Import risk analysis: Hatching eggs 
from chickens  (Gallus gallus) from 
the European Union, Canada, the 
United States of America, and 
Australia  
 
Draft for Public Consultation 
 
 
 
    
May 2008 
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Import risk analysis : Hatching eggs from chickens (Gallus gallus)  from the 
European Union, Canada, the United States of America, and Australia 
 
DRAFT FOR PUBLIC CONSULTATION 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MAF Biosecurity New Zealand 
Ministry of Agriculture and Forestry 
Wellington 
New Zealand 
 
 
 
 
 
 
 
May 2008 
 
 
  
 
This page is intentionally blank   
 
Ministry of Agriculture and Forestry 
Te Manatu Ahuwhenua, Ngaherehere 
Pastoral House 
25 The Terrace 
P O Box 2526 
Wellington 
New Zealand 
 
Telephone: +64 4 894 0100 
Facsimile: +64 4 894 0133 
Internet: http://www.biosecurity.govt.nz 
 
 
 
MAF Biosecurity New Zealand 
 
 
Import risk analysis: Hatching eggs from chickens (Gallus Gallus)  from the European Union, Canada, 
the United States of America and Australia 
 
 
 
 
 
May 2008 
 
 
 
 
 
 
Draft for Public Consultation 
 
 
 
 
 
 
  
 
This page is intentionally blank DRAFT FOR PUBLIC CONSULTATION 
 
i  
Contents  
1. EXECUTIVE SUMMARY  1 
2. INTRODUCTION  3 
2.1. Commodity Definition 3 
2.2. Background 3 
2.3. Methodology 3 
3. ORGANISM RISK ANALYSES  10 
3.1. Avian Influenza Virus 10 
3.2. Avian Paramyxoviruses (APMV-1 to 9) 14 
3.3. Pneumovirus 19 
3.4. Infectious Bronchitis Virus 23 
3.5. Avian Infectious Arthritis 24 
3.6. Avian Nephritis Virus 25 
3.7. Salmonellae 26 
3.8. Ornithobacterium Rhinotracheale 38 
3.9. Mycoplasma Iowae 42 
4. REFERENCES  44 
 DRAFT FOR PUBLIC CONSULTATION 
ii Contributors to this Risk Analysis 
 
 
1. Authors 
 
Bruce Simpson  Consultant Biosecurity Ltd, 
Palmerston North, New Zealand 
 
Stephen Cobb Senior Adviser, Pre-
clearance risk analysis (Animals) MAF Biosecurity 
New Zealand, Wellington 
 
 
2. Internal Peer Review 
 
Howard Pharo  Team Manager, Pre-
clearance risk analysis (Animals)  MAF Biosecurity 
New Zealand, Wellington  
Stuart MacDiarmid  Principal International 
Adviser, Risk Analysis  MAF Biosecurity 
New Zealand, Wellington  
Joanne Thompson  Consultant 
 Fielding, New Zealand  
José Derraik  Senior Adviser, Pre-
clearance risk analysis (Human health)  MAF Biosecurity 
New Zealand, Wellington  
Sandy Toy  Senior Adviser, Pre-
clearance risk analysis (Indigenous fauna)  MAF Biosecurity 
New Zealand, Wellington  
Rachelle Linwood  Senior Adviser, Import 
health standards (Animals)  MAF Biosecurity 
New Zealand, Wellington  
Leone Basher  Senior Adviser, Import 
health standards (Animals)  MAF Biosecurity 
New Zealand, Wellington  
 
3. External Scientific Review 
 
David Marks Consultant Livestock solutions and 
services Ltd., Auckland  
Neil Christensen Consultant Avivet Ltd., Palmerston 
North DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft ri sk analysis for chicken hatching eggs • 1 1. Executive Summary 
 
This risk analysis considers the biosecurity ri sks associated with the importation of hatching 
eggs of chickens ( Gallus gallus ) from the European Union, Canada, the United States of 
America, and Australia.   From a preliminary hazard list of organisms, t hose that were considered to be potential 
hazards in the commodity were subjec ted to individual risk assessments. 
 As a result of the individual risk assessments, it was concluded that the risk in the commodity 
was non-negligible for th e following organisms: 
 
• avian influenza viruses 
• type 1 avian paramyxoviruses 
• Salmonella  Gallinarum-Pullorum 
• Salmonella  Typhimurium DT104 
• Salmonella  Enteritidis  
• Ornithobacterium rhinotracheale 
 
These organisms were classified as hazards in  the commodity and options for the effective 
management of these risks have been presented.   Risk management options discussed in this 
document include:  
• Eggs could come from breeding estab lishments and hatcheries following the 
standards documented in appendix 3.4.1 of the OIE Terrestrial Animal Health 
Code  (1) (or equivalent).  
• The breeding establishments could be either free from avian influenza for at 
least 21 days prior to the collection of the eggs, or the parent flock could be 
tested for group A influenza viruses with negative results. 
• The breeding establishments could have routine surveillance for avian 
paramyxovirus-1, and be free from avian paramyxovirus-1 for at least 21 days 
prior to the collection of the eggs. 
• The breeding establishments could be free from fowl typhoid, pullorum 
disease, Salmonella Enteritidis and have no evidence of Salmonella  
Typhimurium DT104. 
• The flock could be free from Ornithobacterium rhinotracheale  on the basis of 
testing a sample of laying birds. 
• Eggs could be transported to New Zealand in clean unused packaging. 
• Eggs could be hatched and chickens be held in quarantine in a MAF-approved 
avian transitional facility until required tests for avian influenza viruses and avian paramyxovirus-1 are completed with  negative results and a biosecurity 
clearance given. 
 DRAFT FOR PUBLIC CONSULTATION 
2 • Draft risk analysis for chicken hatchi ng eggs MAF BIOSECURITY NEW ZEALAND   
This page is intentionally blank .DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft ri sk analysis for chicken hatching eggs • 3  
2. Introduction 
 
This risk analysis examines the biosecurity ri sks posed by the importation of hatching eggs of 
chickens ( Gallus gallus ) from specified countries. 
 
2.1. COMMODITY DEFINITION 
 
The commodity is hatching eggs of chickens ( Gallus gallus ) from the European Union, 
Canada, the United States of America, and Aust ralia. The eggs will be clean (free of faeces) 
when collected, unwashed and have intact shells  (uncracked). Following collection, the eggs 
will be disinfected in accordance with appendix 3.4.1 of the OIE Terrestrial Animal Health 
Code  (1).  
 
2.2. BACKGROUND 
 
Import Health Standards (IHSs) are available fo r chicken hatching eggs from Australia, Great 
Britain, the United States of America, and Canada. These were de veloped prior to the 
implementation of the current poli cy of requiring scientifically ba sed risk analyses as the basis 
for development of all IHSs. A company within  the New Zealand poultry industry wishes to 
import chicken hatching eggs from Europe. It is considered appropriate that the scope of the 
risk analysis required to s upport the development of the IHS for that importation be 
broadened to include the range of countries sp ecified in the commodity definition. This will 
ensure that all IHSs for chicken hatchi ng eggs have the same technical base. 
 
2.3. METHODOLOGY 
 
The methodology used in this risk analysis follows the guidelines as described in MAF 
Biosecurity New Zealand’s Import Risk Analysis Animals and Animal Products (2)1 and in 
section 1.3 of the OIE Terrestrial Animal Health Code  (1).  
 The risk analysis process used by the MAF is summarised in Figure 1.   
2.3.1 Preliminary hazard list  
 
The hazard identification process begins with the collation of a list of organisms possibly 
associated with the commodity. Table 1 shows thes e organisms, together with some of the key 
information considered in determining whether or not each organism should be considered further. This list was compiled from the text Diseases of Poultry  11
th Edition, Editor Saif, 
Y.M., and from searches of the scientific literature.  
                                                 
1 Risk analysis projects started after 12 April 2006 will fo llow procedures as outlined in Biosecurity New Zealand’s Risk Analysis 
Procedures Version 1  which can be seen at http://www.b iosecurity.govt.nz/files/ pests-dis eases/surveillance-review/risk-analysis-
procedures.pdf DRAFT FOR PUBLIC CONSULTATION 
4 • Draft risk analysis for chicken hatchi ng eggs MAF BIOSECURITY NEW ZEALAND  Figure 1 . The risk analysis process. 
Not considered to 
be a hazard in 
this risk analysisyesno
yesHAZARD IDENTIFICATION
List of organisms and 
diseases of concern
Is the organism likely to be associated with 
the pathway?
Is the organism 
present in New 
Zealand?
Is there a control 
programme in 
New Zealand?
Would the organism 
on the pathway 
increase the existing 
exposure in NZ?no
yesnoEntry Assessment
Likelihood of potential 
hazard entering New 
Zealand on the pathway
Exposure/Establishment 
Assessment
Likelihood of exposure and 
establishment in NZ
Consequence Assessment
Likely impacts on the 
economy, environment and 
human health in NZ
Risk Estimation
Organism/disease is 
considered to be a hazard 
in this risk analysisRISK ASSESSMENT
Apply measures that 
reduce risk to
acceptable levelRISK MANAGEMENT
How does assessed 
risk compare to 
acceptable level of 
risk?What is the 
acceptable 
level of risk?
What is the effect of 
each measure on 
the level of riskWhat 
measures are 
available?non-negligible
non-negligible
non-negligibleRisk Estimation
Not considered to 
be a hazard in this 
risk analysis
negligiblenegligiblenegligible
Are there 
different strains 
overseas?Potential 
hazard in this 
risk analysisyes
yes no
no
no
Could the organism 
bring a pathogen/
disease not present 
in New Zealand?
noyes
 
 
   DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft ri sk analysis for chicken hatching eggs • 5 Table 1.  Organisms potentially  associated with the commodity 
 
Organism/Disease Present in 
New 
Zealand? Evidence of 
more 
virulent 
strains 
overseas?1 Under official 
control or 
unwanted?2 Infection in 
eggs?3 Needs further 
consideration?  
Orthomyxoviridae 
Avian influenza Yes  Yes Exotic strains 
notifiable Yes  Yes 
Paramyxoviridae 
Avian paramyxovirus 1  
(APMV-1) Yes  Yes Notifiable  
(Exotic strains) Yes Yes 
APMV-2 No? Yes? Other exotic 
organism Yes? Yes 
Pneumoviruses No? N.A. None Yes? Yes 
Herpesviridae 
Marek’s disease Yes  Yes Other exotic 
organism 
(Exotic strains) No No 
Laryngotracheitis Yes Yes None No No 
Coronaviridae 
Infectious bronchitis Yes Yes Unwanted 
(exotic strains) Yes  Yes 
Adenoviridae 
Group I avian adenoviruses 
(Inclusion body hepatitis) Yes No None Yes No 
Group II avian adenoviruses 
(Avian adenovirus splenomegaly) No N.A.  None No No 
Group III avian adenoviruses 
(Egg drop syndrome) Yes No None Yes No 
Poxviridae 
Avipoxvirus Yes No None No No 
Circoviridae Gyrovirus (Chicken 
infectious anaemia) Yes No None Yes No 
Birnaviridae 
Infectious bursal disease No N.A. Notifiable  No No 
Alphaviruses 
Equine encephalitides No N.A. Notifiable No No 
Flaviviridae West Nile virus No N.A. None No No 
Reoviridae Rotavirus Yes No None No No 
Viral arthritis, tenosynovitis Yes Yes None Yes Yes 
Picornaviridae 
Avian encephalomyelitis Yes No None Yes No 
Astroviridae Astrovirus (Avian nephritis 
virus) Uncertain N.A. None Yes Yes 
 DRAFT FOR PUBLIC CONSULTATION 
6 • Draft risk analysis for chicken hatchi ng eggs MAF BIOSECURITY NEW ZEALAND  Table 1. (continued) 
 
Organism/Disease Present in 
New 
Zealand? Evidence of 
more virulent 
strains 
overseas?1 Under official 
control or 
unwanted?2 Infection in 
eggs?3 Needs further 
consideration?  
Retroviridae 
Leucosis/sarcoma complex 
viruses Yes No None Yes No 
Reticuloendotheliosis Yes No None Yes No 
Hepesviruses 
Big liver and spleen disease 
virus No Yes Other exotic 
organism No No 
Bacteria associated with enteric a nd generalised infections in birds 
Salmonellae Yes/No Yes S. Pullorum 
and S. 
Gallinarum 
notifiable. Other exotic serovars and 
phage types 
unwanted Yes Yes 
Campylobacter  spp.  Yes No None Yes No 
Escherichia coli Yes No None Yes No 
Bacteria commonly associated with respiratory disease in birds 
Pasteurella multocida Yes Yes None No No 
Pasteurella gallinarum No N.A. None No No 
Riemerella anatipestifer Yes No None No No 
Ornithobacterium rhinotracheale No N.A. Other exotic 
organism Yes Yes 
Haemophilus paragallinarum No N.A. Other exotic 
organism No No 
Bordetella avium No N.A. Other exotic 
organism No No 
Mycoplasma gallisepticum Yes No None Yes No 
Mycoplasma synoviae Yes No None Yes No 
Mycoplasma iowae No N.A. Other exotic 
organism Yes Yes 
Pseudomonas  spp. Yes No None Yes No 
Intracellular bacteria 
Mycobacterium tuberculosis Yes No None No No 
Mycobacterium avium Yes No None No No 
Other mycobacteria Yes 
(Some) Yes Other exotic 
organism (exotic strains) No No 
Other bacteria 
Francisella tularensis No N.A. Other exotic 
organism No No 
Megabacteria Yes No None No No 
Gram positive contaminants (e.g. 
staphylococci/streptococci/ 
enterococci) Yes No None No No 
Proteus /Providencia  group Yes No None Yes No 
Klebsiella  spp. Yes No None Yes No 
Acinetobacter  spp. Yes No None Yes No 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft ri sk analysis for chicken hatching eggs • 7 Table 1. (continued) 
 
Organism/Disease Present in 
New 
Zealand? Evidence of 
more virulent 
strains 
overseas?1 Under official 
control or 
unwanted?2 Infection in 
eggs?3 Needs further 
consideration?  
Other bacteria (cont) 
Citrobacter  spp.  Yes No None Yes No 
Flavobacterium  spp. Yes No None Yes No 
Alcaligenes  spp. Yes No None Yes No 
Serratia  spp. Yes No None Yes No 
Hafnia alvei Yes No None Yes No 
Bacillus  spp. (Not Bacillus 
anthracis ) Yes No None Yes No 
Clostridium perfringens Yes No None Yes No 
Chlamydophila psittaci Yes No None Yes No 
Spirochetes 
Borrelia anserina  (Avian 
spirochaetosis) No N.A. Other exotic 
organism No No 
Borrelia burgdorferi  (Lyme 
disease) No N.A. Other exotic 
organism No No 
Brachyspira  spp. Yes No None No No 
Rickettsial agents 
Coxiella burnetii No  N.A. Notifiable 
organism No No 
Aegyptianella pullorum  No N.A. None No No 
Other Rickettsia Yes/No Yes Some are in the 
in register No No 
Fungi and yeasts  
Enterocytozoon bieneusi Yes No None No No 
Encephalitozoon cuniculi Yes N.A. None Yes No 
Other fungi and yeasts  Yes/No Yes None No No 
Internal parasites  
Nematodes, cestodes, 
protozoa  Yes/No Yes None No No 
External parasites  
Ticks, mites, lice  Yes/No Yes Unwanted 
(Some genera) No No 
 
1 More virulent exotic strains are recognised where either stra in typing of New Zealand isolates allows differentiation from 
more pathogenic types recognised in other countries or where descriptions of the disease in New Zealand allow it to be 
recognised as less virulent than disease episodes in other c ountries. Where host-specific st rains are recognised overseas 
but not in New Zealand, these are treated as “more virulent” in the compilation of this table. 
 
N.A. = Not applicable because assessment of strain variations is not relevant to this process when the organism is not 
recognised as present in New Zealand.  
2 Based on the information from the register of unw anted organisms at http://www.biosecurity.govt.nz/pests-
diseases/registers-lists/unwanted organisms/  
3 For the purposes of this analysis, infection of eggs is consider ed to take place if the literature contains references to vert ical 
transmission of the organism or to infection in eggs.  
 DRAFT FOR PUBLIC CONSULTATION 
8 • Draft risk analysis for chicken hatchi ng eggs MAF BIOSECURITY NEW ZEALAND  2.3.2 Risk analysis for the importation of  hatching eggs from chickens ( Gallus 
gallus ) from the European Union, Canada, the United States of America, and 
Australia 
 
In section 3 of this analysis, for each organism  identified as requiring further consideration in 
Table 1, the epidemiology is discussed, includ ing a consideration of the following questions: 
 
1. Whether the imported commodity could act  as a vehicle for the introduction of 
the organism? 
2. If the organism requires a vector, whet her competent vectors might be present 
in New Zealand? 
3. Whether the organism is exotic to Ne w Zealand but likely to be present in 
exporting countries?  
4. If it is present in New Zealand, 
i. whether it is "under official cont rol", which could be by government 
departments, by national or regional pest management strategies or by a 
small-scale programme, or 
ii. whether more virulent strains are kno wn to exist in other countries? 
 
For any organism, if the answer to question on e is “yes” (and the answer to question 2 is 
“yes” in the cases of organisms requiring a vector) and the answers to either questions three or 
four are “yes”, it is classified as a potential hazard requiring risk assessment. 
 Under this framework, organisms that are pres ent in New Zealand cannot be considered as 
potential hazards unless there is evidence that strains with higher pathogenicity are likely to 
be present in the commodity to be imported.  Therefore, although there may be potential for 
organisms to be present in the imported commod ity, the risks to human or animal health are 
no different from risks resulting from the presence of the organism in this country already.   
 In the case of this risk analysis, an exception to this framework is made for the treatment of 
salmonellae considered of partic ular concern to human health. Salmonella Typhimurium DT 
104 and S. Enteritidis (various phage types) have been isolated in New Zealand but are not 
established in poultry. Codes of practice in the poultry industry (3) are such that importation 
of poultry stock infected with  these organisms would requ ire imposition of control and 
eradication procedures that woul d result in very high costs to the importer and, potentially, the 
broader industry.  If importation of the commodity is considered likely to result  in an increased exposure of 
people to other potentially zoonot ic organisms already present in New Zealand, then these 
organisms are also considered  to be potential hazards. 
 
In line with the MAF Biosecurity New Zealand and OIE risk analysis methodologies, for each 
potential hazard requiring risk assessment  the following analysis is carried out: 
  Risk Assessment 
  
 a) Entry assessment -  the likelihood of the organism being imported in the 
commodity.  
 b) Exposure assessment - the likelihood of animals or humans in New 
Zealand being exposed to  the potential hazard. 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft ri sk analysis for chicken hatching eggs • 9  c) Consequence assessment - the consequences of entry, establishment or spread 
of the organism.  
 d) Risk estimation - a conclusion  on the risk posed by the organism 
based on the release, exposure and consequence assessments.  If the risk estimate is non-negligible, then the organism is classified as a hazard. 
 It is important to note that all of the above steps may not be nece ssary in all risk assessments.  
The MAF Biosecurity New Zealand and OIE risk analysis methodologies ma ke it clear that if 
the likelihood of entry is negligible for a potential hazard, then the risk estimate is 
automatically negligible and the remaining step s of the risk assessment need not be carried 
out.  The same situation arises where the li kelihood of entry is non-negligible but the 
exposure assessment concludes that the likelihoo d of exposure to suscep tible species in the 
importing country is negligible, or where both entry and exposure are n on-negligible but the 
consequences of introduction are concluded to be negligible.  
  
2.3.3 Risk management 
 
For each organism classified as a hazard, 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 desc ribed alongside options of similar, lesser, or 
greater stringency where available.   In addition to the options pr esented, unrestricted entry or 
prohibition may also be considered for all h azards.  Recommendations for the appropriate 
sanitary measures to achieve the effective management of risks are not made in this 
document.  These will be determined when an import health standard (IHS) is drafted. As 
obliged under Article 3.1 of the WTO Agreem ent on Sanitary and Phytosanitary Measures 
(the SPS Agreement) the measures adopted in IH Ss will be based on international standards, 
guidelines and recommendations where they ex ist, except as otherw ise provided for under 
Article 3.3 (where measures providing a higher le vel of protection than international standards 
can be applied if there is scientific justification, or if there is a level of protection that the 
member country considers is more appropriate following a risk assessment). 
  
2.3.4 Risk communication 
 
This draft import risk analysis is issued for a six-week period of public consultation to verify 
the scientific basis of the ri sk assessment and to seek stakeholder comment on the risk 
management options presented.  Stakeholders are also invited to present alternative risk 
management options they consider necessary or preferable.   Following this period of public consultation on th is draft document, a review of submissions 
will be produced and a decision-making committee will determine whether any changes need to be made to this draft risk analysis.    Following this process of consultation and re view, the Imports Standards team of MAF 
Biosecurity New Zealand will decide on the appropriate combination of sanitary measures to ensure the effective management of identified risks.  These will be presented in a draft IHS which will also be released for a six-week period of stakeholder consultation.  Stakeholder submissions in relation to the draft IHS will be  reviewed before a final IHS is issued.  DRAFT FOR PUBLIC CONSULTATION 
10 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND   
3. Organism Risk Analyses 
3.1. AVIAN INFLUENZA VIRUS 
3.1.1. Hazard identification 
3.1.1.1.  Aetiological agent 
Avian influenza (AI) viruses are influenza A viruses within the family Orthomyxoviridae. 
These viruses are characterised by antigenic surf ace glycoprotein haemagglutinin (types H1 – 
16) and neuraminidase (N1 – 9) (4). Strains of AI are commonly se parated into highly 
pathogenic strains (HPAI) and low pathogeni c strains (LPAI) on the basis of their 
pathogenicity in chickens. All HPAI virus isolat es have been subtypes H5 or H7 but not all 
H5 or H7 isolates have b een highly pathogenic (4, 5).  
 
3.1.1.2.  OIE list 
Notifiable avian influenza (NAI) viruses are on the OIE List. NAI refers to any avian 
influenza virus of H5 or H7 subtypes or any AI  virus with pathogenici ty above limits set in 
chapter 2.7.12 of the OIE Terrestrial Animal Health Code  (1). 
 
3.1.1.3.  New Zealand status 
Avian influenza H5 and H7 are listed in Ne w Zealand’s unwanted or ganisms register.  
 AI viruses have been isolated from healt hy wild mallard ducks in New Zealand (6-9). 
Subtypes identified have included H4N6, H1N3, and H5N2 (6, 10). The H5N2 isolates were shown to be non-pathogenic (6, 10).   A survey in the 1990s found no evidence of AI vi rus infection in 54 pige ons trapped at three 
locations in New Zealand or in samples from  55 native birds (11). These negative findings 
received support from a 2003 se rological survey of 560 pigeons  (domestic and wild) sampled 
from Auckland, Wellington, Christchurch, and Dunedin (12). AI viruses have never been 
diagnosed in New Zealand domestic poultry.  
3.1.1.4.  Epidemiology 
Three reviews of the epidemiology of AI (5, 13, 14) and chapter 2.7.12 of the OIE Terrestrial 
Animal Health Code  (1) form the main bases for this section.  
 The main means of spread is through virus passe d in faeces or respiratory secretions. Spread 
may be directly into areas occupied by poultr y, through contamination of water, or through 
carriage on fomites. Outdoor poultry flocks are more vulnerable to exposure to wild birds, and 
are therefore affected with AI more frequently than flocks maintained indoors. AI virus may 
be maintained in poultry flocks as LPAI or LP AI may be introduced in to an area by infected 
wild birds, mainly waterfowl, with gulls and sea birds playing a lesser role. Because of the 
relatively high prevalence of AI viruses in mi gratory waterfowl, commercial flocks located 
outdoors and on migratory pathways appear to be at highest risk . Secondary spread is through 
transfer of infection from faeces, most co mmonly by people moving between flocks or 
properties. Spread of AI within live-bird mark ets has been found to be an important means of DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 11 dissemination between poultry farms in both Asia (15-17) and the north eastern United States 
(18, 19). Market hygiene (incl uding control of interspecies co ntact) has been found to be a 
critical factor in controlling spread within these environments.   Virulent H5 and H7 strains apparently arise by mutation from low pathogenic strains some 
time after the transfer of infection from the wild host to poultry. The ability of these mutated viruses to infect multiple tissues results in th eir high pathogenicity. Th e pathogenicity of AI 
virus strains varies depending upon the species  infected. This has been illustrated by 
differences in responses of differe nt species to experimental infec tions with an H5N1 strain of 
AI (20) and differences in clin ical and pathological presentation of natural AI infections in 
different species (21).   In the reviews by Alexander (22) and Senne (23)  of reports of avian influenza over the period 
from 1997 to 2002, ten subtypes of AI are listed  as having been identified in chickens. Of 
these, four are NAIs, being either H5 or  H7. The remaining six non-NAIs are discussed 
briefly below:  
• H1N1 subtype was identified in chicke ns in Canada in 1998 (23). It was a 
virus of this subtype that cause d the pandemic in humans in 1918. 
• H2N2 has been reported from the eggs of healthy chickens in the United States 
(24). An H2N2 virus was responsible for a human influenza pandemic in 1957. 
• H3N6 subtype has been identified in ch ickens, quail, ducks and caged birds in 
Asia (22, 25), and in chickens in the United States (23) but no reports 
attributing pathogenicity to this  subtype have been located. 
• An incident of H6N2 infec tion in flocks of laying chickens in California was 
associated with respiratory disease and decreased egg production (23).  
• H9N2 subtype was recorded from chickens  in Europe, Iran, Saudi Arabia (22), 
and the United States (23). Guo et al. (26) cite severa l reports of H9N2 
infecting humans in China and Hong Kong.  Viruses of this subtype have been 
reported as causing epidemics of avia n influenza in turkeys in the United 
States (27) and chicke ns in Iran (28).   
• Birds infected with H10N7 virus in Ontario, Canada showed respiratory 
disease and kidney necrosis (23).  
 Horimoto and Kawaoka (29) reviewed cross-species infection with AI, particularly cross infections between ducks, pigs, and humans, a nd the mechanisms (adaptation and genetic re-
assortment) for the development of strains with  high levels of virulence in humans. These 
processes are aided by the intensive mix of  humans, pigs, and ducks found in Asia. 
 
3.1.1.5.  Hazard identification conclusion  
NAI viruses must be considered to have the pot ential to lead to the development of disease 
and are classified as potential hazards in the commodity.   There are also a number of non-NAI subtypes with the capacity to cause disease in poultry. 
The full potential for such dis ease relationships is not unders tood and genetic changes in non-
NAI strains, or encounters with new poten tial hosts, may result in disease.  
 Therefore all avian influenza viruses are clas sified as potential hazards in the commodity. 
 DRAFT FOR PUBLIC CONSULTATION 
12 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.1.2. Risk assessment 
3.1.2.1.  Entry assessment 
AI virus has been isolated from the internal cont ents of eggs from naturally-infected layer and 
breeder flocks with clinical di sease and from an infected laye r flock with no clinical signs 
(30). Unpublished work by Brugh cited by Swayne and Beck (31) identified HPAI virus in 85 
to 100 percent of eggs laid on days 3 and 4 following experimental i noculation. Although no 
reports of transmission of infection to chicks via infected eggs have been located, movement 
of egg trays and associated fomites was a significan t risk factor in the spread of AI infection 
during an epidemic in the Netherlands in 2003 (32).  
 
The entry assessment for AI virus in chicken eggs is considered to be non-negligible. 
 
3.1.2.2.  Exposure assessment 
AI virus is spread via respiratory aerosols, f aeces, fomites, and people, with the faecal-oral 
route being the most important. Any infection in hatchlings derived from imported eggs is 
likely to spread to other birds through either direct  or indirect contact. 
 The exposure assessment for AI viruses is  considered to be non-negligible. 
 
3.1.2.3.  Consequence assessment 
There is a high likelihood that the importation of HPAI viruses could result in epidemic 
disease in New Zealand poultry with high morta lities and disruption of the poultry industries 
and export trade in poultry products.   The low susceptibility of birds in the wild and the imposition of control measures in the event 
of an incident of HPAI in fection are likely to limit c onsequences on wild birds.  
 The potential for LPAI strains to cause diseas e in birds in New Zealand cannot be excluded; 
nor can the possibility of LPAI strains b ecoming pathogenic following mutation or genetic 
recombination.  The intensive mixing of humans, pigs, and ducks  seen in Asia which is considered to 
contribute to the development of  new strains of influenza vi rus pathogenic to humans, does 
not occur in New Zealand. The likelihood of adap tation or genetic re-assortment of AI viruses 
leading to the development of new strains cap able of causing serious disease in humans is 
considered to be very low. The epidemiology of the development of strains of AI virus 
pathogenic to humans is such that AI viruses in this commodity are not considered to be a 
potential hazard to human health.  AI viruses in this commodity are considered to be a hazard to the New Zealand poultry 
industry and to the economy. There may be effe cts on other birds, incl uding native species, 
particularly water fowl, but such effect s are likely to be relatively small.  
 The consequence assessment for AI is  considered to be non-negligible.  
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 13 3.1.2.4.  Risk estimation 
Because entry, exposure, and consequence assess ments are non-negligible, the risk estimate is 
non-negligible and avian influenza viruses are classified as a hazard in the commodity.  
Therefore, risk management measures can be justified.  
3.1.3. Risk management 
 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  
i. Eggs could come from breeding establishm ents and hatcheries compliant with the 
standards documented in appendix 3.4.1 of the OIE Terrestrial Animal Health Code  (1) 
(or equivalent) and be transpor ted in new packing material.  
 
ii. Eggs could come from an AI-free country, zone, or compartment and be derived from 
parent flocks which had been kept in an esta blishment free of all AI viruses for at least 
21 days prior to and at the time of the collection of the eggs.  
 
iii. As indicated in article 3.8.9.6 of the OIE Terrestrial Animal Health Code (1), birds 
could be randomly tested using virus dete ction or isolation te sts, and serological 
methods, and the frequency of testing should be  based on the risk of infection and at a 
maximum interval of 21 days. Tests methods  used could detect all group A influenza 
viruses. The number of birds sample d would depend on the expected minimum 
prevalence of infection and th e level of confidence required for its detection. The only 
report found that documented w ithin-flock seroprevalence rate s is that of Al-Natour and 
Abo-Shehada (33) in Jordan. In flocks from  which 30 sera were tested using an ELISA 
targeting subtype H9N2, between 1 (3 percen t) and 30 (100 percent)  sera were positive 
from individual flocks. 95 percent confiden ce that the seroprevalence in the flock is 
below 5 percent is a reasonable basis for determining sample numbers.  
 
iv. Eggs could be hatched under secure quarant ine conditions in New Zealand and a sample 
of hatchlings tested prior to clearance.  
 
v. Cloacal or choanal swabs from live birds or hatchlings could be cultured for AI virus 
using methods described in the OIE Manual of Diagnostic Tests and Vaccines for 
Terrestrial Animals  (34) or tested by PCR methods th at detect group A influenza viruses 
(35). 
 
vi. Birds and/or hatchlings could be kept in contact with specific pathogen free chickens 
during the quarantine period and then these ch ickens tested for infection with AI using 
methods identified above. DRAFT FOR PUBLIC CONSULTATION 
14 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND   
3.2. AVIAN PARAMYXOVIRUSES  (APMV-1 TO 9) 
3.2.1. Hazard identification 
3.2.1.1.  Aetiological agent 
Nine “prototype” virus strains of  paramyxovirus are recognised in birds. They are in the genus 
Avulavirus  (35), are differentiated on serologi cal grounds, and identified as avian 
paramyxoviruses 1 to 9 (APMV-1 to 9) (36).   Pathogenic strains of APMV-1 cau se Newcastle disease (ND) a nd strains have, in the past, 
been differentiated on the basis of their ability  to cause chick embryo mortality (37) which 
provides a guide to the severity of disease caus ed by the virus strains. The OIE criteria for 
reporting an outbreak of ND provide  for differentiation of isolates of APMV-1 on the basis of 
either intra-cerebral pat hogenicity in day-old chicks or de monstration of specific amino acids 
at specific locations in the virus (34). 
 
3.2.1.2.  OIE list 
Newcastle disease is included in th e OIE list of notifiable diseases.  
 
3.2.1.3.  New Zealand status 
APMV – 1 (exotic strains) (Newcastle disease)  is listed as notifiable in the unwanted 
organisms register.   APMVs -2, -3 and -5 are listed as “other e xotic organisms” in the unwanted organisms 
register. 
 Newcastle disease has never been diagnosed in New Zealand. A non-pathogenic strain of 
APMV-1 is present (38). Pharo et al. (39) reviewed New Zealand’ s status with respect to 
Newcastle disease. APMV-1 has been isolated  from mallard ducks, chickens, and one parrot. 
All New Zealand APMV-1 isolates have been demonstrated to be of low virulence.  
 In addition to the APMV-1 isolations, APMV-4  was identified in samples from 17 ducks. 
Serological tests in ducks were positive for APMV-1, 2, 3, 4, 6, 7, 8, and 9 but, because of the cross reactivity that occurs between the prot otype strains (36), only APMV-1, 4 and 6 could 
be concluded to be present. Test ing did not include APMV-5 (40). 
 Stanislawek et al. (41) interpreted serological results fr om caged birds, wild birds, and poultry 
as indicative of the presence of APMV-1 in all categories and suggestive (but not 
confirmatory) of the presence of APMV-2 in wi ld birds. Because of cross reactivity between 
APMVs, the presence of other APMVs in caged  or wild birds could not be excluded.  
 
3.2.1.4.  Epidemiology 
Newcastle disease virus (NDV) is  widely distributed and there is almost universal use of ND 
vaccines in commercial poultry throughout the wo rld (36). Transmission between birds may 
be through either inhalation or ingestion. Ge ographic spread may be aided by movement of 
live birds, contact between animal groups, and movement of people and/or fomites. 
Contamination of waterways, ponds, and surface water has also been proposed as means of DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 15 spread of NDV (42, 43). Infection in groups of  birds may present with signs varying from 
high morbidity and high mortality to inapparent  infections depending upon viral strain and 
host species. There are reports of ND causing m ild transient conjunctivitis and, occasionally, 
fever in humans. Reports of human to huma n transmission have not been located (36). 
 Mutation of an APMV-1 virus of low virulen ce was proposed as the most likely source of 
high virulence virus that cau sed a Newcastle disease outbr eak in Australia (44, 45). 
 Live vaccines, using lentogenic virus, are fre quently used for induction of a relatively short-
lived initial immune response in young chickens. Immunity ma y be reinforced by the later 
administration of live vaccine of greater potenc y and/or by use of an inactivated product. 
Vaccine viruses have been recovered from youn g chickens up to 19 days after vaccination 
(46-48). While vaccination provide s protection against serious di sease, it does not always 
prevent infection or excre tion of the virus (36).  
 Up to 1988, APMV-1 infection had been report ed from 241 species of birds from 27 orders 
with differences in clinical presentation even  between species within the same genus (49). 
Further identifications have taken place since th at time and Alexander (36) proposed that the 
majority of, if not all, birds are susceptible to infection.  APMV-2 (also called Yucaipa virus) is widesp read in poultry, particularly chickens and 
turkeys (36). In these species it commonly cau ses mild respiratory disease, although more 
severe disease has been reported in turkeys (5 0). In wild and caged birds APMV-2 has been 
recorded from Europe, Asia, Africa, and American  countries with most isolations being from 
passerine birds (36). Disease associated with  APMV-2 has not been reported from non-
poultry species.   APMV-3 was first identified in turkeys in th e United States and, subsequently in other 
countries. In turkeys it causes egg production prob lems. There have been no reports of natural 
infections of chickens. APMV-3 has been is olated relatively frequently from caged and 
quarantined birds, mainly psittacines but also  passerines. APMV-3 strains infecting caged 
birds differ from those infecting turkeys (51).   APMV-4 viruses have been isolated only from ducks and geese and have not been associated 
with disease (36, 40).  APMV-5 has been reported only from pet budgeriga rs in a unique epizootic in Japan between 
1974 and 1976 (52).  APMV-6 has been isolated from turkeys, in wh ich it may cause mild disease, and from ducks 
and geese in which disease associ ation has not been reported (36). 
 APMV-7 has been reported from pigeons, dove s, turkeys, and ostriches. It has been 
associated with mild respiratory disease in  turkeys (36) but searches for reports of 
pathogenicity in other species have not been successful.  APMV-8 and 9 have been reported from ducks  and geese (36) but reports suggesting 
pathogenicity have not been located. 
 
 DRAFT FOR PUBLIC CONSULTATION 
16 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.2.1.5.  Hazard identification conclusion  
Based on host specificity and their ability to ca use disease,  both APMV-1 and APMV-2 are 
classified as potential hazards in the commodity. 
 
3.2.2. Risk assessment 
3.2.2.1.  Entry assessment 
Pospisil et al. (53) and Capua et al. (54) findings of lentogenic a nd virulent Newcastle disease 
virus respectively, in eggs and chickens from infected hens support contentions that APMV-1 
may be transmitted transovarially. Chen and Wang (55), on the basis of epidemiological 
evidence and results from experimental infec tion of chicken embryos, concluded that egg 
borne transmission of NDV was possible. McFerran et al. (56) found that Yucaipa virus and 
Bangor virus strains (both member s of APMV-2) isolated from finches grew in eggs and that 
some embryos survived.   Vertical transmission of APMVs is regarded as controversia l (36) and an OIE recognized 
expert in Newcastle Disease (Dr.Paul Selleck, CSIRO, Australian Animal Health Laboratory) 
was approached for an expert opinion.  Dr Selleck (pers. comm.
2) commented that he had 
been able to isolate virulent NDV from the al bumen of eggs laid by vaccinated and then 
experimentally challenged chickens, indicati ng that, under certain circ umstances, NDV can be 
transmitted vertically. In unvacci nated chickens, infection with  virulent NDV causes almost 
immediate cessation of laying due to infecti on of the oviduct. Eggs laid by unvaccinated 
chickens that are infected with  virulent NDV are unlikely to hatc h as the virus will kill them. 
Therefore the opportunity to spread in eggs is  reduced or eliminated. With non-virulent NDV, 
virus replication is confined to the gut and/or re spiratory tract. It is possible that non-virulent 
NDV may contaminate an egg surface but if the e gg is well washed or the surface disinfected 
the chances are greatly reduced. APMV-2 shoul d fall in the same category as non-virulent 
NDV but there is no direct experimental  evidence one way or the other.  
 The entry assessment for APMV-1 in the comm odity is therefore considered to be non-
negligible. As there is no evidence for vertic al transmission of APMV-2, the entry assessment 
for APMV-2 is considered to be negligible.  
3.2.2.2.  Exposure assessment 
If hatching eggs carrying exotic strains of APMV-1 were imported the most likely outcome 
would be the introduction of the virus into the hatchery. The poten tial routes of spread from 
an infected hatchery could include  mechanical spread (primarily  by the movement of people 
and equipment), movement of infected birds from  the hatchery (live or dead), and airborne 
spread. 
 MAF’s 2001 import risk analysis on APMV-1 in hatching eggs
3 concluded that the exposure 
pathways for APMV-1 are primarily those that re ly on direct or indire ct contact with faecal 
material. Spread by humans or human activities associated with poultry flocks is the most 
likely way that APMV-1 virus imported in ha tching eggs would escape from the hatchery 
environment and result in exposure of avian species in New Zealand.  
                                                
 
2 Selleck P. Virologist, CSIRO Australian  Animal Health Laboratory, Victoria, Aust ralia. E-mail to Stephen Cobb, September 2006 
3 Pharo H (2001) Import risk analysis: avian paramyxovirus type 1 in he ns' hatching eggs, MAF, Wellington. 
See:www.biosecurity.govt.nz/pests-diseases /animals/risk/avian-paramyxovirus-ra.pdf 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 17 The exposure assessment for APMV-1 is ther efore considered to be non-negligible. 
 
3.2.2.3.  Consequence assessment 
The potential consequences of introduction of new strains of APMV-1 to New Zealand vary 
greatly. The current lentogenic st rain is reported to spread relatively slowly in poultry and 
introduction of a strain that spreads rapidly co uld disrupt current sero -surveillance (57). The 
establishment of additional strains of APMV -1 might also increase the likelihood of the 
mutation of a virus to velogenic form. The in troduction of a velogeni c strain would have 
serious consequences for the poul try industry and could result in  substantial mortalities in 
wild and/or caged birds.   There are reports indicating that both velogenic and vaccine strains of APMV-1 (36, 58, 59) 
from poultry can cause disease in humans. APMV-1 infections in humans have most 
commonly been reported in association with c onjunctivitis, but some re ports have referred to 
chills, headaches and fever. Given the pres ence of a lentogenic strain of APMV-1 in 
New Zealand, the mild and transient nature of the disease and the infrequency of such reports, 
any consequences to human health are likely to be minor.   The introduction of APMV-1 in the commodity  would be associated with non-negligible 
consequences to the New Zealand poultry indus tries and to human health. The consequence 
assessment for APMV-1 is therefore considered to be non-negligible. 
 
3.2.2.4.  Risk estimation 
Because the entry, exposure, and consequen ce assessments are non-negligible, the risk 
estimate is non-negligible and APMV-1 is cl assified as a hazard in the commodity.  
Therefore, risk management measures can be justified.  
3.2.3. Risk management 
 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  
i. Eggs could originate from flocks in a c ountry, zone or compartment free of APMV-1. 
 
ii. Eggs could be derived from flocks in whic h vaccination for Newcastle disease using live 
vaccines has not taken place within the four w eeks prior to collection of eggs, and from 
flocks that have been certified as being free from APMV-1.  
 
iii. The flock from which eggs are to be collected could be tested for evidence of APMV-1. 
Such a sample could be sufficiently large to provide confidence that APMV-1 is not present. 
 
iv. Eggs could be hatched under secure quarant ine conditions in New Zealand and material 
from embryos, dead-in-shell chicks, or hatc hlings could be tested for APMV-1 before 
release, with the sample size being chos en according to the required confidence in 
detecting the expected minimum prevalence.  Hatched chickens could be held in contact 
with chickens of New Zealand origin from flocks shown to be free of APMV-1, which 
are then tested for APMV-1 after the period of exposure.  DRAFT FOR PUBLIC CONSULTATION 
18 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND   
Test procedures available in clude culture for APMV using methods described in chapter 
2.1.15 of the OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals  (34). Any 
APMV isolate could be serotyped, particularly for APMV-1, paying partic ular attention to the 
antigens and antisera used to avoid erroneous iden tification (34). Alternat ively, on the basis of 
the epidemiology and release assessment pres ented above, it could be assumed that any 
APMV isolated is APMV-1.   Haemagglutination tests, haemagglutination inhi bition tests, and ELISAs can be used in the 
serological diagnosis of Ne wcastle disease.  The OIE Manual  does not prescribe a test for 
international movement of animals or anim al products although the haemagglutination 
inhibition test is listed as an “alternative test”
 suitable for the diagnosis  of disease within a 
local setting, and for use in the import/export of animals after bilateral agreement (34).  Validation of tests has mainly focussed on AP MV-1 in poultry and Alexander (36) comments 
on the need for care in reagent selection. V accination may cause positive serological test 
results. 
 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 19 3.3. PNEUMOVIRUS 
3.3.1. Hazard identification 
3.3.1.1.  Aetiological agent 
Family: Paramyxoviridae; Subfamily: Pneumovirinae; Genus: Metapneumovirus , avian 
pneumovirus (APV) has proved difficult to culture a nd, for that reason, much of the research 
involving identification of  infected birds has used PCR technology.  
 
3.3.1.2.  OIE list 
Not listed. 
 
3.3.1.3.  New Zealand status 
Turkey rhinotracheitis virus is listed  in the unwanted organisms register.  
 No evidence of turkey rhinot racheitis (TRT) or of swollen head syndrome (SHS) has been 
reported in New Zealand.   
3.3.1.4.  Epidemiology 
Avian pneumovirus subgroups 
The terms avian pneumovirus and turkey rh inotracheitis virus are interchangeable. 
Phylogenetic analyses indicate that APV subgr oup C (APVc) is distinct from APV subgroups 
A and B (APVa and APVb) (60-63). Two isolates  originating from turkeys in France in 1985 
had distinct nucleotide sequences more clos ely resembling those of APVa and APVb and 
were proposed to be classified as subgroup D ( 64). As these two turkey  isolates are the only 
ones classified in subgroup D, this subgroup is no t considered further in this risk analysis.  
 
APVa and APVb have a wide geographic dist ribution through Africa,  Asia, Europe, and 
South America (62, 65) where they  cause swollen head disease of chickens and rhinotracheitis 
of turkeys. APVc is recognised in the United St ates where it was first described in Colorado, 
from where it has been eradicated and is now confined to Minnesota, North Dakota, South Dakota, Iowa, and Wisconsin (65, 66). APVc was also reported in a ssociation with coughing 
and a drop in egg production in a fl ock of Muscovy ducks in France (67). 
 Serological testing of 10,000 chicken and tu rkey sera in Canada during 1990-92 found no 
evidence of avian pneumovirus (69). Since that tim e there have been no reports of serological, 
clinical, or pathological ev idence of APV in Canada. The only report located suggesting 
possible evidence of APV in Canada identified  APV RNA in a single pooled sample from 16 
snow geese ( Chen caerulescens ) shot in Saskatchewan (66).  
 Chickens are not refractory to experimental inf ection with APVc (70) but natural infections of 
chickens with APV have not been reported from North America and Halvorson (pers. 
comm.
4) stated that “we” (the College of Veterina ry Medicine at the University of Minnesota) 
have never detected APVc (or any other pneum ovirus) in chickens in Minnesota even though 
approximately 50 percent of the tu rkey flocks are seropositive.  
                                                 
4 Halvorson, D., College of Veterinary Medicine, University of Minnesota, USA. E-mail to Bruce Simpson, 9 May 2006. DRAFT FOR PUBLIC CONSULTATION 
20 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND   
Conclusion 1 
Based on the evidence that APVc is genetical ly distinct from APVa and APVb, and the 
absence of evidence that it causes natural infections in chickens, APVc is not classified as a 
potential hazard in the commodity.  
Conclusion 2 
There is no evidence that either APVa or APVb  are present in the United States or Canada. 
 
APVa and APVb 
APV causes turkey rhinotracheitis, a serious disease which may have both high morbidity and 
mortality, and it is a major cont ributory factor in SHS of chicke ns (65). In turkeys, morbidity 
and mortality can be high (up to 100 percent a nd 50 percent respectively). In chickens, SHS is 
less dramatic with morbidity and mortality rates of 4 percent and 2 percent respectively being more common and then usually in association wi th other pathogens. Direct contact is thought 
to be the main means of transmission betw een birds (65). Population seroprevalence data 
presented by a number of authors (66, 71) indi cate seroconversion of vi rtually all birds in 
individual infected flocks. This was the case for six turkey flocks tested using ELISA after the development of clinical disease,  three broiler flocks prior to the development of disease in 
Italy (72) and farmed ostriches in Zimbabwe (68). Introduction of a high-passage strain of 
APV to 0.2 percent of birds in each of ten fl ocks of 2 – 4 week old turkeys, each with 20,000 
to 50,000 birds, was considered to have resulted in transfer of infection to all birds within 10 
days (73).  
 
The description of SHS provided by Pattison et al. (74) in the United Kingdom was one 
commencing with coughing then developing to opisthotonus, incoordina tion, swelling around 
the eyes and over the head, discharges from ey es and/or ears, and a green diarrhoea. Although 
the morbidity rate was low (ar ound 1 percent), the case mortality rate approached 100 percent. 
Of 14 broiler breeder farms observed, 10 seroco nverted to APV, SHS developed on six, and a 
decrease in egg production was noticed on a further three.  
 
Horizontal transmission 
Spread of APV is thought to be through direct contact. Two experiments testing the ability of 
APV to spread between groups of turkeys found that  the virus did not bri dge gaps of two feet 
(75) or one metre (76) between cages of groups of birds even though virus was being 
transmitted between challenged and unchallenged bi rds within the infected cages and the flow 
of air in the rooms was from infected cages to ward those uninfected. Suspicions that fomites 
and movement of people may contribute to local  spread (65) are supported by evidence that 
APVc can survive for several weeks at 4°C, fo r at least seven days while drying at room 
temperature (77) and in poultry litter for at le ast three days at room temperature (20-25°C) 
and 14 days at 8°C (78). The role of wild birds in the dissemination of infection is 
speculative.   
Vertical transmission 
The proposition that APVs may be transmitted ve rtically is supported by reports of pathology 
and viral RNA in the uterus and oviduct following experimental infections  of turkeys (79) and 
chickens (80) with isolates of APVa and AP Vb respectively. In bot h reports, the viral 
presence was associated with gross pat hology of the reproductive tract including egg 
peritonitis and in the second report (80) intr avenous administration of virus had lead to 
70 percent of birds in a group of 24 becoming ill and over 50 percent developing diarrhoea. 
One bird died, two were killed while moribund and another six birds were killed between 
seven and 11 days post-infection while ill.  APV antigen was detected in the oviduct DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 21 epithelium of six of the birds that died  or were killed. In the report by Jones et al. (79) APV 
was detected in the epithelium of the reproduct ive tract on days seven and nine post-infection 
but virus was not identified in the ovary. They  concluded that there was no evidence to-date 
(1988) that the virus is transmitted through eggs. While Cook et al. (80) suggested that 
infection of the reproductive tract might contribute to the decrease in egg production 
commonly seen in APV infection, and the faults  in egg quality observed less frequently, they 
made no comment on its significance with respect to egg borne transmission.  
 Three other reports of experimental infection of  chickens with European isolates of APV and 
investigations of pathology of, and possible AP V presence in, tissues of  the reproductive tract 
have been located (81, 82). No evidence of APV infection (viral recovery, positive immunofluorescent staining, or pathology) was found in tissues of the reproductive tract.  
 Shin et al. (83) obtained APVc PCR positive results from pooled egg contents from turkey 
breeder flocks and from choanal swabs from da y-old poults at a hatchery. However, attempts 
to culture APV from the choanal swabs and from eggs were unsuccessful. Clinical disease consistent with APV infection had been obser ved in breeder flocks five weeks prior to 
hatching of the affected poults. Comparable re ports from regions where APVa and/or APVb 
are present have not been located.  No reports of avian pneumovirus in Australia have been found and it is generally accepted 
that the virus is not pres ent in that country (65). 
 
3.3.1.5.  Hazard identification conclusion  
APVs subgroup A and subgroup B are classified  as potential hazards in the commodity. 
 
On the basis of phylogenetic differences a nd the lack of evidence that APV subgroup C 
infects chickens under field conditions, APV subgr oup C is not classified as a potential hazard 
in the commodity.   
3.3.2. Risk assessment 
3.3.2.1.  Entry assessment 
There is no firm evidence that APV can be transmitted through eggs, however, the 
observations by Shin et al. (83) of APV RNA in turkey eggs and young turkeys, and their 
epidemiological observations, s upport the hypothesis th at this may be possible for APVc. The 
findings of APV antigen in the reproductive tracts  of chickens and turkeys (79, 80) suggest 
that such a transmission route may also be av ailable for APV in Europe. However, pathology 
of the reproductive tract of chic kens has been observed only in birds with severe disease.  
 Given the uncertainty in publis hed literature surrounding vert ical transmission of APVs, 
Dr. Richard E. Gough (Department of Avian Virology, VLA Weybri dge, United Kingdom) 
was approached for an expert opinion. Dr. Gough commented (pers. comm.
5) that virtually all 
the reports describe laboratory studies in which birds were infected with  large doses of virus 
either intravenously or intraocu larly rather than natural infec tion. His view was that, whilst 
replication of the virus can take place in th e reproductive tract of ch ickens, there is no 
evidence that the virus can be transmitted via the egg contents. The most compelling evidence 
for the vertical transmission of APV is the study by Shin et al. (2002) (83) in neonatal 
                                                 
5 Gough RE. Dept. of Avian Virology, VLA Weybridge, United Kingdom. E-mail to Stephen Cobb, October 2006. DRAFT FOR PUBLIC CONSULTATION 
22 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  turkeys, originating from breeders infected with APVc virus, in which PCR positive products 
were detected in egg contents and newly hatche d chicks. These results had been discussed at 
several meetings and the fact that live virus was not isolated from the samples has caused some people to question the validity of the results. As far as Dr. Gough was aware, these 
results had not been confirmed elsewhere.   Reflecting these comments from Dr. Gough and the lack of evidence supporting vertical 
transmission of APVa or APVb, the entry assessment for APVa and APVb in the commodity is therefore considered to be negligible.   
3.3.2.2.  Risk estimation 
Because the entry assessment is negligible, th e risk estimate is negligible and APVa and 
APVb are not classified as hazards in the comm odity.  Therefore, risk management measures 
are not justified.   DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 23  
3.4. INFECTIOUS BRONCHITIS VIRUS 
3.4.1. Hazard identification 
3.4.1.1.  Aetiological agent 
Infectious bronchitis virus is a Coronavirus  within the Coronaviridae.  
3.4.1.2.  OIE list 
Infectious bronchitis is included in the OIE list of notifiable diseases. 
 
3.4.1.3.  New Zealand status 
Infectious bronchitis virus (IBV)  is endemic in New Zealand ( 84, 85) with viruses appearing 
to fall into four serotypes distinct from thos e viruses tested from ot her countries (86, 87). 
Vaccination is now widespread and a high proportion of birds are serologically positive. 
 Infectious bronchitis (exotic strains) is li sted on the register of unwanted organisms. 
 
3.4.1.4.  Epidemiology 
Infectious bronchitis is a coronavirus diseas e of chickens. Chickens are the only species 
recognised as being naturally infected with IB V and in which it causes disease. Very similar 
viruses have been isolated from pheasants. IBV did not cause disease in pheasants, turkeys or 
starlings when administered experimental ly (88). Although IBV causes pathology of the 
oviduct (89-91) and embryonated eggs  are routinely used for cultu re of IBV (88), literature 
searches have found only one suggestion of virus infection of eggs from infected hens (an 
unreferenced comment by Cavanagh and Naqi (88)).  Literature searches have failed to find 
other reports of the isolation of IBV from eggs or reports suggesting vertical transmission.  
 
3.4.1.5.  Hazard identification conclusion  
With the only traceable reference to IBV inf ecting eggs being an unreferenced comment by 
Cavanagh and Naqi (88), and with an inability to locate any reports suggesting that vertical transmission of IBV takes place, exotic strains of IBV are not classified  as a potential hazard 
in the commodity. 
 DRAFT FOR PUBLIC CONSULTATION 
24 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.5. AVIAN INFECTIOUS ARTHRITIS 
3.5.1. Hazard identification 
3.5.1.1.  Aetiological agent 
Avian infectious arthritis is caused by reoviruses.  
 
3.5.1.2.  OIE list 
Avian infectious arthritis is not included in the OIE list of notifiable diseases. 
 
3.5.1.3.  New Zealand status 
Avian infectious arthritis is not list ed in the unwanted organisms register. 
 The first report of reoviruses from New Zeala nd poultry (92) was from fertile eggs with no 
association with disease. Subse quently, reovirus was isolated fr om broiler chickens in a flock 
suffering a mortality rate in excess of 6 per cent associated with respiratory disease and 
atrophy of both the thymus and bursa (93). Ho well (94) reported di agnoses of reovirus 
infections in birds with tenos ynovitis and diarrhoea. Earlier re ports from routine surveillance 
for evidence of reovirus infec tion in poultry recorded positiv e serology and the presence of 
disease (95). Later reports did not  include reference to disease but did record vaccination and 
a high prevalence of pos itive titres (96).  
 Although Green et al. (92) concluded that their five  isolates were serologically 
indistinguishable they also propos ed that it was likely that other serotypes would be present in 
New Zealand. No reports of further serotypi ng of reoviruses from New Zealand, or of 
comparing New Zealand isolates with t hose from overseas, have been located. 
 
3.5.1.4.  Epidemiology 
In his review, Rosenberger (97) states that reovirus infectio ns of birds are common around the 
world. Most infections are subc linical, however, reovirus has been  associated with arthritis, 
tenosynovitis, respiratory, hepatic, enteric, and other diseases. The viruses may spread readily 
both horizontally and vertically and there ar e strain variations based on serotypes and 
pathogenicity.    Both live-attenuated and inactivated vaccines are used for the control of disease associated 
with reoviruses. Vaccines derived for a single strain have been used with success in many 
parts of the world (97), suggesting that the protective immune response may not be closely 
related to the antig en(s) responsible for differe ntiation of serotypes.  
 
3.5.1.5.  Hazard identification conclusion  
Given the range of pathology that has been asso ciated with reoviruses in New Zealand, the 
worldwide prevalence of subclinical infections  of poultry and other birds, and the large 
number of birds that have been imported to New Zealand without biosecurity measures that 
would prevent the entry of virus, the proposal by Green et al. (92) that other serotypes will be 
present remains likely.  On the above basis it is conclude d that reoviruses ar e not a potential hazar d in the commodity.  DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 25  
3.6. AVIAN NEPHRITIS VIRUS 
3.6.1. Hazard identification 
3.6.1.1.  Aetiological agent 
Avian nephritis virus is in the Avastrovirus genus of the Astroviridae. Culture of avian 
nephritis virus (ANV) is difficult, with chic ken kidney cells being the most commonly used 
medium, and even then growth and induction of cytopathic changes appear to be influenced 
by conditions in cell cultures and the strain of ANV (98).  
 
3.6.1.2.  OIE list 
ANV is not included in the OIE list of notifiable diseases. 
 
3.6.1.3.  New Zealand status 
ANV is not listed in the unwanted organisms register. 
 ANV has not been isolated in New Zealand but an tibodies to the virus ha ve been identified in 
pooled sera tested overseas and renal pathology c onsistent with the disease has been observed 
(94).   
3.6.1.4.  Epidemiology 
ANV infections are commonly subclinical or as sociated with only mild clinical signs 
including transient diarrhoea in one-day-old ch ickens, reduced weight gain from one to two 
weeks of age, and runting and/or nephropathy in older birds (98). There are few reports of 
disease in the literature. The virus is widely distributed in  many countries with evidence 
coming from serological surveys such as thos e in England (99), Irel and (100), and Hungary 
(101). Surveys have also identified the pres ence of the virus in SPF flocks (102). ANV is 
transmitted through direct or indirect contact and there is only circumstantial evidence 
suggesting vertical transmission (98).   Although the published evidence for ANV in New Zeal and is scant, it is consistent with the 
situation in other countries prior to active su rveillance for the organism. On the basis of 
Howell’s report (94) of positive serology and pathology consistent  with ANV infection, it is 
concluded that ANV is present in this country.  
3.6.1.5.    Hazard identification conclusion  
On the basis that ANV is present in New Zeala nd and that the strain(s ) present are able to 
cause disease, it is concluded that ANV is  not a potential hazard in the commodity. 
 DRAFT FOR PUBLIC CONSULTATION 
26 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.7. SALMONELLAE 
3.7.1. Salmonellae – General 
3.7.1.1.  Hazard identification 
3.7.1.1.1.  Aetiological agent 
As members of the Enterobacteriaceae, salm onellae are motile gram-negative rods that 
ferment glucose and other sugars , and are oxidase negative.  
 The Salmonella  genus contains over 2,400 serotypes. Nomenclature now places most 
salmonellae of veterinary relevance in the sub-species Salmonella enterica  subspecies 
enterica . Over 2,300 serotypes fall within this s ubspecies. The commonly used names (e.g. 
Salmonella Typhimurium) identify serotypes within the Salmonella enterica  enterica sub-
species. Some of these serotypes are furthe r partitioned on the basis of phage type. 
Nomenclature of Arizona spp. or Salmonella arizonae  has changed over the years but 
Salmonella enterica arizonae  and Salmonella enterica diarizonae  are now considered 
subspecies within Salmonella enterica . Salmonella enterica arizonae  contains over 300 
serotypes (103).  
3.7.1.1.2.  OIE list 
The only Salmonella  serotype affecting poultry and incl uded in the OIE list of notifiable 
diseases is S. Gallinarum-Pullorum. 
 
3.7.1.1.3.  New Zealand status 
The salmonellae designated as unwanted organisms are S. Gallinarum, S. Pullorum, 
S. Abortusovis, S. arizonae , S. Dublin, S. Typhimurium DT 104, S. Typhimurium DT 44, 
S. Enteritidis PT 4 and Salmonella  spp. (exotic, affecting animals).  
 
3.7.1.1.4.  Epidemiology 
 
Salmonella Abortusovis  
S. Abortusovis is strongly host adapted to sheep. Reports of natural inf ection in species other 
than sheep and goats have not been located.  
Salmonella Dublin  
S. Dublin is host adapted to cattle with limited in fections occurring in other species. This is 
reflected in the data on Salmonella  serotypes involved in “livestock incidents” in the United 
Kingdom.  For example, during 2002 over 80 percent of Salmonella  cases in cattle were 
attributed to S. Dublin, whilst less than 1 percent of porcine salmonellosis cases were 
associated with S. Dublin and a smaller proportion ( not reported) in chickens (104). 
 
Salmonella  Typhimurium PT 44 
Few reports of the isolation of S. Typhimurium PT 44 have been found. Searches of data from 
national Salmonella  surveillance programmes available on the internet revealed reports of S. 
Typhimurium PT 44 from Australia but not from  any other country. In the reports discovered 
all isolations have been from humans or cattle . Isolations have come from most states in 
Australia but the numbers of cases per year in both cattle and humans are small. No reports of 
S. Typhimurium PT 44 in birds have been located. 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 27 Salmonella arizonae 
Nomenclature applied to S. arizonae  (Arizona spp.) has undergone changes which have 
resulted in Salmonella enterica  subspecies III being partitioned to IIIa ( S. enterica arizonae ) 
and IIIb ( S. enterica diarizonae ) (105). Serological typing desi gnation has also changed with 
moves from the use of Arizona  antisera to Salmonella  antisera. Designations used here will be 
those based on Salmonella  antisera. Serotypes within these subspecies have not been named. 
 Three major epidemiological groups are id entifiable within th e subspecies III: 
1. S. arizonae  serotypes 18:Z
4,Z32 and 18:Z 4,Z23 cause serious disease in turkeys. Chickens 
are affected infrequently and infection of humans, sheep, and dogs, have also been reported 
(106-108). 
2. S. diarizonae  serotypes 61:k:1,5 and 61:1,v:5 are co mmon is sheep and there have been 
small numbers of isolations of each from hu mans, snakes, and other reptiles (106, 107). 
3. Snakes, turtles, other reptiles, and amphibians are infected by a wide range of serotypes of 
S. arizonae  (106, 107). Weiss (107) reported the iden tification of 51 serotypes from snakes 
with 17 of those also being reported from humans. Of the 72 serotypes identified from 
humans, 17 were also identified in snakes , three from sheep, and one from cattle. 
 
3.7.1.1.5.  Hazard identifi cation conclusion 
On the basis of host specific ity and/or host preference, S. Abortusovis, S. Dublin, S. 
typhimurium PT 44, and S. arizonae  and diarizonae  (other than S. arizonae  serotypes 
18:Z 4,Z32 and 18:Z 4,Z23) are not classified as potential hazards in the commodity and are 
excluded from further considera tion in this risk analysis.  
 S. Gallinarum -Pullorum, S. arizonae  serotypes 18:Z
4,Z32 and 18:Z 4,Z23, S. Typhimurium 
DT104, S. Enteritidis PT4, and Salmonella  spp. (exotic, affecting animals) are classified as 
potential hazards in the commod ity. In addition, all salmonellae reported to be egg borne will 
be considered.  DRAFT FOR PUBLIC CONSULTATION 
28 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.7.2. Salmonella enterica subsp. enteri ca serovar Gallinarum-Pullorum 
3.7.2.1.  Hazard identification 
 
3.7.2.1.1.  Aetiological agent 
This name now covers the organisms previously known as Salmonella Gallinarum and 
Salmonella Pullorum. This is a highly host adapted, non-motile Salmonella  in sero-group D 
(109). Because of changes in nomenclature a nd because of the existence of chicken and 
turkey host-adapted strains, the literature is dominated by references to S. Gallinarum and S. 
Pullorum.  
3.7.2.1.2.  OIE list 
S. Gallinarum-Pullorum is included in the OIE list of notifiable diseases. 
 
3.7.2.1.3.  New Zealand status 
Both S. Gallinarum and S. Pullorum are listed in the unwanted organisms register. 
 S. Gallinarum has not been diagnosed in New Zeal and and, following an extensive eradication 
programme operated within th e commercial poultry industries,  S. Pullorum was last 
diagnosed in 1985.  
3.7.2.1.4.  Epidemiology 
The natural hosts for Salmonella enterica subsp . enterica serovar Gallinarum-Pullorum ( S. 
Gallinarum-Pullorum) are chickens. The organi sm occurs in most countries. Following 
infection, flock morbidity and mortality can be  highly variable. Transovarial infection does 
take place and resulting chicks ma y die in incubators. Clinical signs in adult birds may vary 
from none to severe with high mortality. Disease outbreaks have been reported from turkeys and a small number of other species. Transmi ssion can occur both horizontally and vertically, 
with carrier birds playing an important role in sp reading the disease (109). 
 
3.7.2.1.5.  Hazard identifi cation conclusion 
S. Gallinarum -Pullorum is classified as a poten tial hazard in the commodity.  
 
3.7.2.2.  Risk assessment 
3.7.2.2.1.  Entry assessment 
S. Gallinarum-Pullorum has been eradicated from commercial flocks in the USA, Canada, 
Australia, and most of the countries in West ern Europe (110). Outbreaks do still occur in 
some countries with incidents reported to the OIE from Fran ce, Italy, and Denmark during 
2004 (111). Control or eradicati on programmes generally focus on commercial flocks and it is 
possible that flock infections ar ise from non-commercial birds.  
 The entry assessment is considered to be non-negligible.  
3.7.2.2.2.  Exposure assessment 
Vertical transmission is a recognise d component of the epidemiology of S. Gallinarum-
Pullorum and horizontal transmi ssion within a hatched group is  highly likely. Although most 
commercial hatcheries maintain high levels of biosecurity protection, this cannot be relied 
upon to prevent early spread fr om an infected flock.  
 The exposure assessment is consid ered to be non-negligible. 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 29 3.7.2.2.3.  Consequence assessment 
S. Gallinarum-Pullorum infection within a flock could result in direct losses through illness 
and mortality. There may also be consequentia l losses due to control measures and disruption 
of international trade.   Infection may affect birds other than Gallus gallus  but losses are likely to  be restricted to the 
poultry industry and, possibl y, non-commercial poultry. S. Gallinarum-Pullorum is highly 
host adapted to chickens and, to a lesser extent , turkeys. Clinical signs are seldom seen in 
other species (109). S. Gallinarum-Pullorum does not cause  disease in humans or other non-
avian species.  The consequence assessment is c onsidered to be non-negligible. 
 
3.7.2.2.4.  Risk estimation 
Because the entry, exposure, and consequen ce assessments are non-negligible, the risk 
estimate is non-negligible and S. Gallinarum-Pullorum is classified as a hazard in the 
commodity. Therefore, risk management measures can be justified. 
3.7.2.3.  Risk management 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  
i. The likelihood of eggs carrying S. Gallinarum-Pullorum could be greatly reduced by 
testing birds in the laying flock to ensure that they do not carry infection and importing 
eggs only from flocks recognise d by the appropriate veterina ry administration as being 
free of infection. 
 
ii. Assurance could be required that eggs come from breeding establishments and 
hatcheries which are recognised as being free from fowl typhoid and pullorum disease 
and are compliant with the standards documented in appendix 3.4.1 of the OIE 
Terrestrial Animal Health Code  (1) (or equivalent). 
 
iii. Eggs could be shipped in clean unused packaging.  
  DRAFT FOR PUBLIC CONSULTATION 
30 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.7.3.  S. arizonae serotypes 18:Z 4,Z32 and 18:Z 4,Z23. 
3.7.3.1.  Hazard identification 
 
3.7.3.1.1.  Aetiological agent 
S. arizonae  serotypes 18:Z 4,Z32 and 18:Z 4,Z23 are covered in this section. 
 
3.7.3.1.2.  OIE list 
Salmonella arizonae  is not included in the OIE list of notifiable diseases. 
 
3.7.3.1.3.  New Zealand status 
S. arizonae  is listed in the register  of unwanted organisms. 
 
3.7.3.1.4.  Epidemiology 
S. arizonae  is a recognised pathogen of turkeys (112) and Crespo et al. (108) reported 
epidemiological evidence that S. arizonae  is transmitted vertically in turkeys.  
 Silva et al. (113) reported naturally occurring disease in chic kens attributable to S. arizonae  
(18:Z
4,Z32). Birds showed signs of blindness, central nervous system disease, and death with 5 
percent of the birds affected. The ability of S. arizonae  to penetrate the shells of chicken eggs 
and infect embryos after dipping of eggs into broth cultures (114) and to infect chickens 
following either subcutaneous or oral i noculation (115) has been demonstrated.  
 
3.7.3.1.5.  Hazard identifica tion conclusion  
It is concluded that S. arizonae  is classified as a potential hazard in the commodity. 
 
3.7.3.2.  Risk assessment 
3.7.3.2.1.  Entry assessment 
In their report of ariz onosis in chickens, Silva et al. (113) noted that they had been unable to 
find earlier reports of S. arizonae  infection in that species. Searches by this author have failed 
to reveal any other reports. Literature searches have not identified reports of S. arizonae  being 
found in microbiological examinations of chicke n eggs or derived products. On the basis that 
only one report of S. arizonae  infection in chicken has been located and that being from Sao 
Paulo in 1980, it is concl uded that the likelihood of S. arizonae  infection in the commodity is 
very low.  The entry assessment is considered to be negligible.    
3.7.3.2.2.  Risk estimation 
Because the entry assessment is negligib le, the risk estimate is negligible and S. arizonae  is 
not classified as a hazard in the commodity.  Therefore, risk management measures are not 
justified. 
 DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 31 3.7.4. Salmonella Typhimurium DT 104 carrying resistance to several antibiotics. 
3.7.4.1.  Hazard identification 
 
3.7.4.1.1.  Aetiological agent 
This section considers S. Typhimurium DT104 carrying resistan ce to several antibiotics. Non-
multi-resistant strains of S. Typhimurium DT104 fall into th e same category as "other 
salmonellae" considered in section 3.7.6. Multi -resistant strains have  been of particular 
concern because of a global epidemic of such strains and the difficulties in treating infected 
humans.  
3.7.4.1.2.  New Zealand status 
S. Typhimurium DT104 is listed in the register of unwanted organisms. 
 S. Typhimurium DT104 is isolated from huma ns and non-human sources in New Zealand 
relatively infrequently. In his review , MacDiarmid (116) reported that S. Typhimurium 
DT104 had been isolated from seven non-human samples between 1997 and 2001 and that three of the isolates were multi-drug resistant. From 1992 to 2001, 37 of 39 isolates from 
human sources were multi-drug resistant. None of these isolates came from poultry or poultry 
environments. Strains carrying re sistance to several antibiotics are of particular concern to 
public health authorities.  
3.7.4.1.3.  Epidemiology 
Although multi-resistant S. Typhimurium DT104 (DT104) is of  prime concern in this risk 
analysis the epidemiology is similar to that of non-resistant strains. DT104 has a broad host 
range including cattle, sh eep, goats, pigs, poultry, humans, dogs , cats, horses, and a number of 
other species (117-120).   In Britain, the earliest reports of DT104 were from humans in the early 1960s (118-120). The 
first isolations of a multi-resistant strain were from a migratory gull and an imported parrot in 1984, with further isolations from imported exotic birds during 1985 and 1986 (121). These 
isolations were followed by an epidemic of  multi-resistant DT104 st rains involving cattle, 
sheep, pigs, poultry, and other species that peaked in cattle in 1995 (122) and has since 
declined (123). Cattle are considered to be  the principle reservoir host. The pattern of 
infections in humans has been similar to that  in cattle, with a peak in 1997 and a decline 
continuing until the latest data available, from 2004 (124).   During the 1990s an epidemic of multi-resistant S. Typhimurium affected many countries. In 
the Pacific Northwest of the United States the commencement of the epidemic, which affected 
cattle and humans, was recognised in 1990 (125), in parallel with that  in Great Britain. 
Threlfall (119) identified reports of human infections with multi-resistant S. Typhimurium 
DT104 through much of Europe, the Middle East, S outh Africa, Trinidad, and the Philippines. 
Data illustrating recent trends outside Great Britain has not  been located so the extent to 
which the epidemic is following the downward  trend evident in Great Britain is unknown. 
 DT104 has not been reported from poultry sour ces in either Australia or New Zealand. 
 Although infection of poultry (par ticularly turkeys but also ch ickens) with DT104 is widely 
recognised, its epidemiology in these species has not been well documented. It has been 
thought that some Salmonella  serotypes, especially S. Typhimurium, have very little host 
preference. This view is bei ng revised with the recognition th at genetic determinants are DRAFT FOR PUBLIC CONSULTATION 
32 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  contributing to substantial variations in the breadth of host range fo r many strains (117, 126, 
127). Even during the period following the recognition of the epidemic of DT104 this organism ranked lowly amongst Salmonella  isolates from poultr y and poultry-related 
environments in the USA (128, 129) and th e Netherlands (130). In the United Kingdom 
during 2004, routine monitoring of the Salmonella  status of commerci al poultry flocks 
revealed no DT104 infections in breedi ng flocks and only 3 percent of all Salmonella  isolates 
from broiler and layer flocks were identified as S. Typhimurium.  
 Establishment of infection in the intestinal tract and faecal excretion of DT104 by chickens 
(131, 132), and contamination of poultry shed en vironments (133) and feedstuffs (128) have 
been demonstrated.   Infection of eggs following experimental in fection of chickens with DT104 has been 
demonstrated (131). Leach et al. (134) found that contamination of eggs was more frequent 
when hens had been infected intranasally than when infected orally. The significance of this 
finding is uncertain as it is gene rally considered that the faecal -oral route of infection is the 
most common means of transmission of salmon ellae. Surveys, using samples of six boxed 
eggs, found prevalences of 0.01 percent in England and Wales in 1991, 0.04 percent in 
England in 1995/6 and nil from 4,753 samp les from throughout the UK in 2003 (135). Benson 
et al. (129) reported that 250,000 eggs, from th e north-eastern United States, had been 
examined for salmonellae with very few S. Typhimurium isolates and with none of them 
being DT104.   
3.7.4.1.4.  Hazard identifica tion conclusion  
On the basis that infection of eggs with DT104 is known to occur, and the ability of DT104 to 
cause disease in humans, it is concluded that S. typhimurium DT104 is classified as a 
potential hazard in the commodity.   
3.7.4.2.  Risk assessment 
3.7.4.2.1.  Entry assessment 
Although available evidence indicates that DT10 4 infection of eggs is rare, for reasons 
described above the entry assessment is  considered to be non-negligible. 
 
3.7.4.2.2.  Exposure assessment 
Although confirmatory evidence has not been sighted, the likelihood of infection of 
hatchlings from infected eggs is consider ed non-negligible. The exposure assessment is 
therefore considered to be non-negligible.  
3.7.4.2.3.  Consequence assessment 
The consequences of the introduction of DT104 w ith chickens hatched from imported eggs is 
likely to be limited to the commercial ope rations of importing companies so long as 
importations are into breeding establishments with hatchery systems meeting the standard 
required by the Poultry Industry Association of  New Zealand (Inc.) (3) and the Egg Producers 
Federation of New Zealand (Inc). These c odes of practice impose requirements for 
Salmonella  monitoring and control throughout the hi erarchy of breeding establishments. 
Costs arising from detection of DT104 in a gran dparent or parent breed ing hatchery would be 
considerable but limited to the company.  Importation of the commodity through channels other than  commercial operations and 
without the support of subsequent screening programmes under quarantine-like conditions 
carries a likelihood that DT104 c ould establish in non-commercia l poultry with the potential 
to lead to infection in  livestock and humans. DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 33  
Although some of the earliest re ports of multi-resistant strain s of DT104 came from wild 
birds and a parrot, the reservoir host is considered to be cattle. As a pathogen in wild birds, 
multi-resistant DT104 presents no greater hazard than the wide range of salmonellae already 
present in New Zealand. DT104 is not consider ed to be a hazard to the environment. 
 The consequence assessment is c onsidered to be non-negligible. 
 
3.7.4.2.4.  Risk estimation 
Because the entry, exposure, and consequen ce assessments are non-negligible, the risk 
estimate is non-negligible and DT104 is classified  as a hazard in the commodity.  Therefore, 
risk management measures can be justified.  
3.7.4.3.  Risk management 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  
i. The likelihood of eggs carrying DT104 could be greatly reduced by importing eggs from 
hatcheries with biosecurity systems in place to reduce the lik elihood of salmonellae 
entering, with routine surveillance to detect in fection.  For example, hatcheries could be 
required to demonstrate compliance with the standards documented in appendix 3.4.1 of 
the OIE Terrestrial Animal Health Code  (1) (or equivalent). 
 
ii. Birds in the laying flock could be tested to ensure that they do not carry infection and 
eggs could be imported only from flocks recognised by the appr opriate veterinary 
administration as being free of infection.  The OIE Manual  does not prescribe a test for 
international movement of animals or animal products although agent identification is listed as an “alternative test”
 suitable for the diagnosis of di sease within a local setting, 
and for use in the import/export of animals after bilateral agreem ent (34). There are 
numerous methods for isolation of Salmonella  in use world-wide a nd culture techniques 
using pre-enrichment, enrichment, or selec tive plating media are described by the OIE 
(34). 
 
iii. It could be required that eggs do not come in contact with fo mites that might be infected. 
 
 DRAFT FOR PUBLIC CONSULTATION 
34 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.7.5. Salmonella Enteritidis 
3.7.5.1.  Hazard identification  
 
3.7.5.1.1.  Aetiological agent 
Although only phage type 4, from amongst the range of S. Enteritidis phage types, is listed in 
the New Zealand register of unwanted organism s, this section covers  all phage types.  
  
3.7.5.1.2.  New Zealand status 
S. Enteritidis phage type 4 (PT4) is the second most common S. Enteritidis phage type 
isolated from humans in New Zealand with 128 isolates being reco rded between 2000 and 
2004 (116). A high proportion of human isolates co me from people with histories of recent 
international travel (136). Seven isolates have been recorded from non-human sources 
between 1990 and 2003 with none of those bei ng recorded from poultr y or poultry related 
sources (116, 136).   
3.7.5.1.3.  Epidemiology 
The earlier stages (1979 to 1987) of an internat ional pandemic of human disease attributed to 
Salmonella Enteritidis affecting North and South Am erica, Europe, and possibly southern 
Africa were described by Rodrigue et al. (137). Human cases were attributed to consumption 
of eggs or poultry from infect ed chickens. The decline in S. Enteritidis incidents in poultry 
followed introduction of control measures and codes of practice in the industry. This 
pandemic was associated with S. Enteritidis PT4 in Great Britain and continental Europe 
(138) or with PT13, PT8, and PT4 (in d eclining order) in North America (139).  
 The on-farm epidemiology of S. Enteritidis and the basis for the development of the pandemic 
have been reviewed by Guard-Petter (140). In  a retrospective view of the epidemic of 
S. Enteritidis, Rabsch et al. (141) hypothesised that the control of S. Gallinarum-Pullorum, 
which shares an immunodominant surface antigen with S. Enteritidis, during the mid-1900s, 
removed the protective effect of that organism and left an eco logical niche to be filled by 
S. Enteritidis. Mice are considered to be the likely reservoir for S. Enteritidis (142-144) and 
the decline in flock immunity following control of S. Gallinarum-Pullorum allowed 
widespread infection of poultry.  In her review, Guard-Petter (140)  generalises in saying that S. Enteritidis causes no clinical 
disease in chickens but has a unique characteris tic of infecting the e ggs of infected hens. 
Although these comments might not apply to all phage types of S. Enteritidis, they appear to 
be relevant to those that have  contributed to the pandemic of human disease originating from 
poultry. Infection is located both in the egg ( 145) and on the surface of shells (145-147). Eggs 
are considered to be the major source for human S. Enteritidis infections. Control of S. 
Enteritidis in hen houses is difficult because of the ability of the organism to survive in the 
environment and because of its ability to in fect other species, including mice, which can 
reintroduce the organism even afte r otherwise adequate cleaning. S. Enteritidis may infect 
eggs prior to shell formation and vertical tr ansmission to hatchlings  may occur (145). In a 
small proportion of birds, S. Enteritidis PT4 infection may be  maintained until birds enter lay 
(148).  The European Union Council Directive 92/117/ EEC requires that all countries have 
mandatory procedures in place to control Salmonella  infections in poultry breeding and 
production systems. In the UK, implementation of these procedures has been followed by DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 35 marked reductions in Salmonella  infections in poultry, espe cially in breeding hatcheries 
where there has been only one episode duri ng the years 2002 to 2004 (104, 124, 149), which 
was in an establishment producing eggs for pharmaceutical use. Comparable reports of the status in other EU countries or in th e United States have not been located. S. Enteritidis is 
reported in Australia but is not es tablished in the poultry industry. 
 
3.7.5.1.4.  Hazard identifica tion conclusion  
It is concluded that S. Enteritidis is classified as a potential hazard in the commodity. 
 
3.7.5.2.  Risk assessment 
3.7.5.2.1.  Entry assessment 
On the basis that S. Enteritidis may infect eggs, the entr y assessment is considered to be non-
negligible.  
3.7.5.2.2.  Exposure assessment 
Vertical transmission of S. Enteritidis has been demonstr ated. There is a non-negligible 
likelihood that hatchlings from infected eggs wi ll be infected and that  some hatchlings will 
excrete organisms contaminating the environmen t, thus leading to infection of others.  
 The exposure assessment is consid ered to be non-negligible. 
 
3.7.5.2.3.  Consequence assessment 
The consequences of the introduction of S. Enteritidis with chickens hatched from imported 
eggs is likely to be limited to the commercia l operations of importi ng companies so long as 
importations are into commercial breeding establishments with hatchery systems meeting the standard required by the Poultr y Industry Association of New Zealand (Inc.) (3) and the Egg 
Producers Federation of New Zealand (Inc). Thes e codes of practice impose requirements for 
Salmonella  monitoring and control throughout the hier archy of breeding establishments. The 
difficulty of eradicating S. Enteritidis from poultry sheds is su ch that costs of establishment of 
such infection in a grandparent or pare nt breeding hatchery would be high.  
 Importation of the commodity through channels other than  commercial operations and 
without the support of subsequent screening programmes under quarantine-like conditions 
carries a likelihood that S. Enteritidis could establish in non-commercial poultry, with the 
potential to lead to infection in livestock and humans. S. Enteritidis is not a hazard to the 
environment.  The consequence assessment is c onsidered to be non-negligible. 
 
3.7.5.2.4.  Risk estimation 
Because the entry, exposure, and consequen ce assessments are non-negligible, the risk 
estimate is non-negligible and S. Enteritidis is classified as  a hazard in the commodity.  
Therefore, risk management measures can be justified.  
3.7.5.3.  Risk management 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  
i. The likelihood of eggs carrying S. Enteritidis could be greatly reduced by importing eggs 
from hatcheries with biosecurity systems in place to reduce the likelihood of salmonellae DRAFT FOR PUBLIC CONSULTATION 
36 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  entering, with routine surveillance to detect in fection.  For example, hatcheries could be 
required to demonstrate compliance with the standards documented in appendix 3.4.1 of 
the OIE Terrestrial Animal Health Code  (1) (or equivalent). 
  
ii. Birds in the laying flock could be tested to ensure that they do not carry infection and 
eggs could be imported only from flocks recognised by the appr opriate veterinary 
administration as being free of infection.  The OIE Manual  does not prescribe a test for 
international movement of animals or animal products although agent identification is listed as an “alternative test”
 suitable for the diagnosis of di sease within a local setting, 
and for use in the import/export of animals after bilateral agreem ent (34). There are 
numerous methods for isolation of Salmonella  in use world-wide a nd culture techniques 
using pre-enrichment, enrichment, or selec tive plating media are described by the OIE 
(34).  In addition, indirect and compe titive ELISAs are described for serological 
diagnosis of S. Enteritidis infection, and the whole blood test for immunological 
diagnosis of S. Gallinarum-Pullorum may be used to detect S. Enteritidis  although the 
sensitivity of this test is low (34). 
 
iii. It could be required that eggs do not come in contact with fo mites that might be infected. 
  DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 37 3.7.6. Other salmonellae 
3.7.6.1.  Hazard identification 
 
3.7.6.1.1.  Aetiological agent 
The salmonellae addressed in this section are those serotypes and phage  types not covered in 
sections 3.7.1 to 3.7.5.   
3.7.6.1.2.  New Zealand Status 
In New Zealand, over the period 1999 to mid 2005, typing of Salmonella  isolates from 
humans yielded over 140 serotypes/phage type s (150-154). During the same period typing of 
isolates from animals, animal feeds and thei r environment yielded over 80 serotypes/phage 
types (150-153, 155). The frequency with which sp ecific types were isolated during each year 
varied greatly with many of the serotypes/ phage types being isolat ed from human or non-
human sources on only one occasion. Each year, three to five serovars or phage types not 
previously identified in New Zealand were repor ted. Most were from humans and most were 
from travellers or immigrants. With many Salmonella  infections being subclinical, the full 
range of serovars and phage types present in New Zealand and the extent of introductions to 
the country are unknown.   
3.7.6.1.3.  Epidemiology 
The epidemiology of different Salmonella  serotypes follows broadly similar patterns. Spread 
within and between susceptible species is main ly via the faecal-oral route, with organisms 
surviving for varying periods of time in differe nt environmental niches. Host specificity or 
host preference varies between Salmonella  serotypes and phage types.  
 Transovarial transmission requires that the or ganism infects the ovary  and/or oviduct (156). 
That such infections are restricted to only specific salmonellae was illustrated by artificial 
infection of chickens with six Salmonella  serovars, with S. Enteritidis being the only serovar 
resulting in infection of tissues of the reproductive tract (157). The Salmonella  serovars/DTs 
infecting the reproductive tracts of chickens a nd turkeys are highly host adapted and De Buck 
et al (156) observed that tropism for the reproductive tract is shown by S. Abortusequi and S. 
Abortusovis, both of which are highly host ad apted for horse and sheep respectively.  
 Vertical transmission resulting from contaminati on of the outside of eggs may occur but this 
route appears less common than the trans ovarial route although it may result from 
contamination by a wider range of Salmonella  serovars present in the environment. Infection 
of eggs with salmonellae on or through the shell is uncommon and most infection of chicks in 
hatcheries arises from environmental contamin ation following the hatching of infected eggs 
(158).  
3.7.6.1.4.  Hazard identifi cation conclusion 
As the commodity definition requires that eggs  be sanitised to OIE standards and that 
infection of the contents of clean dry eggs with  intact shells will arise only from host-adapted 
strains of salmonellae, the like lihood of infection by miscellane ous salmonellae is very low. 
Given the requirement of other biosecurity cons iderations that breeding establishments and 
hatcheries must comply with OIE standards, it  is concluded that “other salmonellae” are not 
classified as a potential hazard in the commodity. 
 DRAFT FOR PUBLIC CONSULTATION 
38 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND   
3.8. ORNITHOBACTERIUM RHINOTRACHEALE 
3.8.1. Hazard identification 
3.8.1.1.  Aetiological agent 
Ornithobacterium rhinotracheale  is a pleomorphic gram-nega tive rod which grows slowly on 
agar with 5 percent sheep blood in an  atmosphere of 5 to 10 percent CO 2 (159).  
 O. rhinotracheale was first identified in 1993. Subseque nt investigations showed that the 
bacterium had been present in Germany in tu rkeys since 1981 and rooks since 1983, and the 
organism had also been isolated in Belgiu m and the United States prior to 1990 (159).  
 Van Empel (159), quoting others, stated  that “It is quite possible that O. rhinotracheale  
infections in poultry prior to 1993 may have been  wrongly attributed to viruses or to other 
bacteria such as Pasteurella , Riemerella  etc.”  
 
3.8.1.2.  OIE list 
O. rhinotracheale  is not included in the OIE list of notifiable diseases. 
  
3.8.1.3.  New Zealand status 
O. rhinotracheale  is listed in the register of unwanted organisms 
 O. rhinotracheale  has not been identified in New Zealand. Diagnoses of both Pasteurella and 
Riemerella  infections in poultry in New Zeal and leave open the possibility that O. 
rhinotracheale  may be present (see comments by Va n Empel quoted above). Birds from an 
unknown number of flocks in New Zealand have been tested for O. rhinotracheale  using 
imported ELISA kits with negative results (Les With, Poultry Veterinary Services, quoted in 
reference (57)).  
3.8.1.4.  Epidemiology 
O. rhinotracheale  is widespread in poultry flocks in the absence of diseas e and it is doubtful 
if it should be regarded as a primary pathogen. Contribution to clinical disease is influenced 
by environmental and management factors, together  with the presence of other diseases or the 
involvement of secondary infections. In experime ntal infections of tu rkeys, prior infection 
with turkey rhinotracheitis virus or Newcas tle disease virus aggrav ated the effects of O. 
rhinotracheale . In broilers, Newcastle disease virus ha d a similar effect, while prior infection 
with infectious bronchitis vi rus and bacteria such as Bordetella avium  and E. coli  have 
successively lesser effects.   Surveys of poultry flocks in the north-central region of the United States (160), Turkey (161), 
and Brazil (162) have all shown high proportion s of flocks to be infected and prevalence 
within layer flocks to be in excess of 50 percen t. ELISAs have proven to be effective tools for 
survey purposes.  Disease incidents which have subseq uently been recognised as due to O. rhinotracheale  were 
observed in ducks in Hungary in 1987, broiler chickens in South Africa in 1991, and turkeys 
in Germany in 1991 and 1992. Subsequent invest igations of culture collections revealed DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 39 isolates from respiratory tracts of turkeys (1981) and three rooks ( Corvus frugilegus ) (1983) 
(168). O. rhinotracheale  is now recognised as present and contributing to disease in South 
Africa, throughout Europe, in North and South Am erica, and in Asia. When the disease was 
first diagnosed in chickens in Japan in 1999, testing of blood samples collected from 1997 to 
1999 confirmed that the organism had infected  approximately 13 percent of both meat and 
laying birds in at least six pr efectures during those years (169). In the north central United 
States serological testi ng showed infection to be present in  90 to 100 percent of layer flocks 
and 43 to 52 percent of younger birds (160). Sero prevalence in infected breeding flocks is 
high with between 65 percent and 95 percent of birds in infected flocks returning positive 
serology results (162, 170, 171).   Reports of O. rhinotracheale  isolations have been from Galliformes (partridge, pheasant, 
quail, chicken, turkey, guinea fowl), Struthioni formes (Ostrich), Anseriformes (duck, goose) 
and Passeriformes (rook) (159). Report s which confirm association between O. 
rhinotracheale  and disease, however, are re stricted to Galliformes. 
 No reports of O. rhinotracheale  in Australia have been located and Australia treats this 
organism as one of concern in the importation of birds. On that basis, it is considered that 
O. rhinotracheale  is not present, or r ecognised, in Australia. 
 Van Empel and others have reported that vertic al transmission (either through transovarial or 
through cloacal contamination of eggs) can occu r although contamination rates of egg shells 
and contents are very low (159, 163). These reports are supported by that of van Veen et al. 
(164) which provided experimental epidemiologi cal evidence of infection being transmitted 
from infected turkey hatchlings to SPF chicke ns in incubators. Furthe r evidence of vertical 
transmission is provided by El-G ohary (165), who reported that O. rhinotracheale  was 
recovered from chick embryos and one-day-old chicks sampled from hatcheries, where low 
hatchability and high mortality in newly ha tched chicks were being observed. Back et al.  
(166) were able to isolate O. rhinotracheale  from the ovaries and oviduct of turkey breeder 
hens when these birds were artificially infect ed by either the intranasal, intravenous, or 
intramuscular route and concluded that the possibility of egg transmission of this agent could 
not be ruled out.  Varga et al. (167), on the other hand , using 12 strains of O. rhinotracheale , were unable to 
isolate organisms from inoculated egg shells after 24 hours at 37°C or from inoculated eggs 
beyond 14 day post inoculation. These authors concluded that O. rhinotracheale  is not 
transmitted via eggs. 
 
3.8.1.5.  Hazard identification conclusion  
In the absence of confirmation that O. rhinotracheale  is present in New Zealand, and given 
the ability of the organism to cause disease, this  organism is classified as a potential hazard in 
the commodity.  
 
3.8.2. Risk assessment 
3.8.2.1.  Entry assessment 
Vertical transmission through transovarial or  cloacal contamination of eggs has been 
described and O. rhinotracheale  has been recovered from ch ick embryos and one-day-old 
chicks.  Therefore, although ther e is some conflict in reports as to whether eggs can carry DRAFT FOR PUBLIC CONSULTATION 
40 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  infection and whether vertical transmission can take place, on balance it is concluded that 
there is sufficient evidence to suggest a non-ne gligible likelihood that chicken eggs imported 
from countries where O. rhinotracheale  is present could be infected.  
  The entry assessment for O. rhinotracheale  in the commodity from Europe and North 
America is considered to be non-negligible.   The entry assessment for O. rhinotracheale  in the commodity from Australia is considered to 
be negligible.  
 
3.8.2.2.  Exposure assessment 
Reports indicate that infected eggs can result in  infected hatchlings and that the organism can 
be transmitted to other birds in contact.  The exposure assessment is consid ered to be non-negligible. 
 
3.8.2.3.  Consequence assessment 
Many infections with O. rhinotracheale  are subclinical but disease does occur in poultry, 
especially in chickens and turkeys. The seve rity of disease is affected by environmental 
conditions and by the presence of other diseases. In  some incidents disease can be severe with 
clinical signs of respir atory disease, production losses and mortalities.  
 Infection has not been reported from humans, so O. rhinotracheale does not pose a risk to 
human health.   O. rhinotracheale  has not been reported to cause dis ease in non-poultry species or in non-
avian hosts. Therefore, the organism does not pose a risk to New Zealand’s native fauna. 
 
As a result of the potential impact of O. rhinotracheale  on the poultry industry in 
New Zealand, the consequence assessment is considered to be non-negligible. 
 
3.8.2.4.  Risk estimation 
Because the entry assessment for eggs imported fr om Australia is negligible, the risk estimate 
is negligible and O. rhinotracheale  is not classified as a ha zard in the commodity imported 
from Australia.    For the commodity imported from countries othe r than Australia, sin ce the entry, exposure, 
and consequence assessments are non-negligible , the risk estimate is non-negligible and 
O. rhinotracheale  is classified as a hazard in the co mmodity.  Therefore, risk management 
measures can be justified.  
3.8.3. Risk management 
 
One or a combination of the following options c ould be considered in order to effectively 
manage the risk:  DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 41 i. Tools available for detection of infected floc ks and/or infected birds include the culture 
of swabs from the infraorbit al sinus or nasal cavity al though these can provide false 
negative results, especially when plates are overgrown with fast growing contaminants. 
 
ii. ELISAs could be used which cross-react with different serotypes to test parent flocks. 
Commercial ELISA kits are available in Eu rope.  Serum plate a gglutinations tests 
(SPAT) are also available which may be se rotype-specific, although these may have low 
(65 percent) sensitivity (163).   
 
Eggs to be imported from Europe, Canada or the United States could come only from 
flocks shown to be free of O. rhinotracheale  on the basis of serological testing of a 
sample of laying birds.  Testing 60 samples w ould detect a seropreval ence of at least 5% 
in a flock with 95% confidence.  A sample  size of 90 would be required to detect a 
seroprevalence of at least 5% in a flock with 99% confidence. 
 
iii. Given that infected flocks could be expect ed to have a seroprevalence of 50-95% (see 
3.8.1.4), a smaller sample size could be considered.  For example, 11 samples would enable detection of a seroprev alence of at least 25% in a flock with 95% confidence (16 
samples for 99% confidence), whereas 5 samp les would detect a seroprevalence of at 
least 50% with 95% confidence (7  samples for 99% confidence). 
 
iv. Eggs could be imported from Australia without sanitary measures for O. rhinotrcheale . DRAFT FOR PUBLIC CONSULTATION 
42 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  3.9. MYCOPLASMA IOWAE 
3.9.1. Hazard identification 
3.9.1.1.  Aetiological agent 
Mycoplasma spp. are micro-organisms in the class Mollicutes. They are susceptible to 
desiccation, heat, detergents, and disinfectants, but are resistant to antibiotics that act by 
disrupting cell wall synthesis.  
 
3.9.1.2.  OIE list 
M. iowae  is not included in the OIE list. 
 
3.9.1.3.  New Zealand status 
M. iowae  is listed in the register of unwanted organisms and has not been diagnosed in 
New Zealand.  
 
3.9.1.4.  Epidemiology 
The primary host of M. iowae  is thought to be turkeys a nd, although lateral transmission 
occurs, the main means of spread  are venereal and transovarial . Prevalence in age cohorts of 
turkeys remains low until after sexual matur ity when infection is spread venereally, 
particularly at the time of artificial insemination (172, 173) . Following administration of 
infected semen, the organism establishes infect ion in the oviduct and large numbers of eggs 
may become infected (173, 174). M. iowae  causes a range of clinical signs in turkeys, 
especially decreased egg hatchab ility (2 to 5 percent reduction) (172). There are differences in 
opinion as to the significance of M. iowae  as a pathogen, even to extent that differing views 
may be expressed by the same author. For ex ample Jordan in 1985 (174) and Bradbury in 
2001 (175) included M. iowae  as one of four economically important avian mycoplasmas, 
while in 1996 Al-Ankari and Bradbury (176) conc luded that “there is insufficient data to 
reach any conclusions about the ec onomic significance, if any, of M. iowae  infections in 
turkeys, or in chicks or chick embr yos”, and in 2004 Bradbury (pers. comm.6) commented “… 
we have never used PCR to look for this Mycoplasma ( M. iowae ) because it is no longer 
considered important enough to be of interest”.   Bradbury and Klevin (172) st ated that “isolation of M. iowae  from chickens is not 
uncommon” and experimental infection of chic k embryos and of recently hatched chickens 
has been demonstrated (177-179). The only repo rts of naturally occurring infection of 
chickens located by this author are th ose of Yoder and Hofstad (180), Bencina et al. (181), 
and Aly et al. (182). The report from Bencina et al. is clear that the chickens infected with M. 
iowae  were from a mixed age flock in which bird s were reared in close contact and several 
species of Mycoplasma  were present. Comparable information is less clear from the other 
reports but that of Yoder and Hofstad states  that isolation of up to three strains of 
Mycoplasma  from individual chickens was not unco mmon, suggesting that flock hygiene was 
poor. No reports of M. iowae  being isolated from natural in fections in housed chickens 
managed under good hygienic c onditions have been found. 
 
                                                
 
6 Bradbury, J.M. Personal communication to Bruce Simpson 23 July 2004. DRAFT FOR PUBLIC CONSULTATION 
 
MAF BIOSECURITY NEW ZEALAND  Draft risk analysis for chicken hatching eggs • 43 No reports of M. iowae in Australia have been located and Australia treats this organism as 
one of concern in the importa tion of turkeys. On that basis, it is considered that M. iowae  is 
not present in Australia. 
  
3.9.1.5.  Hazard identification conclusion  
It is concluded that  M. iowae is classified as a potential a hazard in the commodity imported 
from Europe or North America.  It is concluded that M. iowae  is not classified as a potential  hazard in the commodity imported 
from Australia.  
 
3.9.2. Risk assessment 
3.9.2.1.  Entry assessment 
M. iowae  is only likely to be present in eggs from unhoused, poorly managed chicken flocks 
exposed to other bird species and with multiple age groups in contact with one another. However, it is unlikely that M. iowae  would be present in eggs from well managed breeding 
flocks.  On that basis, the entry assessment for M. iowae  in the commodity is considered to be 
negligible. 
3.9.2.2.  Risk estimation 
Because the entry assessment is negligib le, the risk estimate is negligible and M. iowae  is not 
classified as a hazard in the commodity.  Th erefore, risk management measures are not 
justified.   DRAFT FOR PUBLIC CONSULTATION 
44 • Draft risk analysis for chi cken hatching eggs MAF BIOSECURITY NEW ZEALAND  4.   References 
 
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