Weekly West Nile Virus Update

 

The WNV Story Map may not always be updated at the same time as the WNV Surveillance Statistics website and the Weekly Update. Please check back later if the Story Map does not align with the Weekly Surveillance Statistics and Weekly Update.

August 28, 2026

One additional round of fogging with DeltaGard 20EW was completed in the RM of West St. Paul on August 22 to reduce the risk of exposure to West Nile virus (WNV) due to high numbers of infected mosquitoes.

Two probable human WNV cases were reported this week, one each in the Interlake-Eastern and Southern Health/Santé Sud regions. To date, six human WNV cases have been reported (1 confirmed, 5 probable).

Adult mosquito surveillance during the week of August 16 to 22, 2026 (week 33) detected C. tarsalis mosquitoes in all 21 trapping communities in Manitoba. The average number of C. tarsalis per trap decreased in all health regions except Prairie Mountain health region compared to the previous week. The provincial average remained slightly higher than the historical average for week 33. More details are available at: https://www.gov.mb.ca/health/wnv/stats.html.

60 West Nile virus (WNV)-positive C. tarsalis mosquito pools were detected in Week 33 including in Prairie Mountain Health (Brandon and Boissevain), Interlake-Eastern Health (Stonewall and Gimli/Winnipeg Beach), Southern Health/Santé Sud (Altona, Carman, Killarney, Portage la Prairie, and Winkler) and Winnipeg Health regions (Winnipeg and West St. Paul). 21 WNV-positive birds and 0 WNV-positive horses were reported this week. To date, 393 WNV-positive C. tarsalis pools, 43 WNV-positive birds, and one WNV-positive horse have been identified.

As of August 27, the risk of human exposure to WNV in Manitoba is high. July and August are historically the months with the highest risk of WNV. Culex tarsalis activity is decreasing. However, with the continued detection of WNV infection in mosquitoes, Manitobans are still encouraged to take precautions to minimize their risk of mosquito bites while enjoying outdoor activities over the next few weeks. This includes:

  • reducing the amount of time spent outdoors during peak mosquito hours between dusk and dawn;
  • using appropriate mosquito repellent;
  • wearing light-coloured, loose-fitting clothing with long sleeves and pant legs, and
  • maintaining door and window screens so they fit tightly and are free of holes.

Manitobans can also reduce the number of mosquitoes around their home by eliminating standing water. To reduce standing water:

  • clean eaves troughs and regularly empty bird baths and other items that might collect water,
  • ensure rain barrels are covered with mosquito screening or are tightly sealed around the downspout,
  • clear yards of old tires or other items that collect water, and
  • improve landscaping to prevent standing water around the home.