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.

September 15, 2023

Adult mosquito surveillance conducted during the week of September 3 – September 9, 2023 detected a significant decrease again in the overall numbers of Culex tarsalis mosquitoes compared to the previous week. Culex tarsalis activity was detected in 10 out of 21 trapping communities spread across southern Manitoba. There were no additional WNV positive mosquito pools identified during week 36 in southern Manitoba. To date there have been two confirmed human cases of WNV, 48 WNV positive mosquito pools and 56 WNV positive birds reported to Manitoba Health.

Adult mosquito surveillance has now concluded for the 2023 season.

With the shortening days and cooler nights, Culex tarsalis activity will be limited. The risk of WNV exposure is minimal, however it is not zero. Individuals are still encouraged to adopt personal protection measures (see below) to minimize their risk of WNV exposure when you are outside enjoying the last few weeks of warm temperatures. . These measures should be adopted earlier in the evening as Culex tarsalis will become active earlier with the shortening days.

Manitobans are encouraged to 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 an 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.