Province orders mosquito fogging owing to increased risk of West Nile virus

Parts of Winnipeg and several rural communities will be sprayed for mosquitoes in the coming days as the heat wave across southern Manitoba has created a higher risk of exposure to West Nile virus.

The province has issued a fogging order under the Environment Act in response to a high number of Culex tarsalis mosquitoes — the primary transmitter of West Nile virus — in Manitoba.

Surveillance data from last week showed evidence of the West Nile virus.

“High temperatures across southern Manitoba have shortened the time required for West Nile virus to develop within infected Culex tarsalis mosquitoes and be transmitted to humans,” the province’s first bulletin on West Nile virus this summer, published Thursday afternoon, reads.

“The province is currently in the highest-risk period for human exposure, which historically occurs between July 15 and Aug. 15 each year.”

In trap counts from July 5 to 11, an average of 19.9 Culex tarsalis mosquitoes were found per trap, while from July 12 to 18, the most recent data available, an average of 154.9 Culex tarsalis mosquitoes were collected.

In Winnipeg, the trap counts jumped from 15.3 collected to 156.2 in the same time period.

There have been no confirmed cases of West Nile virus in Manitoba so far this year. There were four confirmed cases of West Nile virus in Manitoba in 2025, and 10 in 2024.

A single bite from an infected mosquito can cause the virus to transmit to a human, and can result in serious illness, including brain swelling and death.

Spraying is set to begin Friday and continue into next week, weather permitting. DeltaGard 20EW will be sprayed within a three-kilometre radius of the following areas in Winnipeg:

• The intersection of Kenaston Boulevard and North Town Road on Saturday and Tuesday.
• The intersection of King Edward Street and Old Commonwealth Path Friday and Monday.
• The intersection of the north Perimeter Highway and Provincial Trunk Highway 8 Friday and Monday.

And the following rural areas:

• Carman, along with an approximate three-kilometre radius into the Rural Municipality of Dufferin Saturday and Tuesday.
• Stonewall, along with an approximate three-kilometre radius extension into the Rural Municipality of Rockwood Friday and Monday.
• The Rural Municipality of West St. Paul Friday and Monday.
• Winkler, along with an approximate three-kilometre radius extension into the Rural Municipality of Stanley including Reinfeld, Chortitz and Schanzenfeld, Saturday and Tuesday

The City of Winnipeg said Thursday it would spray for mosquitoes with DeltaGard 20EW beginning at 9:30 p.m. Friday in the following areas:

• Fairfield Park, Richmond West, Waverley West, Waverley Heights, Bison Run, Bridgwater Centre, Bridgwater Forest, Bridgwater Lakes, Bridgwater Trails, Prairie Pointe, and South Pointe.
• Whyte Ridge.
• Linden Ridge and West Fort Garry Industrial.
• North Inkster Industrial and Tyndall Park.
• Burrows-Keewatin, and Inkster Industrial Park.
• Inkster Gardens, Mandalay West and The Maples.
• Amber Trails and Rosser-Old Kildonan

malak.abas@freepress.mb.ca