The Public Health Agency of Canada says this year’s first human case of West Nile virus acquired within the country has been confirmed in Toronto.
The confirmation comes after Toronto Public Health said its first laboratory-confirmed case of the virus in 2025 is an adult resident of the city with no travel history.
The virus is transmitted to humans through infected mosquitoes.
PHAC’s West Nile surveillance report says that as of July 12, two other Canadian residents were infected this year while travelling outside of the country.
Its surveillance map shows West Nile detections in two mosquito pools in Ontario and one in Manitoba as of that date.
Toronto Public Health says symptoms usually begin between two to 14 days after a mosquito bite and can include fever, headache, nausea, vomiting, body aches, skin rash, swollen lymph glands or a stiff neck.
It says older adults and people with compromised immune systems are at higher risk of severe illness.
People can prevent infection by avoiding mosquito bites – wear light-coloured long sleeves and long pants, use Health Canada-approved insect repellent, put tight-fitting screens on all windows and get rid of standing water in buckets, planters, pool covers and other containers to eliminate mosquito breeding grounds.