godfroid 
2002; Robson et al.  1993) . 
6.1.5. Hazard identifi cation  conclusion  
B. abortus  and B. melitensis  do not occur in Australia  so are not identified as  hazards in the 
commodity . B. suis occurs in only feral pigs in Queensland.   In addition infected guinea 
pigs are likely to be dead -end hosts and natural infec tions in guinea pigs are rare. The 
likelihood that guinea pigs that will be exported t o New Zealand would have contact with 
feral pigs in Queensland is considered to be negligible. Therefore, B. suis is not identified 
as a hazard  in the commodity.  
  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 23 Referen ces 
Godfroid J (2002) . Brucellosis in wildlife. Revue Scientifiique et Technique , 21(2), 277 -86. 
Godfroid J, Bosman PP, Herr S, Bishop GC (2004a).  Bovine brucellosis . In: Coetzer JAW, Tustin RC, 
(eds), Infectious Diseases of livestock, 3, Pp. 1510 -27, Oxford University Press, Oxford.  
Godfroid J, Garin -Bastuji B, Blasco JM, Thomson J, Thoen CO (2004b).  Brucella melitensis infection . 
In: Coetzer JAW, Tustin RC, (eds), Infectious Diseases of livestock, 3, Pp. 1535 -41, Oxford University 
Press, Oxford.  
Godfroid J, Thoen CO, Angus BD (2004c).  Brucella suis infection . In: Coetzer JAW, Tustin RC, (eds), 
Infectious Diseases of livestock, 3, Pp. 1542 -5, Oxford University Press, Oxford.  
OIE (2008) . World Animal Health Information Database (WAHID) In terface. http://www.oie.int/wahid -
prod/public.php?page=home , downloaded 27/1/2009.  
Robson JM, Harrison MW, Wood RN, Tilse MH, McKay AB, Brodribb TR (1993) . Brucellosis: re -
emergence and c hanging epidemiology in Queensland. Medical Journal of Australia , 159(3), 153 -8. 
 24 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  7.  Coxiella burnetii  
7.1. HAZARD IDENTIFICATIO N 
7.1.1. Aetiological agent  
Coxiella burnetii  
7.1.2. OIE List  
Listed.  
7.1.3. New Zealand status  
Notifiable unwanted organism (MAF 2008) . New Zealand is free from C. burnetii  
(Worth ington 2001) . 
7.1.4. Epidemiology  
Coxiella burnetii  probably infects all mammalian species, birds and many arthropods 
(Marin and Raoult 1999; Marrie et al.  1993) . In animals the infections are of minimal 
economic importance and rarely cause disease, but it is a zoonotic organism that 
sometimes causes serious disease in humans. Most human i nfections are asymptomatic or 
present as a mild flu -like disease, but acute or chronic infections sometimes occur , 
occasionally with serious complications such as myocarditis, endocarditis, hepatitis, and 
renal failure (Marin and Raoult 1999; Woldehiwet 2004) . Sporadic abortions occur in 
humans and animals  (Hatchette et al.  2003; Marin and Raoult 1999; Raoult et al.  2002; 
Woldehiwet 2004) . 
Transmission commonly occurs through  contact with inf ected uterine discharges and 
placentae and probably by inhalation of dust contaminated by birth products (Arricau -
Bouvery and Rodolakis 2005; Behymer and Riemann 1989; Hawker et al.  1998; Marin and 
Raoult 1999; Marrie et al.  1993; Selvaggi et al.  1996; Tissot -Dupont et al.  1999) . Infected 
ticks may also play a role in transmission; a t least 40 species of ticks from 11 genera can 
be infect ed (Kelly 2004)  and their dried faeces contaminates dust. 
Infected animals generally show no clinical signs,  thus making the determination of the 
incubation period and the interval to the development of antibodies difficult to determine. 
In humans the incubation period is given as 1 -3 weeks and the development of detectable 
antibody titres takes 2 -3 weeks after the onset of symptoms (Marin and Raoult 1999) . 
It is assumed that infected guinea pigs will develop antibodies  within a simi lar time 
interval after infection . 
Wild rodents may be  subclinically infected and may remain carriers and excrete the 
organism (Australian Wildlife Network 2009) . While the susceptibility of g uinea pigs 
makes them suitable for experimental and diagnostic p urposes , natural infections in guinea 
pigs have not been described .  
For diagnosis in subclin ically infected wildlife species detection of antibody using an 
ELISA test in combination with detection of DNA in faeces by PCR is recommended  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 25 (Australian Wildlife  Network 2009) . Diagnosis in guinea pigs could be attempted using the 
same methods.   
7.1.5. Hazard identification conclusion  
C. burnetii  is endemic in Australia , and guinea pigs are susceptible to infection . Therefore , 
it is concluded that C. burnetii  is a hazar d in the commodity . 
7.2. RISK ASSESSMENT  
7.2.1. Entry assessment  
Natural infections of guinea pigs have not been reported . A wide range of animals are 
susceptible and the disease occurs in Australia , where cattle sheep and goats are the 
principal sources of infection . To become infected, guinea pigs would have to come into 
direct contact with birth products of infected livestock. While tick bite is another 
theoretical pathway,  ticks have not been reported naturally on  guinea pigs. Therefore, the 
likelihood of the orga nism being introduced in guinea pigs is negligible.  
7.2.2. Risk estimation  
Because the entry  assessment is negligible, the risk estimate for  C. burnetii  is negligible 
and it is not assessed to be  a hazard in the commodity. Therefore, risk management 
measures are not justified.  
References  
References marked * were sighted as abstracts in electronic data bases  
Arricau -Bouvery N, Rodolakis A (2005) . Is Q fever an emerging or re -emerging zoonosis. Veterinary 
Research , 36, 327 -49. 
Australian Wildlif e Network (2009) . Q Fever in Australian wildlife. Fact Sheet. 
http://www.wildlifehea lth.org.au/AWHN_Admin/ManageWebsite/FactSheets/UploadedFiles/119/Q%20Feve
r%20in%20Australian%20Wildlife%2027%20Jun%202009%20(1.1).pdf , downloaded 4/3/2010.  
Behymer D, Riemann HP (1989) . Coxiella burnetii infection (Q Fever). Journal of the American Veter inary 
Medical Association, 194, 764 -7. 
Hatchette T, Campbell N, Hudson R, Raoult D, Marrie TJ (2003) . Natural history of Q fever in goats. 
Vector Borne Zoonotic Diseases , 3(1), 11 -5.* 
Hawker Jl, Ayres JG, Blair L (1998) . A large outbreak of Q fever in the West Midlands, a windborne 
spread to a metropolitan area? Communicable Diseases and Public Health , 1(3), 180 -7.* 
Kelly J (2004).  Q fever . In: Coetzer JAW, Tustin RC, (eds), Infectious Diseases of Livestock, 1, Pp. 565 -72, 
Oxford University Press, Oxford.  
MAF (2008) . Unwanted organisms register. http://mafuwsp6.maf.govt.nz/uor/searchframe.htm , down loaded 
4/1/2010.  
Marin M, Raoult D (1999) . Q fever. Clinical Microbiology Reviews , 12, 518 -53. 26 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  Marrie TJ, Embil J, Yates L (1993) . Seroepidemiology of Coxiella burnetii  among wildlife in Nova Scotia. 
American Journal of Tropical Medicine and Hygiene , 49(5), 613 -5.* 
Raoult D, Fenollar F, Stein A (2002) . Q fever during pregnancy: diagnosis, treatment, and follow -up. 
Archives of Internal Medicine , 162(6), 701 -4. 
Selvaggi TM, Rezza G, Scagnelli M, Rigoli R, Rassu M, De Lalla F, Pellizzer GP, Tramarin A, Bettini C, 
Zampieri L, Belloni M, Pozza ED, Marangon S, Marchioretto N, Togni G, Giacobbo M, Todescato A, 
Binkin N (1996).  Investigation of a Q -fever outbreak in Northern Italy. European Journal of Epidemiology , 12(4), 
403-8.* 
Tissot -Dupont H, Torres S, Nezri Mea (1999) . Hyperepidemic focus of Q fever related to sheep and wind. 
American Journal of Epidemiol ogy 150(1), 67 -74,, 150(1), 67 -74.* 
Woldehiwet Z (2004) . Q fever (coxiellosis): epidemiology and pathogenesis. Research in Veterinary 
Science , 77(2), 93 -100. 
Worthington RW (2001) . New Zealand is free from Q fever. Surveillance , 28(4), 3 -4. 
  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 27 8. Leptospira  serovars  
8.1. HAZARD IDENTIFICATIO N 
8.1.1. Aetiological agent  
There are more than 200 pathogenic Leptospira  serovars , arranged in at least 23 serogroups 
(Bolin 2009) . In this document  serovars are written as though they are separate species e .g. 
Leptospira hardjo . 
8.1.2. OIE List  
Leptospirosis is a listed disease of multiple species but the  Code  does not have a chapter on 
the disease. In 2007 the Terrestrial Animal Health Standards Commission stated that 
“development of a chapter at this time is not a priority because the disease is virtually 
ubiquitous  and international trade is not considered to increase risk s to human or animal 
health. Rather than leave the title and no chapter in the Code , the commission has decided 
to delete the title” (OIE 2007).  At the OIE General Session in May 2009, the International 
Committee accepted the recommendation of the Terrest rial Animal Health Standards 
Commission and as a result the empty chapter on leptospirosis was deleted from the Code . 
8.1.3. New Zealand status  
L. hardjo, L . pomona, L . balcanica, L . copenhageni , L. ballum  and L. tarrasovi  have been 
isolated from animals in New Z ealand (Midwinter 1999) . A single isolation of L. australis  has 
been reported from a human (Thompson 1980) . In humans, serological  diagnosis indicates that 
five of the species that have been found in farm animals also infect humans, but L. balcanica  
which is associated with possums has not been diagnosed in humans (ESR 2007) . Other 
Leptospira spp. are classified  as “other exotic organisms” (MAF 2008) . 
8.1.4. Epidemiology  
Leptospirosis is not a single disease but a complex of diseases caused by many different 
leptospires. Most serovars are adapted to a particular host species in which  they may exist 
for long periods without causing clinical  signs. S pecies other than the maintenance host 
may be more resistant to infection but if infected are more susceptible to disease. In 
maintenance hosts, Leptospira  localise in the kidneys and continue to be excreted in urine 
for protracted periods.  
The organisms are shed in urine and semen and infection can occur through mucous 
membranes, venereally, by mouth or through the skin, particularly through abrasions and 
wounds (Hunter 2004) . Clinically diseased animals shed more organisms and are more 
important sources of infection than chronic carriers (Horsch 1989) . 
In accidental hosts the incubation period may be fro m 2-16 days and is followed by a 
period of bacteraemia (Hunter 2004) . The disease can be diagnosed by the isolation of the  
organism, but because this is a difficult process it is more usually diagnosed by serological 
methods. A rising titre suggests a recent infection and a stable, often low level titre 
indicates resolution or a chronic infection. The microscopic agglutinatio n test is the most 
commonly used diagnostic test and a number of variations of ELISA are also available but 28 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  generally lack serovar specificity (Bolin 2009) . Leptospirosis is seldom the cause of 
economically serious disease in animals. It is a zoonotic disease that occasionally causes 
serious disease in humans (Thornley et al. 2002) .  
Leptospira  spp. are sensitive to several antibiotics (Alt and Bolin 1996; Alt et al.  2001; 
Gerritsen et al.  1994; Gerritsen et al.  1993; Hodges et al.  1979; Murray and Hospenthal 
2004; Oie et al.  1983) . Leptospiruria has been  successfully treated using streptomycin 
treatment (Alt et al.  2001; Gerritsen et al.  1994; Hodges et al.  1979) . Streptomycin and 
penicillin have been used extensively for prophyl actic treatment of live animals, semen and 
embryos in international trade. Streptomycin was found to be the drug of choice in pigs 
and tetracycline was also effective (Alt and Bolin 1996) . 
According to Harkness et al.  (2002) guinea pigs that have been in contact with rodents 
infected with L. icterohae morrhagiae  may develop disease characterised by jaun dice and 
haemorrhages in several organs . There are innumerable reports of guinea pigs being used 
for experimental and diagnostic work but evidence of naturally occurring disease is rare. A 
few references were located indicating a low level of seropositivit y in guinea pig colonies 
(Arora and Baxi 1978/1979; Belitard o et al.  2000) . One report indicated a high prevalence 
of antibody titres to Leptospira autumnalis  in what was apparently a heavily infected 
animal colony (Natrajaseenivasan and Ratnam 1996) . No evidence was found that guinea 
pigs are maintenance hosts for Leptospira spp. 
Several Leptos pira serovars  that have not been reported in New Zealand  occur in Australia 
(Battey et al.  1964; Chappel et al.  1992; Corney et al.  1996; Corney et al.  2008; Eymann et 
al. 2007; Smythe et al.  2002) . 
8.1.5. Hazard identification conclusion  
Leptospirosis is considered by t he OIE to be an unimportant disease in the international 
trade of animals and animal products. Although g uinea pigs are susceptible to experimental 
infection with many  Leptospira  serovars  they appear to be rarely infected under natural 
conditions. Further,  guinea pigs are not recognised as maintenance hosts for any serovars. 
The likelihood that a new Leptospira  serovar could be introduced by importing clinically 
healthy guinea pigs from Australia is considered to be negligible . Therefore, Lepto spira 
spp. ar e not identified as hazard s in the commodity .  
References  
References marked * were sighted as abstracts in electronic data bases.  
Alt DP, Bolin CA (1996) . Preliminary evaluation of antimicrobial agents for treatment of  Leptospira 
interr ogans serovar pomona infection in hamsters and swine. American Journal of Veterinary Research , 
57(1), 59 -62. 
Alt DP, Zuerner RL, Bolin CA (2001) . Evaluation of antibiotics for treatment of cattle infected with Leptospira 
borgpeterseni i serovar hardjo. Journal of the American Veterinary Medical Association , 219(5), 636 -9. 
Arora BM, Baxi KK (1978/1979) . Sero -evidence of leptospirosisin Equidae, Suidae, Rodentia, and 
Lagomorpha. Indian Journal of Veterinary Pathology , 3, 52 -3.*  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 29 Battey YM, Smith DJ, Barrow GJ ( 1964) . The Epidemiology of Leptospirosis in North Queensland. Ii. 
Further Observations on the Hosts in the Mossman District. Journal of Hygiene (Lond) , 62, 485 -94.* 
Belitardo DR, Freitas JC, Muller EE (2000) . [Prevalence of leptospirosis in animals from Bi ologic Science 
Centre Londrina State University]. Semina (Londrina) , 21(1), 19 -25.* 
Bolin CA (2009).  Leptospirosis . In: OIE, (eds), Manual of Diagnostic Tests and Vaccines for Terrestrial 
Animals. Fifth edition, Vol. 1, Pp. 251 -64, OIE, Paris. 
http://www.oie.int/eng/normes/mmanual/A_summry.htm , downloaded 9/3/2010.  
Chappel RJ, Ellis WA, Adler B, Amon L, Millar BD, Zhu SS, Prime RW (1992) . Serological evidence 
for the presence of Leptospira interrogans serovar bratislava in Australian pigs. Australian Veterinary 
Journal , 69(5), 119 -20. 
Corney BG, McClintock CS, Colley J, Elder JK (1996) . Genotypes of Leptospira isolated from 
Queensland cattle. Australian Veterinary Journal , 73(2), 75 -6. 
Corne y BG, Slack AT, Symonds ML, Dohnt MF, McClintock CS, McGowan MR, Smythe LD (2008) . 
Leptospira weilii  serovar Topaz, a new member of the Tarassovi serogroup isolated from a bovine source in 
Queensland, Australia. Intenationa l Journal of Systematic and Evolu tionary Microbiology , 58(Pt 10), 2249 -52.* 
ESR (2007) . Notifiable and other diseases in New Zealand . Annual report 2007. 
http://www.surv.esr.cri.nz/PDF_ surveillance/AnnualRpt/AnnualSurv/2007AnnualSurvRpt.pdf , downloaded 
16/12/2009.  
Eymann J, Smythe LD, Symonds ML, Dohnt MF, Barnett LJ, Cooper DW, Herbert CA (2007) . 
Leptospirosis serology in the common brushtail possum ( Trichosurus vulpecula ) from urban Sydney, 
Australia. Journal of Wildlife Diseases , 43(3), 492 -7. 
Gerritsen MJ, Koopmans MJ, Dekker TC, De Jong MC, Moerman A, Olyhoek T (1994) . Effective 
treatment with dihydrostreptomycin of naturally infected cows shedding Leptospira interrogans  serovar 
hardjo subtype hardjobovis. American Journal of Veterinary Research , 55(3), 339 -43. 
Gerritsen MJ, Koopmans MJ, Olyhoek T (1993) . Effect of streptomycin treatment on the shedding of and 
the serologic responses to Leptospira interrogans  serovar hardjo  subtype hardjobovis  in experimentally 
infected cows. Veterinary Microbiology , 38(1 -2), 129 -35. 
Harkness JE, Murray KA, Wagner JE (2002).  Biology and diseases of guinea pigs . In: Fox JG, Anderson 
LC, Loew FM, Quimby FW, (eds), Laboratory animal Medicine, Pp. 203 -46, Academic Press, London.  
Hodges RT, Thomson J, Townsend KG (1979) . Leptospirosis in pigs: the effectiveness of streptomycin in 
leptospiruria. New Zealand Veterinary Journal , 27(6), 124 -6. 
Horsch F (1989).  Leptospirosis . In: Blaha T, (eds), Applied Veterin ary Epidemiology, Pp. 95 -102, Elsevier 
Science Publishers, Amsterdam.  
Hunter P (2004).  Leptospirosis . In: Coetzer JAW, Tustin RC, (eds), Infectious Diseases of Livestock, 3, Pp. 
1445 -6, Oxford University Press, Cape Town.  
MAF (2008) . Unwanted organisms reg ister. http://mafuwsp6.maf.govt.nz/uor/searchframe.htm , down loaded 
4/1/2010.  
Midwinter A (1999) . Spirochaetes in New Zealand. Surveillance , 26(3), 10 -2. 
Murray CK, Hospenthal DR (2004) . Determination of susceptibilities of 26 Leptospira  sp. serovars to 24 
antimicrobial agents by a broth microdilution technique. Antimicrobial Agents and  Chemotherapy , 48(10), 4002 -5.* 30 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  Natrajaseenivasan K, Ratnam S (1996) . An investigation of leptospirosis in a  laboratory animal house. 
Journal of  Communicable Diseases , 28(3), 153 -7.* 
OIE (2007).  Report of the meeting of the OIE Terrestrial Animal Health Standards Commission, September 
2007,, OIE, Paris. http://www.oie.int/downld/SC/2007/A_TAHSC_September%202007_introduction.pdf , 
downloaded 27/1/2007.  
Oie S, Hironaga K, Koshiro A, Konishi H, Yoshii Z (1983) . In vitro susceptibilities of five Leptospira  
strains to 16 antimi crobial agents. Antimicrobial Agents and  Chemotherapy , 24(6), 905 -8.* 
Smythe LD, Field HE, Barnett LJ, Smith CS, Dohnt MF, Symonds ML, Moore MR, Rolfe PF (2002) . 
Leptospiral antibodies in flying foxes in Australia. Journal of Wildlfie Diseases , 38(1), 182 -6. 
Thompson A (1980) . The first New Zealand isolation of Leptospira interrogans  serovar australis . New 
Zealand Medical Journal , 91(651), 28.  
Thornley CN, Baker MG, Weinstein P, Maas EW (2002) . Changing epidemiology of human leptospirosis 
in New Zealand. Epidemiology and Infection , 128(1), 29 -36.* 
  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 31 9. Exotic  Salmonella serovars and phage types  
9.1. HAZARD IDENTIFICATIO N 
9.1.1. Aetiological agent  
There are approximately 2,500 known serovars in the Salmonella  genus (Davies 2008) . 
Most of these belong to the species enterica and the subspecies enterica  and if correct 
conventions are used, the names such as Dublin  and typhimurium , which do not have 
species status, should not be italicised. The correc t name for the serovar typhimurium  is 
Salmonella enterica  subsp. enterica  serovar Typhimurium. However, in the following 
discussion, for the sake of simplicity names are italicised and abbreviated as though the 
serovar had species status e.g. Salmonella ty phimurium .  
Within many serovars there are multiple strains which can be identified by phage typing. 
Phage types are identified by the notation DT and a number. Salmonella typhimurium  
DT104 is of particular significance because it exhibits multiple resista nce to the common 
mainline antibiotics and is a threat to human and animal health (Hogue et al.  1997; Jones et 
al. 2002) . It is now widely distributed in the world.  
9.1.2. OIE lis t 
Salmonellosis is not a listed disease in the OIE Terrestrial Animal Health Code . However, 
in the OIE Manual of Diagnostic Tests and Vaccines  Salmonellosis is included in the 
section “Diseases not covered by List A and List B” (Davies 2008) . 
9.1.3. New Zealand status  
Salmonella Dublin , Salmonella abortus ovis, Salmonella gallinarum, Salmonella pullorum  
are listed on the Unwanted Organisms R egister as unwanted, notifiable organisms . While 
Salmonella Arizonae , Salmonella enteritidis  DT4 , Salmonella typhimurium  DT44 and 104 
and Salmonella spp. (exotic affecting animals) are listed as unwanted “other exotic ” 
organisms.  
Salmonella  spp. isolated in New Zealand from humans and animals, by all m ajor 
laboratories, are identified to serovar and phage type by the Environmental Science and 
Research  laboratory and recorded on a database (ESR 2009) . That database  does not 
contain any records of Salmonella  spp. isolat ions from guinea pigs .  
Salmonella typhimurium  is endemic in New Zealand in both animals and humans, but 
DT104 has only been isolated very rarely from humans  and not fr om livestock. It w as once 
isolated from three dogs in a household where the owners suffered from diarrhoea after 
returning from an overseas visit (Julian 2002) . The sporadic occurrence of Salmonella 
typhimurium  DT104 in a few cases in humans and once in dogs does not suggest that it has 
become established in the New Zealand animal populati on.  
9.1.4. Epidemiology  
There are no recognised exotic Salmonella  spp. that are unique to guinea pigs, but it is 
assumed that guinea pigs may be infected with various Salmonella  serovars. The 32 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  Salmonellas most commonly isolated from guinea pigs are Salmonella typ himurium  and 
Salmonella enteritidis  (Harkness 2009) . It is reasonable to assume that guinea pigs are able 
to be infected with a number of different Salmonella  serovars.  
Salmonella infection occurs mainly by the oral rout e particularly from faeces or food. In 
guinea pigs infections may be acute with the only sign of infection being high mortality. 
Rough hair coat, weakness, abortion, light coloured faeces and intermittent diarrhoea may 
be seen. Carriers shed the organism i ntermittently in their faeces (Harkness 2009) . 
Diagnosis is by isolation of the organism from faeces, blood, spleen, liver or other organs, 
using standard enrichment and culture methods (Davies 2008) . However, since excretion 
may be intermittent in carrier animals repeated culture attempts are necessary. Generic 
PCR methods have been developed that will identify DNA from a wide variety of 
Salmone lla serovars (Daum et al.  2002; Pathmanathan et al.  2003)  and are available 
commercially (Zoologix 2009) .  
Salmonel losis can be treated with antibiotics but emergence of antibi otic-resistant strains is 
a recognised concern in all infected species  (Jones et al.  2002) .  
Salmonellosis is a serious disease of guinea pigs and it has been suggested that for control 
of infection in a colony of guinea pigs the entire colony should be euthanized an d the 
caging and equipment sanitised (Harkness 2009) . 
9.1.5. Hazard identification conclusion  
Salmonella  serovars are distributed world -wide. A large variety of Salmonella  serovars and 
phage types are already present in New Zea land and because salmonellosis in guinea pigs 
is apparently not common, it is unlikely that healthy guinea pigs would introduce an exotic 
Salmonella  serovar or phage type. Guinea pigs have not been implicated as playing an 
important role in the transmissio n of salmonellae to humans.  
Reflecting the above, Salmonella  spp. are not identified as a hazard.  
References  
References marked * were sighted as abstracts in electronic data bases.  
Daum LT, Barnes WJ, McAvin JC, Neidert MS, Cooper LA, H uff WB, Gaul L, Riggins WS, Morris S, 
Salmen A, Lohman KL (2002) . Real -time PCR detection of salmonella in suspect foods from  a 
gastroenteritis outbreak in K err county, Texas. Journal of Clinical Microbiology , 40(8), 3050 -2. 
Davies R (2008).  Salmonellosis . In: OIE, (eds), Manual of Diagnostic Tests and Vaccines for Terrestrial 
Animals, 2, Pp. 1267 -83, OIE, Paris.  
ESR (2009) . Database of the enteric reference laboratory.  
http://www.surv.esr.cri.nz/enteric_reference/enteric_reference.php , downloaded 9/9/2009.  
Harkness JE (2009) . Personal communication to MAFBNZ.  
Hogue A, Agula F, Johnson R, Petersen K, Saini P, Schlosser W (1997).  Situation Assessment: 
Salmonella Typhimurium DT 104, United States Department of Agriculture, Food Safety and Inspection 
Service, Washington DC 20250. http://www.fsis.usda.gov/OPHS/stdt104.htm .  
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 33 Jones YE, Chappell S, McLaren IM, Davies RH, Wra y C (2002) . Antimicrobial resistance in Salmonella  
isolated from animals and their environment in England and Wales from 1988 to 1999. Veterinary Record , 
150, 649 -54. 
Julian A (2002) . Quarterly review of diagnostic cases: Gribbles Veterinary Pathology: Dog s. Surveillance , 
29(3), 28.  
Pathmanathan SG, Cardona -Castro N, Sanchez -Jimenez MM, Correa -Ochoa MM, Puthucheary SD, 
Thong KL (2003) . Simple and rapid detection of Salmonella strains by direct PCR amplification of the hilA 
gene. Journal of  Medical Microbiol ogy, 52(Pt 9), 773 -6*. 
Zoologix (2009) . Molecular Diagnostic Testing for Animals. Rodent and Rabbit Salmonella Assay Data 
Sheet, http://www.zoologix.com/rodent/Datasheets/Salmonella.h tm, downloaded 10/3/2010.  
   34 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  10. Weed seeds  
10.1. HAZARD IDENTIFICATIO N 
10.1.1.  Aetiological agent  
All plant seeds and plant material.  
10.1.2.  OIE list  
Not listed.  
10.1.3.  New Zealand status  
This section only relates to exotic plants.  
10.1.4.  Epidemiology  
Weed s and weed seeds could be found attached to the hair of guinea pigs. Large seed 
heads and pieces of plant material would be easily visible and could be removed before 
shipment but small seeds would not be visible. It is unlikely that seeds or plant m aterial 
would remain attached for  long periods.  
Seeds are specifically adapted to survive unfavourable environmental conditions and most 
will at least survive from one growing season to another. Many will survive for several 
years and germinate when favourable conditions occur. Most seeds are highly resistant to 
dehydration, particularly those from plants adapted to survival in desert or hot dry climates 
and most seeds retain viability better in dry conditions but some are specifically adapted to 
remain viable in water. Mimosa glomerata  seeds s urvived 221 years in the herbarium of 
the Museum National d’Histoire Naturelle in Paris. Lupinus arcticus  seeds frozen in a 
leemings burrow that was dated as 10,000 years old germinated within 48hours when 
placed in favourable conditions  (Anonymous undated) . Some seeds are adapted to 
environments subjected to periodic fires and survive or are activated by fires. Others are 
adapted to be dispersed by water including those adapted to salt water.  
Some plants can replicate asexually and are able to be grown from cuttings, and could 
grow from pieces of plants introduced on animals.  
Weed see ds can survive passage through animal’s digestive systems and are passed out in 
faeces (Katovich et al.  undated) . One hundred percent of radioopaque markers were voided 
from the gut of 25 human subjects in 25 -169 hours (Hinton et al.  1969) . It is not known 
how long seeds could be retained in guinea pi g’s digestive tracts. However , it is unlikely to 
be longer than in humans .  
10.1.5.  Hazard identification conclusion  
It is concluded that weed seed could be introduced on a guinea pig’s hair or in their faeces. 
Therefore , weed seeds are identified as a hazard  in the commodity.   
Ministry for Primary Industries  Biosecurity risk assessment : Guinea pigs  ● 35 10.2. RISK ASSESSMENT  
10.2.1.  Entry assessment  
Seeds and plant material could be introduced attached to a guinea pig’s  hair and in faeces, 
Therefore , the likelihood of entry in the commodity is non -negligible  
10.2.2.  Exposure assessment  
Weed seeds could become detached from a guinea pig’s hair or released in faeces. They 
are generally resistant to most environmental conditions and may remain dormant until 
conditions are favourable for germination. Therefore, the likelihood that seeds could 
germinate and grow if released into a suitable environment is non -negligible.  
10.2.3.  Consequence assessment  
As a result of the release of exotic weed seeds , new exotic invasive  weeds could be 
introduced and become established with subsequent deleterious effects on the environment 
and the economy.  
10.2.4.  Risk estimation  
Since entry, exposure, and consequence assessments are non -negligible, the risk estimate 
for weeds and weed seeds is non -negligible and they are classified as hazards in the 
commodity. Therefore, further risk management asse ssment could be undertaken . 
10.3. RISK MANAGEMENT  
The following points have been considered when drafting options to manage the risks 
associated with introduction of weeds and weed seeds  on the commodity:  
 Under normal circumstances, where guinea pigs are fed a v aried diet of fresh fruit 
and vegetables, processed pel lets and high quality hay, weed  seeds would not be 
expected on their coat or in their intestines.  
 To minimise any risk of weed seeds in faeces it would be possible to quarantine 
guinea pigs for 3 days  where they have access to only high quality hay (without 
weed seeds), fresh fruit and vegetables or processed pellets.  
One or a combination of the following options could be considered in order to effectively 
manage the risks:  
Option 1.  
Careful inspectio n on the day of export to ensure the guinea pigs are free from 
contamination with weeds and weed seeds, combined with an owner’s declaration that they 
have been fed on a high quality diet not including weed seeds for the past 3 days.  
Option 2.  
Guinea pigs could be quarantined for 3 days where they have access to only high quality 
hay (without seeds), fresh fruit and vegetables or processed pellets.  36 ● Biosecurity risk assessment : Guinea pigs  Ministry for Primary Industries  While in quarantine g uinea pigs could be housed in cages with wire mesh floors without 
bedding or , if bedding is required,  wood shavings, sawdust, artificial bedding materials 
blankets etc could be used .  
 
References  
Anonymous (undated) . Germination> Dormancy and life -span of seeds. In encyclopaedia Britannica. 
Britannica online. http://britannica.com/eb/article -75927?hook+606897 , downloaded 17/7/2009.  
Hinton JM, Lennard -Jones JE, Young AC (1969) . A new method for studying gut transit times using 
radioopaque markers. Gut, 10(10 ), 842 -7. 
Katovich J, Becker R, Doll J (undated) . Weed seed survival in livestock systems. A publication of 
University of Minnesota extension service http://www.manure.umn.edu/assets/Wee dSeedSurvival.pdf , 
downloaded 17/7/2009.