Chapter 13 – Chronic Wasting Disease Voluntary Herd Certification Program
13.6 Appendix 6: Directive on CWD VHCP Laboratory-Related updates

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59 Camelot Drive
Ottawa, Ontario K1A 0Y9

TAHD-DSAT-DCAW-2011-11-01

October 20, 2011

Memorandum to: Network Laboratories and Regional Administrators and Status Assessors for the Chronic Wasting Disease Voluntary Herd Certification Program (CWD VHCP)

Subject: Update to clarify current samples collected, diagnostic test used, reporting, and approved laboratories on the CWD VHCP.

Background

Since the CWD VHCP was established in 2002, there have been many developments, including updates to the samples collected, the diagnostic screening test used, and approved laboratories on this program.

This directive provides a summary to all parties of the laboratory changes that should be in place since the release of the original national standards, to ensure that all procedures and reporting reflect the current sampling and testing, and submission to the appropriate laboratory. These changes are reflected in the CWD VHCP Module 13 of the Accredited Veterinarian's Manual.

Effective Date: Immediately
Both the obex and the retropharyngeal lymph nodes (RPLN) must be submitted for all farmed cervids tested for CWD.

The primary target tissue tested for all members of the family Cervidae (with the exception of members of the genus Odocoileus), such as elk, red deer, reindeer, sika deer, and fallow deer, is the obex of the medulla.

The primary target tissue tested for Odocoileus species (including white-tailed deer and mule deer) is the RPLN.

The additional submitted tissues will be frozen and held by the laboratory until the initial test is completed.

The standard screening test for the CWD VHCP is currently the Bio-Rad ELISA, and reporting should reflect this.

Effective immediately, please ensure that the results of analysis for CWD are reported as follows.

Results of Analysis on Samples Submitted for CWD via Bio-Rad ELISA Testing

Tested: CWD not detected
(Where the specimen submitted contained the correct target tissue for the species being tested.)

The sample should be reported as follows: "Bio-Rad ELISA was negative for disease specific PrP (PrPCWD). Based on the tissue available for testing, this animal was unlikely to have died from CWD."

Tested: CWD not detected in secondary target tissue
(Where the specimen submitted did not contain the primary target tissue identified for the species being tested.)

The sample should be reported as follows: "Bio-Rad ELISA was negative for disease specific PrP (PrPCWD). Based on the tissue available for testing, this animal was unlikely to have died from CWD."

This may include the following:

  • samples from white-tailed and mule deer where the RPLN was not submitted but obex and/or brain is available for testing;
  • samples from elk where the obex was not submitted but the RPLN or another area of the brain is available for testing

Submitted: Unsuitable for testing
(Where the specimen submitted did not have identifiable brain or RPLN tissue available for testing, and a report for analysis is completed.)

The sample should be reported as "Submitted: Unsuitable for testing." This should be followed with an explanation as to the cause for this result.

This may include the following:

  • samples where tissues other than brain/obex or RPLN are received;
  • samples where a skull/head is submitted but no testable tissues are present.

Note: For the purposes of testing under the CWD VHCP, all samples being reported as "Tested: CWD not detected" and "Tested: CWD not detected in secondary target tissue" will be considered as "tested" when the herd is assessed for advancement within the program.

The following are the network laboratories currently approved by CFIA for CWD testing using Bio-Rad ELISA.

Note: The term "Recognized laboratories" has been changed to "CFIA approved laboratories."

Agri-Food Laboratories Branch
TSE Laboratory
6909 – 116th Street
Edmonton, Alberta  T6H 4P2

Animal Health Laboratory
Laboratory Services (University of Guelph)
Ontario Veterinary College
Building 49, Box 3612
Guelph, Ontario  N1H 6R8

Manitoba Agriculture, Food and Rural Initiatives
Veterinary Services Branch
Veterinary Diagnostic Services
545 University Crescent
Winnipeg, Manitoba  R3T 5S6

Ministère de l'Agriculture des Pêcheries et de l'Alimentation du Québec (MAPAQ)
(French only)
Laboratoire d'epidemiosurveillance animale du Québec
3220 Sicotte Street
Saint-Hyacinthe, Quebec  J2S 7X9

Prairie Diagnostic Services
Room 2604, Diagnostic Immunology Laboratory
52 Campus Drive
Saskatoon, Saskatchewan  S7N 5B4

This directive will remain in effect until the CWD VHCP National Standards are updated to reflect these changes, or until it is superseded by another directive.

If you or your staff members have any concerns or questions, please contact Dr. Amanda Amaratunga or Dr. Aru Balachandran to discuss.

Sincerely,

Dr. Penny Greenwood
National Manager
Disease Control and Animal Welfare
Terrestrial Animal Health Division

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