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B.C. Health officials set up mosquito traps in the Sea to Sky region for study

VANCOUVER — Mosquito traps have been set up across the Sea-to-Sky region in British Columbia as health officials launch a pilot project to understand the area's mosquitoes and the illnesses they spread.
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Mosquitoes cling to the inside of a jar loaded with repellent during a test as part of a tour of the Centers for Disease Control laboratory, Thursday, April 4, 2024, in Fort Collins, Colo. THE CANADIAN PRESS/AP, David Zalubowski

VANCOUVER — Mosquito traps have been set up across the Sea-to-Sky region in British Columbia as health officials launch a pilot project to understand the area's mosquitoes and the illnesses they spread.

Vancouver Coastal Health said Friday that there were four cases of mosquito-borne illnesses late last year, that resulted in swelling of the brain, and all the patients likely acquired the infections in the area along Howe Sound and north to Whistler and Pemberton.

Dr. Moliehi Khaketla, medical health officer for Vancouver Coastal Health, said in an interview that the viruses aren't new to B.C., but it's unusual to see these "very severe" human cases.

"So, this prompted us to study further, just to see and better characterize what is happening within the Sea to Sky area," said Khaketla

Traps have already been set up in the region, she said.

The health authority said the four patients have recovered from their illness.

The mosquito project will last for three months, and Vancouver Coastal Health said it wants to learn more about the risk to the public. In the meantime, those in the area should take preventive measures against mosquito bites, it said.

Khaketla said the purpose of the study is to help health officers learn more about the mosquito population within that corridor and understand what specific viruses that they are carrying.

"We wanted people to be aware of the mosquito circulation within the Sea to Sky area, as it is summer months, we expect mosquitoes to circulate."

The mosquito-borne illnesses, part of the so-called California Serogroup viruses, usually do not cause symptoms, but when they do occur, they are flu-like, with a fever, headache, fatigue, and occasional nausea or vomiting.

The health authority said in a statement that cases of mosquito-borne illnesses usually occur between May to October when there is increased mosquito activity, but this period may be extended due to "increasingly warmer temperatures" from climate change.

The authority said those who have been in the Sea-to-Sky region and develop symptoms of severe headaches with fever or seizures are advised to seek care immediately.

Measures to protect against bites, include wearing protective clothing, and avoiding any stagnant water around backyards that can be pools for mosquito breeding, said Khaketla.

Vancouver Coastal Health, the B.C. Centre for Disease Control, partners from the Lil'wat Nation and Squamish nations and the University of British Columbia will collaborate on this surveillance pilot project.

This report by The Canadian Press was first published July, 18, 2025.

Nono Shen, The Canadian Press