Ministry of Agriculture

In the decade since its initial North American detection in New York in 1999, West Nile Virus (WNV) has been reported throughout the United States and in most of the Canadian provinces.  WNV is transmitted primarily to wild birds by infected mosquitoes. Mosquitoes can also transmit WNV to humans, horses and occasionally to other animals. The first evidence of WNV infections acquired in British Columbia was reported in 2009. The table below reports the number of WNV cases and the number tested in BC based on WNV surveillance since 2009.

Summary of Annual Number of WNV Positive Indicators (& Number Tested¹ in BC by Species, 2007 to 2012

¹ A mosquito pool can contain up to 50 mosquitoes that are tested at one time. The number of horses tested is unknown.
Table data sources: Data from British Columbia Centre for Disease Control (BCCDC) annual WNV Surveillance Reports available at
http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/statsres/default.htm.

BC WNV surveillance results for the current year to date (and for years prior to 2009) are available at http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/Surveillance/

All positive results in all species have been located in the Okanagan, with the exception of one horse located in the Fraser Valley. Although variable across the province and from year to year, typically June to September is the risk period for WNV infection. Positive indicators have been detected in BC in the months of August and September.

Detection of WNV in crows and other corvids (ravens, crows, magpies, jays), which are very sensitive to the infection, is often used as an early warning of its presence in mosquitoes. Since April 2003, the Animal Health Centre has worked in close cooperation with the Canadian Wildlife Service of Environment Canada, the BC Ministry of Forests, Lands and Natural Resource Operations, the BC Ministry of Environment, the BC Centre for Disease Control (BCCDC) and the Regional Health Authorities to monitor for the presence of the WNV in dead corvid species. Information on dead bird reporting in BC, including online reporting by members of the public, is available at the following BCCDC website: (http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/Surveillance/WNvDeadBirdReporting.htm). In certain situations and areas, dead birds may also be tested.

Horses with WNV can exhibit a range of signs such as stumbling, confusion, listlessness, head pressing, lack of appetite, inability to stand, seizures and weakness. In severe cases (about 30%), horses that develop clinical signs will die or be euthanized. Although there is no specific treatment for the disease, there are vaccines to prevent WNV in horses. Horse owners should consult with their veterinarian about WNV vaccination, routinely drain standing water around homes and barns to reduce mosquito breeding sites, and use insecticides according to the label when needed. As a federal immediately notifiable disease, laboratories suspecting or diagnosing a horse with WNV are required to contact the Canadian Food Inspection Agency (CFIA).  The CFIA WNV case definition for horses can be accessed at http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/immediately-notifiable/west-nile-virus/surveillance/eng/1346131121021/1346131213336. For the purposes of provincial WNV surveillance, the Public Health Veterinarian at the Animal Health Centre collects information on horses with WNV and submits this information to the BCCDC for inclusion in the annual WNV Surveillance Reports:
(http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/statsres/default.htm).

The form for reporting horses with WNV can be accessed by clicking here.

BC veterinarians are encouraged to complete and fax this form to (604) 556-3010. Upon receipt of the completed form, the Public Health Veterinarian will follow-up with the submitting veterinarian.

BC Centre for Disease Control - West Nile Virus information page:
http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/default.htm

Canadian Food Inspection Agency West Nile Virus information page:   http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/immediately-notifiable/west-nile-virus/eng/1305840783267/1305840912854

Canadian Cooperative Wildlife Health Centre West Nile Virus information page: http://www.ccwhc.ca/west_nile_virus.php

BC Ministries of Environment and Forests, Lands and Natural Resource Operations: http://www.env.gov.bc.ca/wld/wldhealth/

The British Columbia Interagency Wild Bird Mortality Investigation Protocols & the 2012 Avian Influenza and West Nile Virus Surveys: (here is a link to the document http://www.bccdc.ca/NR/rdonlyres/4158EACF-8CF5-493E-A19E-AB2EF6A99885/0/AI_1pager2012.pdf) 

BC Ministry of Health West Nile Virus information page:
http://www.health.gov.bc.ca/pho/wnv.html

Funding to assist West Nile Virus BC Program Planning:
http://www.ubcm.ca/EN/main/funding/community-safety/west-nile-risk-reduction.html

Health Canada West Nile Virus information page:
http://www.hc-sc.gc.ca/hc-ps/dc-ma/wnv-vno-eng.php

Public Health Agency of Canada  - Canadian West Nile Virus Surveillance Information:
http://www.phac-aspc.gc.ca/wnv-vwn/index-eng.php

US Centre for Disease Control and Prevention West Nile Virus information page:  http://www.cdc.gov/ncidod/dvbid/westnile/index.htm