First probable human case of West Nile virus reported in Toronto for 2023: officials

The first probable case of West Nile virus found in a human in 2023 has been reported by health officials in Toronto.

In a news release issued Friday, Toronto Public Health (TPH) said while the odds of contracting West Nile remains low, the hot weather can bring a “higher risk” of infected mosquitoes transmitting the virus.

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“Now is a good time to remind residents ahead of the long weekend of the steps they can take to avoid bites from infected mosquitos when enjoying the beautiful summer weather,” Chief Medical Officer of Health Dr. Eileen de Villa said in a statement.

Last month, officials reported that West Nile virus had been detected in a group of mosquitoes collected in Toronto during routine testing.

The infected mosquitoes were trapped in northwest Scarborough and were the first scourge to test positive for the virus in 2023. TPH did not disclose where in the city the infection of the first probable human case of the season occurred.

West Nile virus symptoms usually start to show between two and 14 days after a person is bitten, TPH said. Those symptoms may include fever, headache, nausea, vomiting, body aches, skin rash and swollen lymph glands. Officials said older individuals and those with compromised immune systems are at a higher risk of severe illness if they are bitten.

Since the city reported its first batch of infected mosquitoes on July 18, at least 19 additional pools of insects carrying the virus have been identified.

Last year, TPH said, 14 human cases of West Nile virus were confirmed and as many pools of infected mosquitoes were identified.

If you’re concerned you may have been infected, TPH suggests contacting your health-care provider.

Here are a number of tips to avoid getting infected:

• Apply insect repellent containing N,N-diethyl-meta-toluamide (DEET) or icaridin
• Wear light-coloured clothing, long pants and long-sleeved shirts outdoors
• Make sure screens on windows and doors are fitted
• Remove standing water where mosquitoes can breed
• Take extra care during peak mosquito-biting hours, dusk and dawn

The city’s West Nile virus webpage has additional information and resources on reducing infection here.