August 18, 2005
Initial test results reported since Aug. 11 indicate five additional suspected human cases of West Nile virus (WNV) in Manitoba. This brings the total number of Manitobans that have tested positive for West Nile virus this year to 12.
Following investigations by regional public health officials, three have been classified as probable cases of West Nile neurological syndrome. These individuals have been hospitalized. Three cases have been classified as probable cases of West Nile non-neurological syndrome. These individuals did not require hospitalization. No deaths have been reported.
The other six suspected cases are currently under investigation to determine if they meet the criteria for probable cases of West Nile virus.
Of the six probable cases, two are Assiniboine Regional Health Authority residents, two are Interlake Regional Health Authority residents, and one resides in each of the Winnipeg Regional Health Authority and Central Regional Health Authority areas. The likeliest locations of exposure for the six probable cases are Deloraine, Arborg, Winnipeg Beach, Morris, Winnipeg and the R. M. of Turtle Mountain. Further information on human cases will be posted on the website when it becomes available.
So far this year, 1,124 people have been tested for WNV in Manitoba.
Based on mosquito surveillance data from the week of Aug. 7 to 13 that indicates a lower risk to human health, adult mosquito control under a ministerial order has been put on hold in the city of Winnipeg, the city of Winkler, the town of Carman, the R.M. of West St. Paul and the R.M. of East St. Paul. While current data indicates a lower risk to human health, the risk may still rise in the coming weeks. For this reason, the ministerial orders are still in place, even though there are no immediate plans for fogging at this time.
Now and throughout the month of August, the importance of taking personal protective precautions against mosquitoes continues. As daytime and evening temperatures become cooler, Culex tarsalis mosquitoes may become more active during the day as well as between dusk and dawn. Lower evening temperatures reduce the opportunities for and effectiveness of adult mosquito control (fogging).
Manitobans can reduce the risk of mosquito bites by:
reducing the amount of time spent outdoors whenever mosquitoes are active,
using appropriate mosquito repellent, and
wearing light-coloured, loose-fitting clothing.
At this time, 28 communities in Manitoba have had West Nile virus positive mosquito samples. Mosquito samples have tested positive for WNV 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, Russell, Stony Mountain, Winnipeg and West St. Paul. During the week of Aug. 7 to 13, positive mosquito samples were identified in Beausejour, St. Andrews, Neepawa and Sandy Bay First Nations for the first time this season.
During the week of Aug. 7 to 13, average Culex tarsalis trap counts increased in the Assiniboine, Parkland and North Eastman regional health authorities. Weekly average counts in all other regional health authorities decreased from the previous week.
Surveillance 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.
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. No further birds are required for testing from southern Manitoba.
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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