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 25, 2025
Adult mosquito surveillance conducted during the week of July 13 to July 19, 2025 (week 29) detected Culex tarsalis mosquitoes in 19 of 21 trapping communities in Manitoba. Numbers were increased from the previous week but were still below average for week 29.
15 West Nile virus (WNV) positive Culex tarsalis mosquito pools and 3 WNV positive birds were detected in Week 29. To date,16 WNV-positive Culex tarsalis pools, three WNV-positive birds and zero WNV-positive horses have been identified. One confirmed WNV human case was reported, related to travel outside of Canada.
Recent rainfall and hotter temperatures are supporting Culex tarsalis development. The risk of WNV exposure increased to moderate and is expected to increase further in July and August, which are historically the months with the highest risk of WNV.
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 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.
