September 08, 2005
Since last week’s update, nine more Manitobans have tested positive for West Nile virus. This brings the total number of Manitobans who have tested positive for West Nile virus this year to 42.
Following investigations by public health officials, 32 human cases have been classified at this time.
Nine are probable cases of West Nile neurological syndrome. Seven of these individuals were admitted to hospital and two remain in hospital.
Twenty are classified as probable cases of West Nile non-neurological syndrome. These individuals did not require hospitalization.
Three are confirmed as asymptomatic cases of West Nile virus. These cases were identified by Canadian Blood Services. The individuals did not show symptoms.
The remaining 10 cases are currently under investigation to determine their status.
The first human death related to West Nile virus infection in Manitoba this year was reported on Aug. 31. The role West Nile virus played in this death is still under investigation.
The 32 classified cases reside within the boundaries of seven regional health authorities in southern Manitoba:
Winnipeg Regional Health Authority – 10;
Assiniboine Regional Health Authority – nine;
Central Regional Health Authority – seven;
Interlake Regional Health Authority – two;
South Eastman Regional Health Authority – two;
Brandon Regional Health Authority – one; and
North Eastman Regional Health Authority – one.
Further information on human cases will be posted on the website when it becomes available. Most of these human cases reflect exposures to West Nile virus infected mosquitoes during July and the first half of August. So far this year, 1,730 people have been tested for WNV in Manitoba.
Current mosquito surveillance in southern Manitoba indicates the activity of Culex tarsalis, the main mosquito species that carries West Nile virus in Manitoba, was low in all regional health authorities during the week of Aug. 28 to Sept. 3.
Two West Nile virus positive mosquito samples were identified during the week of Aug. 28 to Sept. 3 in the Winnipeg and South Eastman regional health authorities.
Routine trapping for adult mosquitoes will end this week in most communities. As weather conditions are favourable, monitoring of adult mosquitoes will continue in some communities in southern Manitoba.
While the risk of exposure to infected mosquitoes is decreasing, mosquito surveillance shows there are still small numbers of infected mosquitoes in southern Manitoba. During early September, the importance of taking personal protective precautions when mosquitoes are active continues.
As daytime and evening temperatures become cooler, Culex tarsalis mosquitoes and other mosquitoes may become more active during the day as well as between dusk and dawn. Manitobans can reduce the risk of mosquito bites by:
checking that door and window screens fit tightly and are free of holes;
reducing the amount of time spent outdoors whenever mosquitoes are active;
wearing light-coloured, loose-fitting clothing; and
using appropriate mosquito repellent.
Public information about West Nile virus 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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