Canada’s first West Nile case in 2025; what to watch for and how to stay safe

The Public Health Agency of Canada (PHAC) has confirmed the country’s first human case of West Nile virus acquired within Canada this year. According to Toronto Public Health, as reported by Global News, the case involves an adult Toronto resident with no recent travel history.

West Nile virus is spread to humans through the bite of an infected mosquito. PHAC's latest surveillance report, dated July 12, also recorded two other Canadian residents infected while traveling abroad earlier this year.

The agency’s mosquito monitoring map has detected West Nile virus in two mosquito pools in Ontario and one in Manitoba.


Toronto Public Health warns that symptoms typically appear within 2 to 14 days of a mosquito bite.

Common signs include fever, headache, nausea, vomiting, body aches, rash, swollen lymph nodes, or stiff neck. Severe illness is more likely in older adults and those with weakened immune systems.

To reduce the risk of infection, residents are advised to wear light-colored long sleeves and pants, use insect repellent approved by Health Canada, install tight-fitting screens on windows, and eliminate standing water where mosquitoes can breed.

FAQs

What is West Nile virus and how is it transmitted?

West Nile virus is a mosquito-borne virus that spreads to humans through the bite of an infected mosquito. It is not spread through person-to-person contact.

How can I prevent getting infected with the West Nile virus?

You can reduce your risk by wearing light-colored, long-sleeved shirts and pants, using insect repellent approved by Health Canada, installing tight-fitting screens on windows and doors, and removing standing water from items like buckets, planters, and pool covers to eliminate mosquito breeding sites.

Is there a cure or specific treatment for West Nile virus?

There is no specific antiviral treatment or cure for West Nile virus. Most people recover fully on their own, but severe cases may require hospitalization for supportive care.

Has West Nile virus been detected elsewhere in Canada this year?

As of July 12, mosquito pools in Ontario and Manitoba have tested positive for the virus. Two Canadians were also infected while traveling outside the country.

When is mosquito activity typically the highest?

Mosquitoes are most active from dusk to dawn during the warmer months, especially July through September in Canada.