August 4, 2007
West Nile Virus Bulletin #4
The first human death related to a West Nile virus infection of a person in Manitoba in 2007 has been identified.
The person, a male in his 80s, was a resident of the Assiniboine health region and had contracted the more severe type of West Nile virus disease (West Nile virus neurological syndrome). Based on public health investigations to date, it is likely that West Nile virus was the cause of death and the patient had no known underlying medical conditions. The likeliest area where the person was exposed to West Nile virus is under investigation.
To protect the personal health information of this individual, further details about this individual will not be released.
The year 2003 was the first year human cases of West Nile virus were reported in Manitoba. Including this case, there have been four reported deaths related to West Nile virus since 2003 in Manitoba.
The number of cases of the more severe type of West Nile virus (West Nile virus neurological syndrome) in previous years has ranged from one to 35 cases per summer. Between 2003 and 2006, 63 cases of West Nile virus neurological syndrome have been reported in Manitoba.
To date this year, a total of 42 positive test results for West Nile virus have been reported in Manitoba. Thirty-eight test results were identified through clinical testing at Cadham Provincial Laboratory. Four test results were identified through Canadian Blood Services routine screening and the donated blood units were discarded according to plan.
Additional information on human cases including classification of disease (West Nile neurological syndrome, West Nile non-neurological syndrome or asymptomatic), decade of age, gender, regional health authority of residence and likeliest area of exposure, as well as information on adult mosquito control schedules will be provided on the website when it becomes available at https://www.gov.mb.ca/health/wnv.
In comparison to previous years, this has been the earliest in the summer season for reports of positive human test results and a death from West Nile virus in Manitoba. In comparison to previous years, trap counts of Culex tarsalis mosquitoes infected by West Nile virus in Manitoba are, on average, higher and earlier in the summer season than ever before.
The chief medical officer of health continues to encourage Manitobans to 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
· maintaining door and window screens so they fit tightly and are free of holes.
Manitobans are advised to reduce mosquito numbers near their homes and in their communities by reducing standing water. To reduce the development of Culex tarsalis mosquitoes:
· clean eavestroughs;
· at least once a week, empty bird baths and other items that might collect water;
· cover rain barrels with mosquito screening or maintain tight seals around downspouts; and
· dispose of old tires or other debris that collect water.
For more information on West Nile virus in Manitoba, visits the province’s West Nile virus website at https://www.gov.mb.ca/health/wnv or call Health Links–Info Santé at 788-8200 or 1‑888‑315-9257.
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