Local West Nile Virus Surveillance

Staff of the health unit continued to conduct West Nile surveillance activity during the 2002 mosquito season. These activities included the following: mosquito trapping, speciation and submission to the laboratory for WNV identification, enhanced human surveillance, assessment of dead bird reports and the continual identification of mosquito breeding areas within the tri-county area. 

In July of this year the first of 4 positive birds (all crows) was found positive for West Nile Virus in the Tri-county area. The locations of these dead birds were evenly distributed throughout the health unit area. Due to extensive workload at the Central Laboratory in Winnipeg, we were requested not to submit any further birds for analyses until their workload subsided. The rationale for this action was that any health unit where two or more positive birds were identified, it was assumed the finding of any subsequent dead birds could be presumed to be also positive for West Nile Virus. 

Also in July, all municipalities received updated maps indicating actual or potential mosquito breeding areas within their respective municipalities. Each municipality was requested to voluntarily undertake some source reduction in certain identified mosquito breeding areas. As a result, some municipalities have pursued source reduction through re-grading of identified ditches, reducing areas where water can pond over extended periods of time or flushing of storm sewers, etc. To date, all the mosquitoes that have been sent from our district to the laboratory for West Nile Virus analysis have been negative.

The locations of these dead birds were evenly distributed throughout the health unit area.