Outbreak Investigation Report on Avian Influenza in British Columbia, 2014
4. Disease Control Actions
4.1. Response Infrastructure
4.1.1. The Role of the Canadian Food Inspection Agency
The AI virus is defined by the OIE as any "type A" avian influenza virus with high pathogenicity, as well as all H5 and H7 virus subtypes. HPAI and low pathogenicity avian influenza — subtypes H5 and H7AI are federally reportable in Canada under the Health of Animals Regulations. The CFIA is the lead agency whenever a reportable animal disease is detected. Supportive roles are provided by other federal, provincial and municipal agencies, veterinary associations, and producer organizations.
4.1.2. The CFIA's Foreign Animal Disease Plans
The CFIA has developed strategies and operational plans to deal with potential incursions of foreign animal and reportable diseases. The Foreign Animal Disease Emergency Support (FADES) plan is the framework of federal-provincial cooperative agreements specifying their roles and responsibilities during an animal disease emergency. The FADES plan also describes the incident management system used to manage this outbreak.
The NAI Hazard Specific Plan (NAI-HSP) forms part of the overall plan to deal specifically with an incursion of NAI; it supplies background information on the disease itself, as well as outlines the principles of disease control and eradication, premises disinfection, and surveillance. The emergency response structure and the procedures to implement these plans are set out in the CFIA Emergency Response Plan and the CFIA Animal Health Functional Plan (AHFP).
4.1.3. Emergency Operations Centres Established
When a high-risk specimen is submitted due to evidence of a federally-reportable disease, CFIA area and national emergency response teams are alerted. Once the diagnosis is confirmed, a sequence of events is activated that put in place the control and eradication procedures described in the NAI-HSP, the AHFP, and the CFIA Emergency Response Plan. A regional and/or area emergency operations centre (REOC/AEOC) is established to coordinate the field investigation and disease control activities. In addition, a national EOC (NEOC) is established at Headquarters in Ottawa to support the field activities.
4.1.4. Incident Command Post (ICP) and Joint Emergency Operations Centre (JEOC)
An ICP and the BC Coastal Region EOC were established at the Abbotsford Animal Health District Office on December 2nd, 2014. As outlined by the BC FADES plan, the provincial and federal operations were co-located.
The BCMAGRI-AHC is a member of the Canadian Animal Health Laboratory Network (CAHLN) network of accredited laboratories. This laboratory provides specialized expertise in diagnostic poultry pathology and is the foundation for early disease detection through passive surveillance. This local laboratory was utilized to support the outbreak surveillance capacity of the CFIA.
The BCMAGRI also provided support in veterinary epidemiology, surveillance, connections with industry representatives, GIS and mapping, and requirements for disposal methods.
4.1.5. National Emergency Operations Centre
On December 2nd, 2014, the NEOC was activated at the national level. The NEOC provides support to the field activities associated with disease control and eradication policy, legal issues, communications, consultations with national producer groups, international relations and inter-provincial liaison activities
4.2. Disease Control Zoning
4.2.1. Primary Control Zone
On December 8th, 2014, the Federal Minister of Agriculture declared a primary control zone (PCZ) to prevent the spread of NAI. The PCZ included almost half of the province's 944,735 square kilometers. Within the PCZ there were three disease control sub-zones around infected farms: infected zones (1 km); restricted zones (10 km); and security zones (remainder of the PCZ).
The NAI HSP, Appendix M, lists the requirements for movement of poultry, poultry products and related materials into, within, out of, and in-transit through the PCZ.
The PCZ was revoked on March 9th, 2015.
Figure 3 - Map showing the Primary Control Zone in the HPAI outbreak in BC, 2014
4.2.2. Zones within the Primary Control Zone
126.96.36.199 Infected Zones
Given the density of flocks in a small geographic area, control efforts were prioritized within 1 km of infected farms. In total, there were 150 commercial poultry farms in the infected zones, including all of those that were depopulated.
Because there was no evidence that the HPAI virus was being transmitted by localized spread early in the outbreak, stamping-out was applied without pre-emptive culling of flocks within 1 km around infected farms. Monitoring of tracing investigations, spatial pattern of spread was implemented in order to adjust this control measure and implement the depopulation of farms within the 1-km infected zone surrounding the IPs if necessary.
188.8.131.52 Restricted Zones
A Restricted Zone (RZ) of 10 km was established around each of the 11 infected commercial farms. The RZ contained 254 commercial poultry farms in a geographical area of 7057.8 hectares (70.6 square km).
An exception was made in the case of the infected non-commercial farm (IPNC-01). A Restricted Zone was deemed unnecessary because of the farm's low poultry density, as well as its geographical isolation from the industry in the Fraser Valley.
4.3. Epidemiological Tracing
In accordance with CFIA's NAI-HSP and the OIE's Terrestrial Animal Health Code (2014), the CFIA undertook movement tracing of all poultry, poultry products, and things exposed to poultry or poultry products associated with an infected premises during the 21-day period prior to the onset of clinical signs. This 21-day period, also known as the critical period, represents three times the maximum incubation period for avian influenza (7 days as cited by the OIE).
The purpose of this epidemiological tracing is to:
- Identify premises at risk of having been exposed to NAI virus by either direct or indirect contact with an infected farm; and
- Identify potential sources of introduction of NAI virus to infected premises.
The CFIA's Premises Investigation Questionnaire (PIQ) was used to collect relevant epidemiological data on investigated poultry farms. Within the critical period, all direct movements of poultry on and off an IP were investigated and evaluated. Trace-in and trace-out farms with no confirmed direct contact were subjected to a qualitative risk assessment to determine the potential for transmission by indirect contact. Indirect movements were classified as low, moderate, or high risk. Decisions concerning the traced premises were made by technical specialists and approved by the Planning Section Chief with input from the NEOC. As of February 20th 2015, 110 trace investigations were completed.
4.4. Laboratory Investigation
The CFIA's NCFAD in Winnipeg is the Canadian reference laboratory for NAI virus and is responsible for diagnostic work, monitoring test and reagent performance, developing new diagnostic assays and improving upon existing assays, and test validation. The CFIA also maintains a functional relationship with a network of accredited laboratories in each province (Canadian Animal Health Surveillance Network (CAHSN)) that perform testing for specific diseases such as NAI using common protocols and reagents.
The BCMAGRI-AHC in Abbotsford, BC is a CAHSN laboratory and conducted testing of all field samples for Matrix RRT-PCR for influenza A and RRT-PCR for H5. The NCFAD completed a suite of tests to confirm and characterize the virus, including: Matrix RRT-PCR, virus isolation in eggs, RRT-PCR H5, cELISA, bELISA, HI, IVPI, Histology, IHC, and sequencing. The majority of surveillance submissions were sent to the BCMAGRI-AHC. All 13 farms (11 commercial and two non-commercial) showing positive results were declared infected.
The NCFAD typed the virus as H5N2 in the first 12 cases and H5N1 in the last. Further sequencing and analysis indicated that the H5N2 infectious agent was a reassortant virus, which contained genes from Eurasian and North American lineages of avian influenza viruses. The virus contained gene segments from the highly pathogenic Eurasian H5N8 virus, including the H5 gene, and segments from typical North American viruses, including the N2 gene. This represents the first time a Eurasian HPAI H5 lineage virus has been a cause of outbreaks of avian influenza in domestic poultry in North America.
4.5. Movement Restrictions and Permitting
Initially, in order to control movements on infected premises (IP's), official quarantines were placed on farms within 1 km of an IP and farms with an epidemiological link to an IP. Permits were issued when movements were required on these sites. Once the PCZ was established on December 8th, movement was then controlled through general and specific permits. A total of 2324 movement permits were issued by the CFIA.
4.6.1. Baseline Surveillance
Blood samples and oropharyngeal swabs were collected once from live birds housed on farms located in the IZ and on epidemiologically-linked farms. The swab samples were tested using matrix RT-PCR for influenza A and RRT-PCR for H5. Serum was tested to detect antibodies to avian influenza.
- For commercial farms, an oropharyngeal swab was collected from 60 birds in each barn on the premises. Blood samples were collected from 20 birds per barn.
- For non-commercial premises, an oropharyngeal swab and a blood sample was collected from 25 birds, if the flock size was 25 birds or more. For flocks with fewer than 25 birds, the CFIA collected a sample from each bird. If domestic waterfowl, such as ducks and geese, were present on site, cloacal swabs were collected instead of oropharyngeal swabs.
4.6.2. Dead Bird surveillance
Commercial poultry farms within 10 km of IPs were placed under surveillance so any spread of the disease would be quickly detected. Dead birds were collected two times per week from farms in the IZ and once per week in the RZ. The CFIA and industry associations worked together to ensure producers met the outbreak surveillance requirements.
CFIA delivered bins to farms in the control zones with instructions on participation. Dead birds were left in the bins at the farm gates on days specified by CFIA. If there was no mortality on a given sampling day, the producer was to place a bin upside-down at the farm gate. The surveillance teams stayed at the property limits. The dead birds were left behind in the bins for disposal by the producer.
The compliance level varied throughout the investigation ranging from 30% initially and ending at over 95% in February. For those producers that appeared to be non-compliant, CFIA or an industry representative would follow up with the owners of these farms to determine the cause. This procedure ended on February 24th, 2015. A total of 8392 tests were completed at BCMAGRI-AHC for this activity.
4.6.3. Flock Health & Production Records
Data on production parameters such as mortality, egg production, water and feed consumption were sent by fax or email to CFIA twice per week from all farms located in the IZ, twice per week from commercial turkey and chicken broiler breeder operations located in the RZ, and once per week from all other commercial poultry farms located in the RZ.
4.6.4. Pre-movement Surveillance
For this specific outbreak, flock health records and negative dead bird surveillance results were considered as sensitive indicators for monitoring the presence of virus in the flock. The farms that had routinely participated in this outbreak surveillance program could have a specific permit issued based on this surveillance testing.
4.6.5. Provincial Passive Surveillance
Supplemental testing was provided by BCMAGRI-AHC who initiated NAI pre-screening of all owner-submitted avian diagnostic submissions to the laboratory during the outbreak period. Oropharyngeal and cloacal swabs were taken and rRT-PCR tested on submissions originating from commercial farms. Necropsy did not proceed until the test was confirmed NAI negative. It was this type of testing that detected NCIP-01.
4.7. Depopulation and Disposal Activities
All birds on infected farms were humanely euthanized by sealing the barns and flooding them with carbon dioxide (CO2) gas. A compost pile was built within the barns to inactivate the virus by heat treatment. The compost pile (inner and outer core) must meet or exceed 37°C for six consecutive days to ensure virus inactivation. CFIA disposal specialists recorded temperatures throughout the compost pile on a daily basis. When the temperature and time parameters were achieved, the compost pile was moved outside the barn for secondary composting.
4.8. Cleaning and Disinfection of Facilities and Equipment
Once the barns were empty, the CFIA conducted an on-site assessment with the owner of each premises. This assessment determined which buildings, equipment and materials required cleaning and disinfection and potential issues with difficult items and areas.
C&D was the responsibility of the premises owner, who was required to produce a protocol detailing how the farms would be cleaned and disinfected. The CFIA reviewed and accepted the protocols. The producer contacted CFIA after the cleaning was done and if this step was approved, disinfection could begin.
Approval of the cleaning by CFIA was based on a visual verification of the removal and disposal of all dirt and organic material from the surfaces to be disinfected, as well as the disposal of contaminated items that could not be disinfected. Disinfection consisted of spraying an approved disinfectant on all areas where birds would be present when the farm was repopulated, using sufficient quantity to meet the contact time specified by the manufacturer.
4.9. Release of Quarantine on Infected Premises
The release of quarantine for previously infected farms was allowed when one of the following conditions had been met:
- The CFIA approved the C&D procedures; and
- The farms completed a 21-day fallow period
The farm was then subject to the outbreak surveillance testing requirements of the zone in which it is located.
4.10. Release of Movement Restrictions on Non-Infected farms
Movement restrictions on non-infected farms ceased when the PCZ was rescinded. The exception was for those farms located within 1 km of infected farms that had not completed C&D at the time the PCZ was rescinded, in which case the movement restriction ended upon the removal of the official quarantine on the associated IP.
4.11. Three-Month Enhanced Surveillance
Due to the outbreak of NAI in the Fraser Valley, the routine surveillance program, CanNAISS, was temporarily suspended in BC on December 8th, 2014 while an intensive outbreak surveillance program was in place. Suspending routine surveillance activity also avoids the possibility of transmitting avian influenza via the sampling program itself. Enhanced post outbreak surveillance began on March 3rd, 2015, in BC, in order to demonstrate disease-free status. During the response to the NAI outbreak in BC, CanNAISS was ongoing in other parts of the country to demonstrate continued freedom from NAI and support exports of poultry and poultry products produced.
According to the OIE Terrestrial Animal Health Code (OIE, 2014: Article 10.4.3), NAI-free status can be regained three months following the cleaning and disinfection of the last IP, meaning the time period for the enhanced surveillance was March 3rd, 2015 to June 3rd, 2015.
Of the 848 poultry farms registered in the Province, 368 broiler farms and five hatcheries without birds were removed from the sampling plan, as surveillance normally targets older birds. 180 non-commercial farms were also removed from the sampling plan as they were not commercial poultry. This left 295 eligible farms for testing. 67 of these farms either had no birds on premises or the birds were too young. As a result, these farms were not available for test.
A total of 228 farms and 2,166 samples were tested with negative results for H5 and H7 avian influenza viruses, representing 91% of breeder farms, 84% of table eggs, ducks, geese or specialty chicken farms, and 49% of commercial turkey farms in the BC poultry industry.
After the three-month enhanced surveillance period, CanNAISS returned to normal activities in BC.
4.12. HPAI Freedom declaration
In accordance with the guidelines in the OIE Terrestrial Animal Health Code (2014), freedom from NAI was declared on June 3rd, 2015, three months following the approval of the last cleaning and disinfection. The Province of BC officially regained its NAI-free status and the OIE was notified on June 8th, 2015.
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