Manitoba Health, Seniors and Long-Term Care has issued a ministerial order under the Environment Act to spray for adult mosquitoes with DeltaGard 20EW in affected communities due to risk of exposure to 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 is currently in the highest-risk period for human exposure, which historically occurs between July 15 and Aug. 15 each year.

Surveillance data from last week showed high numbers of adult Culex tarsalis mosquitoes and evidence of infection with West Nile virus. Mosquito counts exceeded the threshold for the province to begin adult mosquito control in the following communities:

  • Carman, plus an approximate three-kilometre (km) radius extension into the Rural Municipality (RM) of Dufferin.
  • Stonewall, plus an approximate three-km radius extension into the RM of Rockwood.
  • RM of West St. Paul.
  • Winkler, plus an approximate three-km radius extension into the RM of Stanley including Reinfeld, Chortitz and Schanzenfeld.
  • Winnipeg neighbourhoods within an approximate three-km radius of: the intersection of Kenaston Boulevard and North Town Road; the intersection of King Edward Street and Old Commonwealth Path; and the intersection of the north Perimeter Highway and Provincial Trunk Highway 8.

Spraying is scheduled to begin as early as Friday, July 31, weather permitting.

Confirmed dates will be communicated through municipalities and posted on the 2026 schedule of adult mosquito control across southern Manitoba under ministerial order at gov.mb.ca.

Approved by Health Canada for use in 2017, DeltaGard 20EW is classified as a reduced-risk pesticide. When applied using ultra-low volume methods and according to label directions, DeltaGard 20EW is unlikely to affect human health.

To date, there have been no human cases of West Nile virus confirmed in Manitoba in 2026. A single bite from an infected mosquito can transmit West Nile virus to humans. Infection may cause severe illness resulting in encephalitis (swelling of the brain), long-term complications and death.

For more information on West Nile virus in Manitoba, including surveillance data, prevention tips and symptoms of infection, visit gov.mb.ca.