June 28, 2007
WEST NILE VIRUS BULLETIN #3
– – –Adult Mosquito Control for WNV Ordered for Altona, Stonewall, Winkler, West St. Paul; West Nile Virus Risk Increases in Manitoba
Orders under Manitoba’s Environment Act will be issued to control adult mosquitoes in Altona, Stonewall, Winkler and West St. Paul. At this time, a significant number of Culex tarsalis mosquitoes have become infected with West Nile virus in these communities.
In addition, the Office of the Chief Medical Officer of Health reports mosquito samples from five other communities across southern Manitoba from the week of June 17 were identified as positive for West Nile virus. These communities are Boissevain, Virden, Sioux Valley, Stony Mountain and Steinbach. Surveillance indicates these communities have lower numbers of infected mosquitoes and adult mosquito control has not been recommended in these communities at this time.
Culex tarsalis mosquitoes are the mosquitoes in Manitoba most likely to carry the West Nile virus. These mosquitoes have been found in increasing numbers over the past several weeks in a number of communities in southern Manitoba. The province continues to monitor adult Culex tarsalis mosquito numbers in these communities and across southern Manitoba.
To date, one human case of West Nile virus has been identified in Manitoba in a blood donor. In previous years, the last weeks of July and the first few weeks of August have been the peak period for the risk of human exposure to West Nile virus in Manitoba. The risk of being exposed to West Nile virus has increased in some parts of southern Manitoba and is expected to increase in the coming weeks. The risk of severe illness from West Nile virus in previous years has ranged from one to 35 severe cases in a summer.
Planning is underway for adult mosquito control to reduce the risk of West Nile virus in Altona, Stonewall, Winkler and West St. Paul. Mosquito fogging will take place in the evening and at night, weather conditions permitting.
Information on adult mosquito control schedules for West Nile virus and a description of the areas to be sprayed will be available on the Manitoba Health website at http://www.gov.mb.ca/health/wnv as it becomes available.
Health Canada has concluded the use of malathion for adult mosquito control in residential areas using ultra-low-volume application will not pose a health concern. However, people who wish to reduce their exposure to malathion can take precautions including:
· closing all doors and windows,
· avoiding trucks while spraying is underway,
· turning off fans and air conditioners or setting them at exhaust,
· removing clothes and children’s toys from outdoor areas,
· washing any household items or toys left outside before using them, and
· washing fruits and vegetables.
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 near their homes and in their communities by reducing standing water. To reduce the development of Culex tarsalis mosquitoes:
· clean eavestroughs;
· at least once per week, empty bird baths and other items that might collect water;
· cover rain barrels with mosquito screening or maintain tight seals around downspouts; and
· dispose of old tires or other debris that collect water.
Weekly average trap counts of Culex tarsalis by regional health authority will be available on the province’s West Nile virus website at http://www.gov.mb.ca/health/wnv. Updated information on the risk of West Nile virus will be provided to the public throughout the summer. Manitobans can check the West Nile virus website regularly for up-to-date data and information.
More information about West Nile virus is also available from Health Links–Info Santé at 788-8200 or 1‑888‑315-9257.
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