Chronic Wasting Disease

Overview

Background

Chronic wasting disease (CWD) is a disease of the brain of deer, elk and moose which is similar to BSE (mad cow disease) in cattle and scrapie in sheep. It was introduced into farmed elk in Saskatchewan from infected elk imported from the US in the late 1980s, and has since spread to wild white-tailed deer, mule deer and elk populations in several locations within Saskatchewan and Alberta. The disease is caused by infectious proteins, called prions, which can be transmitted by animal-to-animal contact or by contact with environments contaminated with these infectious agents. Infected animals become weak and emaciated and tend to drink large amounts of water and salivate excessively. CWD is invariably fatal and could have severe impacts of deer populations throughout North America. It appears unlikely the disease can be transmitted to humans and most domestic animals but the full host range of CWD is unknown.

WHAT THE CWHC IS DOING

Beginning in 1997, the Saskatchewan Ministry of Environment (MOE) and the CWHC started a CWD surveillance program for wild deer, elk and moose. This surveillance program was based primarily on the testing of hunter-killed animals and to a lesser extent on the testing of sick or dead cervids. The program ended in 2012 with over 45 000 heads tested and a total of 387 positives from 20 Wildlife Management Zones (WMZs) (see map). The CWHC continues to test cervids that are submitted through our diagnostic program and we have continued to diagnose CWD in new areas.

Starting in 2006 the CWHC embarked on a research program in Saskatchewan with the aid of PrioNet and the MOE to look at factors affecting the spread of CWD. Phase I of the project focused on direct and indirect contact rates, habitat selection, long distance movements and survival trends as they relate to CWD. Phase II which began in 2009 focused on direct observations of mule deer and their use of environmental sites to determine risk of infection by CWD.

LINKS TO SUBMISSION INFORMATION

Alberta

British Columbia

Saskatchewan

Testing Results

Year	Mule Deer	White-Tailed Deer	Elk	Moose	Total
Pos	Neg	Pos	Neg	Pos	Neg	Pos	Neg	Pos	Neg
1997¹	0	3	0	36	0	0	0	0	0	39
1998¹	0	91	0	18	0	2	0	0	0	111
1999¹	0	79	0	57	0	44	0	0	0	180
2000¹	1	184	0	726	0	89	0	0	1	999
2001 Spring¹	1	154	0	58	0	0	0	0	1	212
2001 Fall	0	1077	0	2236	0	340	0	0	0	3653
2002 Spring	1	134	0	24	0	0	0	0	1	158
2002 Fall	7	3244	2	2413	0	163	0	0	9	5820
2003 Fall	22	2830	0	1922	0	153	0	0	22	4905
2004 Fall	30	5265	2	1439	0	9	0	0	32	6713
2005 Fall²	25	2635	10	938	0	47	0	4	35	3624
2006 Fall²	27	2343	22	1497	0	164	0	10	49	4014
2007 Fall²	32	2561	13	1729	2	90	0	4	47	4384
2008 Fall²	43	3668	5	828	1	214	0	27	49	4737
2009 Fall²	34	2219	3	378	0	71	0	20	37	2688
2010 Fall²	31	792	4	552	0	51	0	18	35	1413
2011 Fall²	27	401	5	419	1	52	0	19	33	891
2012 Fall²	26	247	7	209	3	36	0	14	36	506
2013³	13	4	0	21	0	2	0	8	13	35
2014³	13	17	6	17	2	4	0	7	21	45
2015	21	87	5	95	0	15	1	24	27	221
2016	33	140	14	162	2	20	0	25	49	347
TOTAL	387	28175	98	15774	11	1566	1	180	497	45695

Notes:

This table does not include those specimens which were deemed unsuitable for testing.

¹From 1997 until the fall of 2000, only the brain section (obex) was used to diagnosis CWD. Starting in 2001, tonsils and/or retropharyngeal lymph nodes were also examined.

²Starting in the fall of 2005 animals under 1 year of age were no longer tested under the program because detectable infection is rare in a young animal and therefore not cost effective in terms of surveillance.

³The hunter surveillance program was discontinued in 2012 and the 2013 and 2014 numbers are from diagnostic samples.

Map

(Click to see the full sized image)