Christa Arsenault

Ontario Ministry of Agriculture and Rural Affairs, Guelph, ON.

AHL Newsletter 2020;24(3):4.

Canada has a comprehensive surveillance program in place for the early detection of foreign animal disease such as African Swine Fever (ASF) virus.  The newly launched CanSpot ASF surveillance pilot will enhance this surveillance with several tools in a phased approach.  The goal of ASF surveillance is to protect the Canadian commercial swine sector from the adverse effects of ASF on production and trade. The primary objective of surveillance in the domestic swine population is to enhance our ability to detect ASF rapidly should it enter Canada.  A secondary objective is to support the claim that the domestic pig population is NOT infected with ASF.

The first tool being launched as part of the pilot project is the “Risk-based early detection testing” with the goal to improve pathogen detection.  This pilot is similar to surveillance recently launched in the USA.  The pilot project is aimed at enhancing the diagnostic testing of ASF in Canada. The Canadian Animal Health Surveillance Network (CAHSN) laboratories will run routine diagnostic rule-out tests where ASF is NOT suspected.  Certain diseases/conditions may mask the clinical signs of ASF and delay detection.  Herds with a history of these diseases/conditions, or cases with a compatible clinical or pathological presentation are eligible for testing.

There is no change in the protocol for cases where ASF is suspected and these must be immediately reported to CFIA.

The CanSpot ASF will add other surveillance tools such as risk-based surveillance from abattoirs, increased veterinary presence and sampling on small-scale swine farms, and samples from wild pigs.

Both herd practitioners and pathologists can initiate this new ASF rule-out testing.  Any case submitted for pathology to the Animal Health Lab in Guelph may be tested for ASF if the following criteria are met:

• sufficient information to trace the animal (Premises ID or animal location); and
• appropriate tissues are submitted and include some or all of the following: whole blood, body fluids and sections of tonsil, spleen, kidney, lymph node and terminal ileum.

What happens if the rule-out testing (real-time PCR) is NEGATIVE?

• If the sample/animal is ASF-negative, the laboratory will report this result as per usual protocols.  The diagnostic test result will be included in the CanSpot ASF reporting (pilot period or annual reporting).
• No movement restrictions will be placed on the farm.

What happens if the rule-out testing (real-time PCR) is POSITIVE OR SUSPECT?

• The sample/animal yielded a positive or suspicious test result, but without further confirmatory testing and epidemiologic investigation, the true status of this case is UNKNOWN. This result could be a false positive result or a true case of ASF. The ASF PCR test is an excellent test so these results will be taken seriously.
• The approved laboratory will immediately inform the herd veterinarian and the local CFIA district office where the herd is located.  If the approved laboratory is conducting the test for another laboratory, they will immediately notify that laboratory and the original laboratory will be responsible for notifications.

• The local CFIA district office will:

check the health of the animals on the premises together with the herd veterinarian; may collect additional samples from pigs on the premises and coordinate collection and shipment of samples to the NCFAD in Winnipeg; and complete a risk assessment.  If the risk assessment finds no evidence of ASF, the CFIA will place a quarantine to stop movement of swine off the premises until the NCFAD confirmatory testing is completed (estimated 48 to 96 hours).  If the risk assessment finds a suspicion of ASF, the CFIA will place a quarantine to stop movement of swine, and may make a declaration of infected place to stop other traffic on and off the premises until the NCFAD confirmatory testing is completed (estimated 48 to 96 hrs.).

Clinicopathological presentations eligible for additional ASF testing at approved laboratories include:

1. Septicemia and/or multiorgan hemorrhage such as caused by E.rhusiopathiae; S.suis; S.

    zooepidemicus; A.suis; S.cholerasuis; other bacteria

2. Porcine Reproductive and Respiratory Syndrome virus (PRRS), especially when it causes

    cyanotic skin

3. Porcine Dermatitis and Nephropathy Syndrome (PDNS) and vasculitis that can be caused by

    PCV 2, PCV 3 or other pathogens

4. Hemorrhagic diarrhea / necrotizing enterocolitis such as caused by Salmonella spp;

    L.intracellularis; B. hyodysenteriae; B. hampsonii

5. Fibrinous pleuritis / pericarditis / hydropericardium such as caused by H. parasuis; S.suis

6. Mulberry heart disease

7. Splenic torsion

8. Abortion above historical trend for herd

9. Mortality above historical trend for herd

This pilot on risk-based early detection at approved laboratories is expected to run from July 2020 to June 2021.  Reporting and evaluation for the pilot will be completed at the 6 and 12-month time points.  Both the 6-and 12-month reports will be provided as part of an annual report for the CanSpot ASF program.

Initial reporting for stakeholders is anticipated to include the number of participating laboratories; the number of cases tested; summarized test results; and where possible, the number of eligible cases and the number of premises included in testing by province or region and time.

 

Reference

Canadian Food Inspection Agency. CanSpotASF technical description: Enhanced surveillance activities that aim to protect the commercial swine sector from the impacts of African Swine Fever. Ottawa, ON, 2020.