August 04, 2005

Initial test results indicate three human cases of West Nile virus in Manitoba.

Further testing and investigation is underway to confirm these are cases of West Nile virus, when and where exposure may have taken place and the severity of illness.

In previous years, the last week of July and the month of August have been the peak period for the risk of human exposure to West Nile virus in Manitoba. Surveillance data indicate that the virus is present throughout southern Manitoba at this time.

Now and throughout the month of August 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,

• reducing standing water around homes, and

• wearing light-coloured, loose-fitting clothing.

These initial test results are the first indication of human infection with West Nile virus in Manitoba in 2005. As of Aug. 3, 663 people have been tested for WNV in Manitoba.

At this time, 22 communities have had positive West Nile virus mosquito samples this year. Mosquito samples collected during the week of July 24 have tested positive for West Nile virus in the communities of:

• Carberry,

• Killarney,

• Souris,

• Roblin,

• Oakbank,

• Niverville,

• Stonewall, and

• Morris.  

As well, during the week of July 24, additional positive samples were found in several communities with previous positive mosquito samples. These communities are Boissevain, Deloraine, Brandon, Virden, Winkler, Steinbach, Winnipeg and West St. Paul.

Analysis of the data from the above communities will continue to determine the potential risk of human exposure to West Nile virus. Testing of mosquitoes for WNV is ongoing at Cadham Provincial Laboratory. 

Last week, average Culex tarsalis counts increased in the Assiniboine, Central and Winnipeg regional health authorities. Weekly averages in other regional health authorities were generally lower than the previous week.

Adult mosquito control under ministerial orders is continuing in the city of Winnipeg, the R.M. of West St. Paul and the city of Winkler. Adult mosquito control under a ministerial order has been put on hold in the town of Carman and the R.M. of East St. Paul based on data showing a lower number of mosquitoes and a reduced human health risk.

The provincial WNV bird surveillance program has established the presence of West Nile virus throughout southern Manitoba. Therefore, no further birds will be picked up in southern Manitoba. Birds from the NOR-MAN Regional Health Authority, the Burntwood Regional Health Authority and the Churchill Regional Health Authority will continue to tested for WNV to establish the presence of WNV in those areas.

Public information about West Nile virus and mosquito control in areas under a health order is available by calling Health Links-Info Santé at 788-8200 in Winnipeg or toll-free at
1-888-315-9257. Information is also available on the Manitoba Health website at http://www.gov.mb.ca/health/wnv.

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