Outbreak Investigation Report on H5N2 Avian Influenza in Ontario, 2015
4. Disease Control Actions
4.1 Response Infrastructure
4.1.1 The Role of the Canadian Food Inspection Agency
Notifiable avian influenza (NAI) virus is defined by the WOAH as any "type A" avian influenza virus with high pathogenicity, as well as all H5 and H7 virus subtypes. NAI is a federally reportable disease in Canada under the Health of Animals Act. 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 Notifiable Avian Influenza 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. At the discretion of the Area Director General, 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 Area Emergency Operations Centre
The CFIA AEOC was activated on April 6, 2015, with the sections mobilizing in London, Ontario and Guelph, Ontario.
Support was provided by OMAFRA, who assisted with technical support and expertise, and who maintained a liaison role with CFIA throughout the response. Some OMAFRA staff were also embedded into the ICS structure as required. Additional support was provided by the FBCC who helped coordination with the poultry industry and provided industry specific knowledge and support as needed.
4.1.5 National Emergency Operations Centre
On April 6, 2015, the NEOC was activated in Ottawa. 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 Establishment of Zones
In accordance with CFIA's NAI-HSP, all farms within 10 km containing susceptible species were placed under quarantine. Due to the close proximity between IP2 and IP3, all susceptible farms within 10 km of one were also within 10 km of the other, so a combined zone was created. For clarity, these zones were identified as Avian Influenza Control Zone (AICZ) 1 which surrounded IP1 and AICZ 2, surrounding IP2 and IP3.
4.3 Epidemiological Tracing
In accordance with CFIA's NAI-HSP and the WOAH'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 of NAI. 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 WOAH). The date of an IP's first clinical signs was determined by examining production records and interviewing producers.
Based on information received from the laboratory indicating a high degree of homology between the 2015 Ontario NAI strain and the 2014 BC NAI strain, a decision was made in Ontario to shorten the incubation period from seven days to five. Even with this shorter incubation period, the 21-day critical period was maintained in response to this outbreak.
The purpose of epidemiological tracing is to:
- Identify premises at risk of having been exposed to NAI virus by either direct or indirect contact with an infected premises; 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, considering the stage in the outbreak and level of risk. Trace-in (onto premises) and trace-out (off of premises) farms with no confirmed direct contact were subjected to a qualitative risk assessment to determine the potential for transmission by indirect contact. This indirect movement was classified as low, moderate, or high risk. Decisions concerning the traced premises were made by the Planning Chief with input from the National, and Area Planning Sections.
As of July 22nd, 2015, 26 traces were identified and completed. Of the 26 identified traces, three were related to movement of live birds, eight were related to service providers having contact with birds; seven were related to movements of products/by-products and eight were related to service providers having no contacts with birds.
4.4 Laboratory Investigation
The AHL (Animal Health Lab) in Guelph, ON is a Canadian Animal Health Surveillance Network (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 sample submissions were sent to the AHL in Guelph. All three premises showing positive results were declared infected premises.
The NCFAD typed the virus as H5N2. Further sequencing and analysis indicated that the 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 Licensing
In order to control movement, a quarantine was placed on every location within the control zones, and on the additional high-risk premises identified earlier in this document.
To control movements on IPs, premises within 5 km of an IP and premises with an epidemiological link were initially quarantined and declared Infected Places. Licences were issued when movements were required on these sites. Once the NAI control zones were established, quarantines and declarations of infected places remained for the premises within 5 km and additional quarantines were placed on premises within 10 km. Movement was then controlled through licensing. The issuance of licenses was controlled by the Permit and Movement Control section and was largely based on participation in Dead Bird Surveillance (DBS) and flock health reporting, among other conditions. Industry coordinated the placement of birds on premises located between 5 and 10 km. As the outbreak progressed, permit conditions became less strict. During the response, a total of 532 movement licenses were issued by the CFIA.
4.6.1 Baseline Surveillance
Oropharyngeal swabs were collected once from live birds housed on premises located in the control zones, and on epidemiologically-linked premises. The swab samples were tested using matrix RT-PCR for influenza A and RRT-PCR for H5.
- For commercial premises, an oropharyngeal swab was collected from 60 birds in each barn on the premises.
- For non-commercial premises, an oropharyngeal swab 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 AICZ 1 and 2 were placed under surveillance so any spread of the disease would be quickly detected. Dead birds were collected twice per week from premises in AICZ 1 and 2 until May 21st, when it was reduced to once per week. The CFIA and industry associations worked together to ensure that producers met surveillance requirements.
CFIA delivered bins to farms in the control zones with instructions on how to participate in the surveillance program. Up to five recently-dead birds per barn on each premises were to be left for sampling in the bins at the farm gates. The sampling happened on a specific day or days each week, as determined by the CFIA. If there was no mortality on a given sampling day, the producer was to place a bin upside-down at the farm gate. This procedure was intended to limit the spread of the virus; the surveillance teams stayed at the property limits, never entering the premises. Once sampled, the dead birds were left behind in the bins for disposal by the producer.
Each day, a list of farms where dead birds were to be collected was developed by the Surveillance Unit. When bins were absent from the farm gate on the designated day, the producer was considered to be non-compliant. Compliance level overall was extremely high. For those producers that appeared to be non-compliant, CFIA or an industry representative would follow up to determine the cause. In addition to commercial poultry flocks, non-commercial backyard flocks were put under surveillance. These flocks were identified by themselves, by industry, or were found during surveillance activities. There was no way to accurately determine the percentage of small flocks identified out of the total community in the AICZ. Dead bird surveillance bins were supplied to these flocks with instructions on how to present the birds. Due to low volume of mortality expected, instead of being given specific days for pick up, small flock owners were instructed to call for sampling any time they had a dead bird.
DBS ended on July 13th for AICZ 1 and July 27th for AICZ 2. A total of approximately 1300 birds of all flock types were tested at AHL, and all samples were negative.
4.6.3 Flock Health & Production Records
Data on production statistics such as mortality, egg production, water and feed consumption were sent by fax or email to CFIA twice per week from all premises located in the AICZs, including small flock owners. When DBS dropped to once weekly from twice weekly, so did requirements for flock health questionnaires.
4.6.4 Pre-movement Surveillance
This surveillance was applied on poultry premises in the AICZ moving live poultry or poultry products. 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 premises that had routinely participated in this outbreak surveillance program were eligible for a license.
4.7 Depopulation and Disposal Activities
All birds on infected premises were humanely euthanized by sealing the barns and flooding them with carbon dioxide (CO2) gas. Compost piles were built inside the barns to inactivate the virus via Biological Heat Treatment (BHT) process. The CFIA protocol for this process requires the lower confidence interval of average temperatures in the inner and outer core of the compost pile to be greater than or equal to 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. Established CFIA protocols guided in-barn BHT and out-of-barn secondary composting. Secondary composting was the responsibility of the owner and did not require CFIA monitoring, and was conducted with the support and guidance of OMAFRA personnel to ensure compliance with applicable provincial legislation.
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.
Cleaning and disinfection (C&D) was the responsibility of the premises owner, who had to produce a protocol detailing how the premises would be cleaned and disinfected. The CFIA reviewed and accepted the protocols that included all the necessary information and considerations as per the site assessment. The producer contacted CFIA once the cleaning was done and if this step was approved, disinfection could begin.
Approval of the cleaning was provided by CFIA inspectors. It was based on a visual verification of the removal and appropriate 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. This step consisted of using detergent or degreasing agents to remove the virus and to expose any residual virus to disinfectant.
Disinfection consisted of spraying an approved disinfectant on all areas where animals would be present when the farm was repopulated, using sufficient quantity to meet the contact time specified by the manufacturer. Disinfection was also verified by CFIA inspectors prior to final approval.
4.9 Release of Quarantine on Infected Premises
The release of quarantine for previously infected premises was allowed under the following conditions:
- The CFIA approved the C&D procedures; and
- The premises:
- remained vacant of susceptible species for a minimum of 21 days following the approval of the C&D to ensure that any residual virus had been eliminated, or
- was restocked, and a weekly statistically valid testing by matrix PCR for the presence of the influenza type A was negative for the placed birds. The last test was conducted at least 21 days after the birds are placed in the barn.
All three previously infected premises chose option 'a'.
4.10 Release of Movement Restrictions on Non-Infected Premises
Movement restrictions on non-infected premises were released once the declaration of infected place was removed from the infected premises with which the non-infected premises were linked.
4.11 Post-Outbreak Surveillance
Following the approval of C&D on the last Infected Premises, the three-month Post-Outbreak Surveillance period was initiated. In order to meet WOAH criteria, an epidemiologically-sufficient sample was determined to be 160 farms from the outbreak area, in addition to the normal sampling of the province using the CanNAISS program. All samples were collected by private poultry practitioners under contract with CFIA and sent to the CFIA NCFAD for analysis.
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