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Nile Virus
A summary of information compiled by Ducks Unlimited Canada. Updated June 2010
(PDF, 711kb) - A
Review of Common Mosquito Larvicides
(PDF, 176kb)
Pages in this Article
- Summary
- The Virus Cycle
- Effects on Humans
- Prevention & Mosquito Control
Prevention and Mosquito Control
Preventing mosquito bites is the most important and effective way to prevent contraction of West Nile virus. Culex mosquitoes are most active at dawn and dusk, so it is wise to limit your outdoor activity during these periods. If you must be outside then, use mosquito repellent on exposed skin. Wearing long-sleeved shirts, long pants and light-coloured, loose fitting clothing with a tight weave will also reduce the possibility of being bitten. Screens on windows and doors should be checked and repaired to prevent mosquitoes from getting into the home.
Culex mosquitoes often breed in close association with humans. They particularly like small, container-type wet habitats that are often found around the home and yard. Clogged rain gutters, used tires, untended bird baths and rain barrels, and virtually any other rain-filled container can provide habitat for Culex larvae. It is important to regularly check (at least weekly) and empty containers to ensure that mosquitoes are not being produced in your own yard.
In and around major urban centres, comprehensive mosquito control programs can be effective in reducing their numbers. Such programs rely on insecticides to kill larvae and adults. Larval control is best done through new biological control agents such as the larvicide Bti (Bacillus thuringiensis israelensis) – a naturally occurring soil bacterium that is very effective at controlling larval mosquitoes and has little impact on the rest of the aquatic community. Adult mosquito control may be required when larviciding is unable to control mosquito numbers and public health officials recognize an imminent danger to human health.
In rural settings, it is virtually impossible to eliminate all potential Culex breeding sites that are present on the landscape. Adult mosquitoes are quite capable of moving great distances. Therefore, applications of insecticides to individual aquatic habitats will not effectively reduce mosquito populations with respect to controlling the spread of West Nile. Personal protection is the only effective means of preventing exposure to West Nile virus in rural areas. West Nile virus is new to North America and there are still many unknowns. In 2002, the virus spread further and was more deadly than anyone thought possible the previous year.
Its impact as it spreads across the rest of the continent and into Central and South America is unknown. We do not know the full impact on wildlife populations, particularly among birds. Mosquito control efforts are being increased, but we must ensure that the methods used are properly targeted.
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