Winnipeg on path to shatter 'unprecedented' mosquito record

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Published June 21, 2019 2:55 p.m. ET
Updated June 21, 2019 3:06 p.m. ET
CTV Winnipeg: Mosquitoes

When Manitobans see the words “mosquito” and “record” in a sentence, it usually draws panic -- but not this time.

With the weather Winnipeg has been experiencing so far this mosquito season, the city is hopeful for another smooth summer. Even with rain in the forecast Saturday and Sunday, concern is low, much like the daily average trap count, which is currently at just two mosquitoes.

Superintendent of Insect Control Ken Nawolsky said the lack of mosquitoes last summer, which broke records, was unusual.

“That was like a one in 50-year event, and we might be heading that way, too,” said Nawolsky. “We’ve still got some weeks left, but so far so good.”

In 2017, the city made the switch from using the insecticide malathion to Delta Guard, which Health Canada approved for adult mosquito control -- but insect control hasn’t had to use the new product yet.

“If we do happen to not do any fogging or have low mosquito numbers, that’s pretty unprecedented to have it three years in a row. We’re trying to look at shattering another record.”

Nawolsky said the product doesn’t expire, so there’s no concern with it sitting while Winnipeggers enjoy the lack of mosquitoes. Fogging doesn’t occur until the trap count average is approximately 100 mosquitoes in one or more areas.

With below average precipitation so far this season, Nawolsky said it would take a lot for the mosquito population to boom.

“We would be looking at anything more than about 50 millimetres, and that would have to be a severe downpour or prolonged rain event,” said Nawolsky. “Then we’d definitely have a challenge ahead of us.”

Insect control begins monitoring for mosquitoes in the last week of April until mid-September, and based on surveillance data Nawolsky said levels should remain low for the upcoming weeks.

Watching for West Nile

Manitobans still need to be on the lookout for West Nile virus (WNV) despite the smaller mosquito population.

Manitoba Health said it typically begins monitoring for the virus in a handful of communities in late May, and surveillance is fully operational by early June. It said WNV is widespread in Manitoba, though the number of human cases varies from season to season based on a number of factors, like environmental conditions, rainfall, and virus activity.

Last year there were 34 human cases of WNV in Manitoba. In 2017 there were five, and in 2016 there were 23.

“The cool and dry condition experienced in 2017 resulted in lower activity,” said a provincial spokesperson in an email to CTV News. “In 2018, activity was increased in response to the above normal temperatures, dry conditions and abundant West Nile virus circulation.”

The province said there were 168 positive mosquito pools in 2018, which was the most detected in a year since 2007.

“Occasionally conditions exist where there are low mosquito numbers and low virus activity which leads to lower numbers of human cases.”

Historically, the province said Manitobans are most at risk from June to September.

“It only takes a single bite to become ill with West Nile,” said the spokesperson. “As Manitobans enjoy their summer they need to take care to prevent mosquito bites even when it may seem like there are few mosquitoes around. There is no cure, treatment or vaccine for West Nile virus.”

Manitobans are reminded to dump any standing water on their properties to prevent mosquitoes from growing.

To date mosquito activity is low in the province, and no mosquitoes have tested positive for the virus.

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