Grey Bruce Public Health has received confirmation that an American crow, found deceased in Bruce County, has tested positive for the mosquito-borne West Nile Virus.

The crow was submitted to the Canadian Wildlife Health Co-operative for testing on June 6, 2025.

This positive test is a reminder that West Nile Virus (WNV) can be found in Grey-Bruce and of the importance of protecting yourself and family members from mosquito bites.

“While the risk of acquiring West Nile Virus in Grey-Bruce remains low, there are simple and effective steps people can take to prevent it,” says Senior Public Health Manager Andrew Barton.

“The best way to prevent West Nile Virus is to protect yourself from mosquito bites, such as by using insect repellent containing DEET or Incaridin and covering exposed skin while outdoors, particularly at dusk and dawn when mosquitoes are most active.”

This is the first bird to test positive for WNV in Grey-Bruce in 2025.

No human cases of WNV have been reported in Ontario so far this year. In 2023, 61 people – equivalent to a rate of 0.4 cases per 100,000 people – tested positive for WNV, resulting in 37 hospitalizations and one death. 

WNV circulates between birds and multiple species of mosquitoes. The virus multiplies in the tissues of infected birds and circulates in their blood. Mosquitoes can pick up the virus when taking blood meals from infected birds. The infected mosquitoes can then, in turn, transmit the virus when they fly to another bird or animal and feed again. 

GBPH sets mosquito traps monthly, from May to September, in each Grey-Bruce municipality as part of its West Nile surveillance program. The traps are sent to a laboratory for species identification and viral testing.

So far this year, no positive mosquito pools have been identified in Grey-Bruce.

Other ways to prevent mosquito bites and prevent WNV, include:

• Wearing light-coloured long pants and long sleeves, socks, and a hat when outdoors;
• Reducing mosquito habitats near the home by eliminating standing water in flowerpots, eavestroughs, etc.;
• Taking extra protection measures between dusk and dawn when mosquitoes are most active; and
• Ensuring door and window screens fit securely and are free of holes.

Most people infected with WNV do not experience any symptoms. Others see symptoms two to 15 days after being bitten by an infected mosquito. Symptoms are usually mild and can include fever and headache; however, serious symptoms may also occur.

Some people are at greater risk of experiencing serious health effects from West Nile virus, including individuals over age 50 and people with chronic diseases, such as cancer, diabetes, alcoholism, and heart disease, or who require medical treatment that may weaken their immune system, such as chemotherapy.

Anyone with concerns about a dead bird can contact the Canadian Wildlife Health Co-operative at 1-866-673-4781.

Public Health Ontario has developed an Ontario Vector-Borne Disease Tool, which contains data related to West Nile Virus, along with information on mosquito surveillance.