West Nile virus confirmed in southwestern Ontario mosquito trap

A mosquito trap in Aylmer, Ont., has tested positive for the West Nile virus.

The Southwestern Public Health Unit (SWPH) confirmed the positive test on Tuesday, saying this is the first mosquito trap to produce a positive test in the region in 2023.

“We have mosquito traps set up across Oxford County, Elgin County, and the City of St. Thomas to monitor and test for the presence of West Nile virus in our region,” said Dr. Ninh Tran, SWPH medical officer of health.

According to the health unit, around 80 per cent of people who become infected with the mosquito-born virus do not get sick. Those who do usually experience mild flu-like symptoms, while fewer than one per cent get seriously ill.

“The main concern is neurological disease and complications, including meningitis and flaccid paralysis,” Tran said.

Earlier this year, SWPH confirmed that a bird in the region had tested positive for West Nile virus a week before regular seasonal surveillance began.

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However, Tran told Global News that the last case of West Nile recorded in a person within the region was back in 2018.

“In previous years, mosquito traps tend to come back positive roughly around this time, so it is something that’s generally expected in the season,” he said, adding that they’re currently in the process of taking further action to reduce the chances of a spread.

“Commonly, what we do is use larvicide. We use this insecticide in areas where we expect mosquitos to be and try to kill off as many larvae as we can,” he said.

Tran also advises the public to wear DEET-based repellents, long-sleeved clothing, and limit time around still water where mosquitoes are known to breed.

The health unit also recommends the following:

• repair holes in screens, windows and doors
• empty standing water regularly around your property, such as from pool covers, toys, flowerpots, garbage cans, and any other outdoor object that can collect water
• change water in bird baths every other day
• keep pool pumps circulating
• install screens to cover the opening of rain barrels

SWPH is also advising the public to contact their primary care provider if they experience flu-like symptoms after being bitten by a mosquito.

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