Recent hot, humid conditions have created ideal conditions for the development of Culex tarsalis mosquitoes, biting activity and the transmission of West Nile virus. Manitoba Health is reporting a high risk of exposure to West Nile virus (WNV) throughout southern Manitoba and Manitobans are urged to take special care to reduce the risk of mosquito bites and WNV, even when there do not appear to be many mosquitoes.
So far this season, 20 positive WNV mosquito samples have been identified. No positive mosquito samples were identified in 2011. No human cases of West Nile virus have been reported to this point.
During the week of July 15, the Manitoba Health mosquito surveillance program identified Culex tarsalis mosquito samples infected with WNV in 11 communities including Altona, Beausejour, Brandon, Carberry, Deloraine, Selkirk, the Sioux Valley First Nation, Ste. Anne, Stonewall, West St. Paul and Winnipeg. The number of Culex tarsalis mosquitoes has increased across southern Manitoba, most significantly in southwest and central Manitoba.
To reduce the risk of mosquito bites and West Nile virus, Manitobans are encouraged to:
reduce the amount of time spent outdoors during peak mosquito hours between dusk and dawn;
use appropriate mosquito repellent;
wear light-coloured, loose-fitting clothing; and
maintain 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.
Although there is an elevated risk of WNV and the above precautions are encouraged, an adult mosquito control program is not deemed necessary at this time. However, Manitoba Health will continue to monitor the situation.
Manitobans can check the West Nile virus website regularly for up-to-date data and information including weekly average trap counts of Culex tarsalis mosquitoes by regional health authority.
For more information about West Nile virus, contact Health Links–Info Santé at 204-788-8200 or
toll-free at 1-888-315-9257 or visit the province’s West Nile virus website at www.gov.mb.ca/health/wnv.