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.

July 17, 2026

Adult mosquito surveillance conducted during the week of July 5 - July 11, 2026, (week 27) detected Culex tarsalis mosquitoes in 20 of 21 trapping communities in southern Manitoba. Numbers were increased from the previous week and were slightly higher than normal for week 27.

Three West Nile virus (WNV) -positive C. tarsalis mosquito pools were detected in Week 27, one each in Interlake-Eastern, Southern Health/Sante Sud, and Winnipeg Health regions. To date, three WNV-positive C. tarsalis pools, one WNV-positive bird and zero WNV-positive horses have been identified. No human cases have been reported in the province this year.

Hotter temperatures in the past week are supporting Culex tarsalis development. Preliminary data for week 28 (July 12 – July 18) indicate a rapid increase in C. tarsalis numbers. While the risk of WNV exposure last week was low, risk is expected to increase in July and August, which are historically the months with the highest risk of WNV.

A recent media bulletin urged Manitobans to take precautions against WNV and Lyme disease. Manitobans are encouraged to enjoy outdoor activities and reduce the risk of mosquito bites and exposure to WNV by:

  • 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 using these steps 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.