August 11, 2005
Initial test results indicate four additional human cases of West Nile virus in Manitoba, bringing the total number of Manitobans who have tested positive for West Nile virus this year to seven.
One of these cases is an Interlake Regional Health Authority resident in her 30s. Based on information provided to health officials, it is likely the individual was exposed in mid-July in the town of Arborg. The individual, who was not hospitalized, will be reported to Health Canada as a probable case of West Nile non-neurological syndrome.
Of the seven Manitobans who have tested positive this year, one has been classified as a probable case of West Nile neurological syndrome and two have been classified as probable cases of West Nile non-neurological syndrome. The rest are currently under investigation to determine if they meet the criteria for probable cases of West Nile virus.
As of Aug. 10, 882 people have been tested for WNV in Manitoba.
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 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.
At this time, 24 communities in Manitoba have had West Nile virus positive mosquito samples. Mosquito samples have tested positive for West Nile virus in the communities of Altona, Carman, Morden, Selkirk, Ste. Anne, East St. Paul, Carberry, Killarney, Souris, Roblin, Oakbank, Niverville, Stonewall, Morris, Boissevain, Deloraine, Brandon, Virden, Winkler, Steinbach, Winnipeg and West St. Paul. During the week of July 31 to Aug. 6, positive mosquito samples were identified in Russell and Stony Mountain for the first time this season.
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.
During the week of July 31 to Aug. 6, average Culex tarsalis counts increased in the Brandon, Central and South Eastman regional health authorities. Weekly average counts in the Winnipeg regional health authority decreased from the previous week. Weekly averages in other regional health authorities remained relatively unchanged or were lower than the previous week.
Adult mosquito control under a ministerial order 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 remains on hold in the town of Carman and the R.M. of East St. Paul based on data showing 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, Burntwood and Churchill regional health authorities will continue to be 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.
- 30 -