1.
|
Introduction
|
| 1.1 |
Four internationally recognized experts on avian influenza were asked to
give their opinion on the Canadian Food Inspection Agency (CFIA) response to the outbreak
of H7N3 highly pathogenic avian influenza (HPAI) in the Fraser Valley, British Columbia
between March and June of 2004. In particular, the panel was asked to review the science
of the response, and how it compared to that of other countries experiencing outbreaks of HPAI
and to generally accepted international standards. They were asked to identify areas in
which the response was deficient or exceeded international standards, and make
recommendations that would assist the CFIA in responding to any future outbreak of
notifiable avian influenza (NAI), which includes outbreaks due to HPAI virus or any strain
of H5 or H7 serotype. |
| 1.2 |
The panel consisted of : |
| 1.2.1 |
Dr. Trevor M Ellis
Senior Veterinary Officer
Veterinary Laboratory Division
Agriculture, Fisheries and Conservation Department
Hong Kong SAR Government
303 Cheung Sha Wan Road, Kowloon,
Hong Kong SAR, China |
| 1.2.2 |
Dr. Armin Elbers (epidemiologist) & Dr. Guus Koch (virologist)
Dept. of Virology
Central Institute for Animal Disease Control
Lelystad, The Netherlands |
| 1.2.3 |
Dr. Ruth Manvell
Virology Department
Veterinary Laboratory Agency
Addlestone, Surrey, UK |
| 1.2.4 |
Dr. Dennis Senne, Microbiologist
Diagnostic Virology Laboratory
National Veterinary Services Laboratories
Ames, Iowa, USA |
| 1.3 |
The evaluation is based on the Comprehensive Report on the 2004 Outbreak of
High Pathogenicity Avian Influenza (H7N3) in the Fraser Valley of British Columbia, Canada
(June 30, 2004) prepared by Canadian Food Inspection Agency (CFIA) staff and also on
discussions with staff from CFIA and BCMAFF. |
| 1.4 |
The response by CFIA in the Fraser Valley H7N3 outbreak has been compared
to international standards including the OIE Terrestrial Animal Health Standards for Avian
Influenza; the Australian Veterinary Emergency Plan (Ausvetplan 2002 and 2004 versions)
for Highly Pathogenic Avian Influenza (HPAI) ; Contingency Manual for Avian Influenza from
Veterinary Epidemiology Unit, Instituto Zooprofilattico Sperimentale dell Venezie, Italy;
the AI Contingency Plan for the Netherlands and also to the experience in Hong Kong of
control of H5N1 HPAI outbreaks in 1997, 2001, 2002 and 2003, the H7N7 HPAI outbreak in The
Netherlands in 2003 and recent outbreaks of NAI in the United States of America. |
2.
|
Observations
|
| 2.1 |
Veterinary Infrastructure in Canada |
| 2.1.1 |
Canada has an effective veterinary infrastructure with appropriately
qualified veterinary and support staff, veterinary laboratory services at the federal,
provincial and veterinary college level and the required funding and legislative
authorities in place to respond to an outbreak of HPAI at an internationally recognized
standard. Legislation was in place to prevent introduction of animal diseases, control and
eliminate zoonoses and significant animal diseases, regulate importation of animal
products, require reporting of designated diseases, regulate animal feeds, regulate
slaughtering and inspection of animals and meat products, provide compensation for
destroyed animals and enforce penalties for non-compliance with the regulations relating
to the above legislation. |
| 2.2 |
Infrastructure in place during the Outbreak |
| 2.2.1 |
During the outbreak CFIA rapidly responded to set up Emergency Operation
Centres (EOC) as defined in the Canadian Foreign Animal Diseases Manual of Procedures and
the Highly Pathogenic Avian Influenza Strategy and they ensured adequate level of staffing
for EOCs, investigation, epidemiology and surveillance teams to efficiently manage this
major and locally extensive outbreak. There appears to have been very good cooperation
between CFIA, BCMAFF and other provincial and municipal authorities, USDA, private
industry veterinarians and poultry producer organizations during the outbreak. There was
active involvement of the federal, provincial and municipal health authorities to ensure
full workplace safety and biosecurity precautions were followed during the depopulation
and control activities and that adequate human surveillance was conducted as part of the
control programme. The latter activities were fully consistent with recent WHO guidelines
that evolved after the Dutch H7N7 HPAI outbreak and the Southeast Asian H5N1 HPAI outbreak
during which human cases occurred. |
| 2.2.2 |
Communications between all relevant parties and with the public during the
outbreak was managed well using all available technologies and this was facilitated by
co-location of provincial and CFIA emergency operations centre in the one building and
enhanced by the geographical information system and aerial mapping support from the City
of Abbotsford. The real time mapping of the outbreak was a very important tool in the
daily management of this outbreak and would have contributed substantially to the final
control and eradication of this outbreak. |
| 2.2.3 |
There was also important operational support in veterinary diagnostic
laboratory testing, veterinary epidemiology, poultry medicine and science provided by BCMAFF
to CFIA as well as the other support by BCMAFF in linking the emergency operations centre
with other provincial and municipal bodies and with the poultry industry. These linkages
would also have contributed substantially to the final control and eradication of the
outbreak. |
| 2.3. |
Disease Control Actions Taken |
| 2.3.1 |
The disease control actions taken were consistent with internationally
accepted principles for HPAI control and included rapid detection of infected flocks,
stopping spread by movement controls and rapid destruction of infected and high risk
contact flocks and effective containment of infective materials. After the initial
diagnosis of a HPAI infected premises, which was fully consistent with internationally
accepted definitions, the definitions of negative, presumptively infected and confirmed
infected premises for land based poultry and waterfowl were appropriate and this was shown
to be a suitable disease control tool for this outbreak. |
| 2.3.2 |
The pathotyping of the H7N3 virus from the first shed on the first infected
premise showed it was a LPAI on 2 March. It was not until after 9 March when the
pathotyping of the H7N3 isolate from the second shed showed it to be HPAI, and a H7 virus
was identified from a second infected premises on the 10 March and this was confirmed as HPAI
on 11 March that the Minister declared the avian influenza Control Area (CA) in the Fraser
Valley with strict movement controls. |
| 2.3.3 |
Although strict quarantine and good biosecurity procedures were being
exercised with the depopulation and disposal on premises 1 and careful testing of high
risk contacts was undertaken, with hindsight, the outcome may have been better if
declaration of the CA with strict movement controls had occurred sooner. The rationale for
an earlier declaration could have been the subtype of avian influenza involved, the
pattern of rapidly rising mortality over 2 days in shed 2 and rapid tests to identify
avian influenza antigen or genome (PCR) in tissues of affected birds from shed 2. |
| 2.3.4 |
From the report it appears that BCMAFF was able to conduct virus culture
and PCR testing for avian influenza viruses but did not have reagents to specifically
identify H sub-types. Further specific identification of the subtype of avian influenza
virus, even H5 and H7 subtypes, then had to be sent to NCFAD which may have led to some
additional time before considering suspect HPAI. |
| 2.3.5 |
Timely and efficient reporting of laboratory results was hindered by the
inadequacy of the data handling system available. Further delays in reporting results to
control staff in the Fraser Valley occurred because of the structure in place for
transmission of results. |
| 2.3.6 |
The surveillance system and surveillance protocols were appropriate and
consistent with international standards for a HPAI outbreak. The surveillance coverage for
all sectors was thorough, comprehensive and well controlled. The use of dead bird swabbing
and PCR testing was more effective on a large scale for early detection than live bird
testing and the system developed to cover the various sectors was effective. The use of
the enhanced flock surveillance programme on 60 live birds from each commercial flock in
the 3 km zone around infected premises in the CA would be expected to detect 5% prevalence
with a 95% level of confidence of H7N3 avian influenza, whether it was LPAI or HPAI. The
initial use of serological testing in active surveillance was changed to swabbing of dead,
sick or live birds with PCR testing which was found to be a more effective means for early
detection. |
| 2.3.7 |
The system of movement restrictions, procedures for destruction of infected
birds and for pre-emptive depopulation, the process for considering exemptions to
depopulation of special birds, disposal of infected birds and products, cleaning and
disinfection procedures were all consistent with internationally used procedures for avian
influenza. Discussions in Vancouver indicated that disposal of carcasses presented some
special problems in the Fraser Valley due to the high water table in most of the valley,
which limited the potential for on farm burial of carcasses and litter. |
| 2.3.8. |
The system for lifting of restrictions and allowing farms to be repopulated
was based on the internationally accepted minimum time interval of 21 days after
satisfactory cleaning and disinfection of the last infected premises. The dual system
used, with no testing being required if farms were left empty for 60 days after approved
cleaning and disinfection and weekly testing for 4 weeks if farms chose to restock before
60 days after approved cleaning and disinfection, was quite acceptable. |
3.
|
Recommendations
|
| Recommendations provided by the peer review panel included the
following: |
| 3.1 |
A separate agency should question non federal personnel involved in the
outbreak (eg industry, farmers, provincial staff) to obtain an independent report of the AI
outbreak. |
| 3.2 |
A surveillance strategy for AI in Canada should be developed. |
| 3.3 |
Undertake further epidemiological studies in support of the supposition
that the AI virus spread to the index farm from waterfowl, and identify how the virus
subsequently spread to other premises. |
| 3.4 |
Investigate possibility that if aerosol spread was thought to have
occurred, whether the method employed to kill infected poultry could have predisposed to
further spread. |
| 3.5 |
Emphasise to the poultry industry the importance of bio-security,
particularly in view of the integrated nature of the industry in British Columbia. |
| 3.6 |
Initiate a Control Area as soon as possible, following the identification
of an H7 subtype associated with rising poultry mortality. |
| 3.7 |
Improve speed of initial diagnosis (and therefore response) by providing
typing reagents to BCMAFF provincial laboratory. |
| 3.8 |
For the surveillance of wild birds, it is acceptable to use pools of fresh
faeces as an alternative to catching the birds. |
| 3.9 |
Develop the relevant IT capabilities to ensure more efficient management
and transmission of laboratory data and improve the use of disease data obtained during
the outbreak. |
4.
|
Conclusion
|
| 4.1 |
This developed into a very extensive outbreak after what initially appeared
as a H7 LPAI case despite a sound avian influenza response plan being in place and
professionally executed control operations. It would be useful to investigate why the
outbreak rapidly became as extensive as it did. This would allow additional measures to be
considered to lessen the consequences of a future HPAI outbreak. |
| 4.2 |
Overall, we consider the strengths have been in the existence of concise
and well documented response plans and the efficient operational procedures and
communication systems that were put in place. The availability of an existing GIS with the
ability to generate accurate and concise mapping of the outbreak on a daily basis was a
real feature and this must have greatly enhanced the outbreak management. There were also
strong linkages between CFIA and provincial organizations especially BCMAFF and these
quickly enhanced the investigational, laboratory and epidemiology capacity to deal with
the outbreak. |
| 4.3 |
The surveillance plan and protocols for the various industry sectors during
the outbreak were at the upper end of international standards and were thoroughly and
effectively executed. |
| 4.4 |
The management and careful assessment of the composting for disposal of
carcasses and litter was at an internationally high standard and demonstrated an effective
tool for disposal of avian influenza infected poultry in environments where burial or
incineration is difficult. |
| 4.5 |
Carcass disposal is considered one of today's biggest challenges in disease
control programs. Composting carcasses and manure is becoming more common and is an
effective method for inactivating AIV and is environmentally friendly. |
| 4.6 |
It is important to recognize that the NCFAD has developed the capability to
diagnose and characterize avian influenza viruses. This reflects well on the staff and
leadership at the NCFAD. This capability will greatly facilitate the early confirmation of
future infections of avian influenza (hopefully not HPAI) should they occur. |
| 4.7 |
Finally, an active surveillance program will likely be a requirement for
most poultry exporting countries in the near future. We would strongly encourage
development of a national surveillance program for Canada and secure the necessary funding
to support such a program. The use of passive surveillance alone may not be acceptable to
Canada's trading partners, especially after a report of HPAI. |
