Manitoba Health

West Nile Virus Update

September 28, 2011

While 2011 has been a relatively low year for Culex tarsalis mosquitoes and risk of exposure to West Nile virus (WNV), the risk will remain present until the first killing frosts.  Personal protective measures, such as using an appropriate repellent, will help to reduce mosquito bites.

At this time, the risk of exposure to West Nile virus-infected mosquitoes is low and declining, but not zero.  Analysis of the adult mosquitoes trapped for the week of September 11 show very low numbers of Culex tarsalis mosquitoes. 

None of the mosquitoes collected to date have tested positive for West Nile virus.  Adult mosquito surveillance is now complete for 2011.

Manitobans can reduce the risk of mosquito bites 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; and
• maintaining door and window screens so they fit tightly and are free of holes.

Manitobans can reduce mosquitoes around their home by reducing standing water.  To prevent the development of Culex tarsalis mosquitoes, homeowners can: 

• clean eavestroughs 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.