Manitoba Health and Healthy Living reports that Manitoba’s mosquito surveillance program has identified the first Culex tarsalis mosquito samples infected with West Nile virus in 2009.
The infected mosquitoes were collected during the week of Aug. 16 from adult mosquito traps in Boissevain in the area of the Assiniboine Regional Health Authority and West St. Paul in the Winnipeg Regional Health Authority’s area. The numbers of infected mosquitoes are relatively low in these communities and no adult mosquito control has been recommended at this time.
Mosquito samples that are positive for West Nile virus may be identified in additional communities in the next few weeks. A risk of exposure to West Nile virus-infected mosquitoes in southern Manitoba is present at this time but, as the weather gets cooler, this risk will decline. In previous years, the peak risk period for human exposure has been the last two weeks of July to the first two to three weeks of August.
Preliminary analysis of adult mosquitoes trapped for the week of Aug. 23 shows the numbers of Culex tarsalis mosquitoes found in surveillance traps have decreased in most communities in southern Manitoba. As daytime and evening temperatures become cooler, Culex tarsalis mosquitoes may become more active during the day and early evening, with reduced activity overnight during cool temperatures.
To date, no human cases of West Nile virus have been identified in Manitoba in the 2009 season.
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 homes 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.
Weekly average trap counts of Culex tarsalis by regional health authority are available on the province’s West Nile virus website at www.gov.mb.ca/health/wnv.
Information on the risk of West Nile virus will continue to be provided to the public throughout the summer. Manitobans can also check the West Nile virus website regularly for up-to-date data and information.
For more information about West Nile virus, contact Health Links-Info Santé at 788-8200 or 1 888 315-9257 (toll-free) or visit the Manitoba Health website at www.gov.mb.ca/health/wnv.
