Overview
Background
West Nile Virus (WNV) is a Flavivirus that can infect and cause disease in people, birds, horses, and many other animals. It is transmitted by the bites of infected mosquitoes (at least 50 species worldwide). The virus multiplies in the tissues of infected birds, circulates in the blood, and may be picked up by mosquitoes taking blood meals from these birds. These infected mosquitoes may then transmit the virus when they fly to another bird or animal and feed again. Although wild birds are the usual host animals infected by WNV, the virus also may infect amphibians, domestic poultry, domestic mammals (particularly horses), humans, apes, and monkeys. Please visit the Public Health Agency of Canada website for human disease information.
WHAT THE CWHC IS DOING
The CWHC coordinated a massive national surveillance project to monitor WNV in birds across Canada from 2001 until 2012. Since then, monitoring has continued as part of our ongoing surveillance efforts, with approximately 300 birds per year being tested for WNV since 2009. The CWHC works with governmental agencies and other organizations, such as the World Organization for Animal Health (OIE) to report occurrence of WNV in a timely fashion.
Testing Results
SUMMARY BY PROVINCE 2025
Numbers correct as of February 27, 2026
Select year:
| Province | Examined | Tested | Positive | Negative |
|---|---|---|---|---|
| British Columbia | 1 | 0 | 0 | 0 |
| Alberta | 7 | 2 | 0 | 2 |
| Saskatchewan | 723 | 368 | 114 | 250 |
| Manitoba | 75 | 75 | 30 | 45 |
| Ontario | 1168 | 229 | 113 | 116 |
| Québec | 801 | 160 | 107 | 45 |
| New Brunswick | 90 | 0 | 0 | 0 |
| Nova Scotia | 301 | 0 | 0 | 0 |
| Prince Edward Island | 80 | 0 | 0 | 0 |
| Newfoundland and Labrador | 5 | 0 | 0 | 0 |
| Yukon | 34 | 0 | 0 | 0 |
| Northwest Territories | 84 | 0 | 0 | 0 |
| Nunavut | 2 | 0 | 0 | 0 |
| TOTAL | 3370 | 834 | 364 | 458 |
*Manitoba numbers are supplied from Manitoba Agriculture, Food and Rural Development
Links
Provincial Information
Alberta Health and Wellness - West Nile Virus Information
British Columbia Ministry of Health - West Nile Virus Information
Manitoba Health - West Nile Virus Information
New Brunswick Health - West Nile Virus Information
Newfoundland and Labrador - West Nile Virus Information
Northwest Territories Health and Social Services - West Nile Virus Information
Nova Scotia Health and Wellness - West Nile Virus Information
Ontario Health and Long-Term Care - West Nile Virus Information
P.E.I. Health and Wellness - West Nile Virus Information
Quebec Santé et Services Sociaux - Virus du Nil occidental
Saskatchewan Ministry of Health - West Nile Virus information
Other Sites
Public Health Agency of Canada
Reports
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