Toronto Public Health reports 1st probable human case of West Nile Virus in 2023

The first probable human case of West Nile Virusof 2023 has been reported in Toronto, the city's public health agency said Friday.

In a news release, Toronto Public Health (TPH) said the likely case is in an adult resident. It has yet to be confirmed by laboratory testing.

"While the risk of being infected with West Nile virus remains low in Toronto, 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," said Dr. Eileen De Villa, the city's medical officer of health, in the release.

"Apply insect repellent, wear light-coloured clothing, long pants, long-sleeved shirts and take extra care between dusk and dawn, which are peak mosquito-biting hours."

The virus is transmitted through the bite of an infected mosquito and symptoms couldinclude:

• Fever.
• Headache.
• Nausea.
• Vomiting.
• Body aches.
• Skin rash.
• Swollen lymph glands.

Any symptoms that might develop generally begin around two to 14 days after being bitten, TPHsaid. Older people, especially those with compromised immune systems, are at higher risk of experiencing more severe illness from the virus.

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There were 14 laboratory-confirmed cases of West Nile in the city in 2022, according to the release.

The city carries out mosquito surveillance using 22 traps from mid-June through mid-September every summer. Each week, mosquitos from those traps, called batches, are sent to a lab for testing. So far this year, 20 batches have tested positive for West Nile, TPH said.

"With the increased hot weather in Toronto lately, there is a higher risk of mosquitos that can transmit the virus once they are infected," the release said.

Multiple GTAregions and cities have recently reported finding mosquitos positive for the virus, including Brampton, Markham and Hamilton.