The Simcoe Muskoka District Health Unit (SMDHU) has received notification from Public Health Ontario that a dead bird found in the Town of Bradford West Gwillimbury has tested positive for West Nile virus (WNv).
This is the first lab-confirmed evidence of WNv in Simcoe Muskoka in 2025. As of July 25, 2025, no confirmed mosquito pools or human cases of WNv have been reported this year.
West Nile virus circulates between birds and some species of mosquitoes. The virus can be transmitted to humans by a mosquito bite if the mosquito has first bitten an infected bird. The risk of contracting WNv from an infected mosquito is highest in late summer and the health unit recommends the following personal protection measures:
- Use an approved mosquito repellent, following the manufacturer’s instructions.
- Wear light-coloured clothing and cover up in areas where mosquitoes are present.
- Stay indoors when mosquitoes are most active – at dusk and dawn – when possible.
Although most people will not become sick if bitten by an infected mosquito, WNv can cause severe illness in some people. Symptoms of WNv include fever, muscle weakness, stiff neck, confusion, severe headache and a sudden sensitivity to light. In rare cases, the virus may cause serious illnesses of the brain. Anyone experiencing symptoms should seek medical advice.
The health unit continues its surveillance for the virus throughout Simcoe Muskoka.
Anyone with concerns about a sick or dead bird can contact the Canadian Wildlife Health Cooperative (CWHC) at 1-866-673-4781.
For more information about West Nile virus, visit smdhu.org/WNv.
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