West Nile virus still a risk, Manitoba entomologist warns

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This article was published 17/8/2017 (610 days ago), so information in it may no longer be current.

Dry weather has helped to keep nuisance mosquitoes at bay in Brandon this summer, but a Manitoba entomologist warns the risk of contracting West Nile virus remains.

"No water does equal no mosquitoes, but the concern is the mosquito that carries West Nile virus, called Culex tarsalis — that mosquito loves these kinds of conditions," said Taz Stuart, entomologist for Poulin’s Pest Control.

Manitoba Health tracks Culex tarsalis trap counts by health region, and Prairie Mountain Health is leading the province.

The latest data, collected during the week of July 30 to Aug. 5, shows PMH had a trap count of 99 Culex tarsalis mosquitoes.

Winnipeg RHA had a count of 58 during the same time period, followed by 47 in the Interlake-Eastern region. The Southern region showed a count of 35.

Out of the Culex tarsalis mosquitoes found in the Prairie Mountain region this summer, 12 have tested positive for West Nile. The Westman communities that have seen a positive mosquito sample include Boissevain, Brandon, Dauphin, Minnedosa, Sioux Valley Dakota Nation and Virden.

In Winnipeg, 10 mosquito samples have tested positive for West Nile, five in Interlake-Eastern and just three in the Southern region.

As of Aug. 11, there have been no human cases of West Nile reported in the province.

"You still need to do personal protection measures," Stuart said. "Don’t assume you’re not dealing with any mosquitoes. That type of mosquito is a very sneaky mosquito. It bites very, very lightly."

Ways to protect yourself include applying insect repellent, wearing light-coloured/loose-fitting clothing with long sleeves and pant legs, and reduce time spent outdoors between dusk and dawn. Make sure doors and window screens fit tightly and are free of holes.

"People need to realize they can bite your ankles, your wrists and they’re active of course at dusk and dawn when everyone wants to be out on their deck having fun," Stuart said.

West Nile can cause severe illness including encephalitis (swelling of the brain) and can sometimes result in long-term complications and death, according to Manitoba Health.

While some people show no symptoms and do not become ill, others may show mild symptoms like headaches, fever, fatigue and body aches. Severe symptoms include severe headache, high fever, mental confusion and muscle weakness.

In Brandon, nuisance mosquito trap counts have remained low for most of the season, only rising to the medium range in July.

As a result, fogging has not been necessary. This week’s average trap count was 35 mosquitoes.

The city would only fog if the numbers remain in the high category for two consecutive trap counts, or the average of any daily mosquito trap count is more than 1,000 or if any individual trap count is more than 2,000.

The city’s 2017 budget included $106,000 for mosquito control initiatives, offset by a $45,000 provincial grant, for a net total of $61,000, according to city treasurer Dean Hammond.

The majority of the budget goes to the mosquito abatement program, which aims to reduce the spread of adult mosquitoes by larviciding standing water.

The budget had earmarked $30,000 for mosquito fogging. Since this will not be used this year, Hammond said it will go into the city’s year-end surplus.

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