August 10, 2006
Initial test results indicate four additional human cases of West Nile virus have been identified in Manitoba, bringing the total number of Manitobans who have tested positive for West Nile virus this year to nine.
Of the nine Manitobans who have tested positive this year, three have been classified as cases of West Nile neurological syndrome and two have been classified as cases of West Nile non-neurological syndrome. The rest are currently under investigation to determine if they meet the criteria for cases of West Nile virus.
Additional information on these cases, such as age, gender, regional health authority of residence and likeliest area of exposure, will be provided on the website when it becomes available at http://www.gov.mb.ca/health/wnv.
In previous years, the last week of July and the first three weeks of August have been the peak period for the risk of human exposure to West Nile virus in Manitoba. Even though mosquito activity may appear to be low, this is the most important time to take personal protective precautions against mosquitoes in both urban and rural areas.
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
making sure doors and window screens fit tightly and are free of holes.
Adult mosquito trap information from the week of July 30 indicates the numbers of Culex tarsalis mosquitoes in southern Manitoba generally remained similar compared to the numbers from the week of July 23.
Preliminary trap information from the week of Aug. 6 indicates the Culex tarsalis numbers in many southern Manitoba communities generally continued to be similar compared to the numbers from the week of July 30, with some communities showing a reduction in weekly average counts.
During hot weather, mosquitoes are less likely to be active during the day and more likely to be active at dusk. This is particularly true for Culex tarsalis, which are often less noticeable than nuisance mosquitoes. Heat affects the development of Culex tarsalis mosquitoes and their activity increases when the average daily temperature is above 16 C.
This year, positive mosquito samples have been found in 18 Manitoba communities: Steinbach, Carman, Selkirk, Boissevain, Carberry, Portage la Prairie, Gimli, Niverville, St. Andrews, Beausejour, Headingley, West St. Paul, Winnipeg, Brandon, Deloraine, East St. Paul, Stony Mountain and, this week, Oakbank.
At this time, the only community where an order for adult mosquito control has been issued is for a targeted area of the Rural Municipality of West St. Paul. Two nights of spraying have been completed. Further spraying will depend on the results of ongoing mosquito surveillance.
Information on adult mosquito control for West Nile virus, including spraying schedules, is available on the Manitoba Health website at http://www.gov.mb.ca/health/wnv.
Manitobans can reduce the number of Culex tarsalis mosquitoes around their homes by reducing standing water. This includes:
regularly cleaning and emptying eavestroughs, bird baths and other items that might collect water;
ensuring rain barrels are covered with mosquito screening or are tightly sealed around the downspout; and
making sure yards are clear of old tires or other debris that collect water.
Weekly average trap counts of Culex tarsalis by regional health authority are available on the province’s West Nile virus website at http://www.gov.mb.ca/health/wnv.
For more information, visit the website or call Health Links at 1‑888‑315‑9257 or 788-8200 in Winnipeg.
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