July 19, 2013
West Nile Virus Update #1
Manitoba Health reports that its mosquito surveillance program has identified this season’s first Culex tarsalis mosquito sample infected with West Nile virus. At this time, no human cases of West Nile virus have been identified in Manitoba in the 2013 season.
The infected mosquitoes were collected during the week of July 7 from an adult mosquito trap in Morris. Based on the most recent information, the numbers of infected mosquitoes are predicted to be low for this area. The current estimated risk does not warrant an order for adult mosquito control.
Although the numbers of Culex tarsalis mosquitoes trapped during the week of July 7 were relatively low, they are increasing in some localities in southern Manitoba. Preliminary trap information for the week of July 14 indicates the numbers of Culex tarsalis mosquitoes have increased from the previous week, particularly in southcentral Manitoba. Most of the mosquitoes in the traps continue to be nuisance mosquitoes, which do not transmit West Nile virus. Culex tarsalis mosquito numbers are highest in southcentral Manitoba, but the potential for human exposure to infected mosquitoes is present throughout southern Manitoba.
The risk of exposure to West Nile virus is expected to increase in the coming weeks, particularly with the current hot, humid weather, which is ideal for Culex tarsalis development and activity.
Manitobans can reduce the risk of mosquito bites and exposure to West Nile virus 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 the number of mosquitoes around their homes by eliminating 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.
The province offers a cost-shared larviciding program for municipalities and communities to take steps to help control Culex tarsalis mosquitoes. To date this year, 56 communities are participating in the program.
Information on the risk of West Nile virus will continue to be provided to the public throughout the summer in a media campaign and at various fairs and festivals. Manitobans can also check the West Nile virus website regularly for up-to-date data and information.
More information about West Nile virus, including weekly average trap counts of Culex tarsalis mosquitoes, fact sheets, posters and information for municipalities and health care providers, is available at www.gov.mb.ca/health/wnv/.
Manitobans can also contact Health Links–Info Santé at 204-788-8200 or at 1-888-315-9257 (toll-free) for more information.
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