July 26, 2007
West Nile Virus Update #6
The Office of the Chief Medical Officer of Health advises that since last week, 11 additional positive human test results for West Nile virus have been reported in Manitoba.
To date, a total of 25 positive test results for West Nile virus have been reported in Manitoba. Twenty-three test results were identified through clinical testing. Two test results were identified through Canadian Blood Services routine screening and the donated blood units were discarded according to plan.
Additional information on these cases including age, gender, regional health authority of residence and likeliest area of exposure will be provided on the website when it becomes available at https://www.gov.mb.ca/health/wnv.
As of today, a new order under Manitoba’s Environment Act is being issued to control adult mosquitoes in East St. Paul. Adult mosquito control based on an order previously issued continues this week in Morden.
Surveillance information indicates that West Nile virus is present in mosquitoes throughout southern Manitoba. Historically, mid-summer has been the time when most humans with identified cases were exposed to infected mosquitoes. The number of cases of the more severe type of West Nile virus (neurologic illness) in previous years has ranged from one to 35 cases per summer.
The chief medical officer of health encourages Manitobans to 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 are advised to reduce mosquito numbers near their homes and in their communities by reducing standing water. To reduce the development of Culex tarsalis mosquitoes:
· clean eavestroughs;
· at least once a 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.
The need for adult mosquito control under orders issued previously in Altona, Beausejour, Boissevain, Brandon, Carman, Deloraine, Headingley, Killarney, Niverville, Oakbank, Stonewall, West St. Paul, Winkler and Winnipeg is under continuous evaluation.
Mosquito samples from nine other communities across southern Manitoba from the week of July 15 were identified as positive for West Nile virus. These communities are Minnedosa, Portage la Prairie, Roblin, Selkirk, Sioux Valley First Nation, Souris, Steinbach, Ste. Anne (town) and Virden. Adult mosquito control has not been recommended in these communities at this time.
To date in 2007, West Nile virus infected mosquitoes have been found in the communities of Altona, Beausejour, Boissevain, Brandon, Carberry, Carman, Dauphin, Deloraine, East St. Paul, Headingley, Killarney, Minnedosa, Morden, Morris, Niverville, Oakbank, Portage la Prairie, Roblin, Russell, Sandy Bay, Sioux Valley, Souris, St. Andrews, Ste. Anne (town), Selkirk, Steinbach, Stonewall, Stony Mountain, Virden, West St. Paul, Winkler, Winnipeg and Winnipeg Beach.
The province continues to monitor adult Culex tarsalis mosquito numbers in these communities and others across southern Manitoba.
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 further reduce their exposure to malathion can take additional 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,
· rinsing any household items or toys left outside before using them, and
· washing fruits and vegetables.
Information on adult mosquito control schedules for West Nile virus and weekly average trap counts of Culex tarsalis by regional health authority is available on the province’s West Nile virus website at https://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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