York Region confirmed its first human case of West Nile virus in 2025, after an individual in Vaughan tested positive, the region announced in an Aug. 8 media release.

This occurred after the region reported, via a release on July 17, that a Vaughan mosquito trap tested positive for the virus.

The region has since confirmed a total of four positive cases of West Nile virus and eight positive mosquito traps throughout 2025, including one trap in Markham.

West Nile virus is one of several viruses that are transmitted by mosquitoes. Most infected people remain asymptomatic, but some may develop signs such as fever, muscle weakness, stiff neck, confusion, severe headaches, and sudden sensitivity to light.

The virus can cause life-threatening symptoms – such as brain inflammation – in severe cases. Older adults and those with weaker immune systems are at a greater risk of developing severe symptoms.

Anyone experiencing any of the above symptoms should seek medical attention.

In both releases, York Region recommended that residents clean up outdoor sources of standing water to deter mosquitoes from their homes. The July 17 release recommended that residents check the quality of their window screens as well.

Both releases also recommended wearing light-coloured clothes with full coverage – such as long-sleeved shirts and pants, as well as using Health Canada-approved insect repellent containing DEET or icaridin.

York Region implements an annual West Nile virus control plan to minimize the spread of West Nile virus. This includes exterminating mosquitoes using provincially and federally approved pesticides, educating residents on self-protection measures, and monitoring mosquitoes through mosquito traps.

The region sets up to 40 mosquito traps every week between June and October.

For more information about the West Nile virus, visit york.ca/WestNile.

 

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