Virus numbers on upswing, officials begin testing
The Windsor-Essex County Health Unit has begun its annual West Nile virus prevention program after last year saw increases in the number of mosquito pools that tested positive for the virus and the number of confirmed human cases. “I wouldn’t use the word ‘alarm.’ I would say it is a concern,” said Dr. Wajid Ahmed, the region’s acting medical officer of health. “People need to be taking precautions.” According to the health unit’s records, 29 mosquito pools tested positive for the West Nile virus in 2017 — up from just one in 2014. Twenty human cases of West Nile virus were reported and confirmed in 2017 — compared to just one in 2014.
“The numbers fluctuate every year,” Ahmed said. “It’s hard to say by one year if they’re going in the right or wrong direction.”
For example, there were 22 reported human cases of West Nile virus in 2012, but only five the following year.
Ahmed also noted that more mosquito pools were tested for the West Nile virus last year than in previous years — 631 in 2017 compared to 411 in 2014. Seasonal weather trends also affect mosquito numbers. Higher temperatures and rainfall can lead to a busy mosquito season. On Tuesday, the health unit launched its yearly West Nile virus prevention program by having a contracted service provider begin surveillance of adult mosquitoes. Traps set out on private properties across the region will check for the presence of the common mosquito species known to carry the West Nile virus: Culex pipiens, Culex tarsalis, and Culex quinquefasciatus.
Later this week, traps will be set for Aedes albopictus and Aedes aegypti — the invasive Asian tiger and yellow fever mosquitoes that can also carry the West Nile virus. Adult specimens or larvae of both invasive species were found in Windsor traps last summer. In the coming weeks, the program will proceed with larviciding of catch basins, standing water sites, and lagoons — meant to disrupt mosquito breeding.
The health unit will also be increasing efforts to educate the public on protection against West Nile virus and investigating suspected human cases.
“The majority of West Nile virus cases are asymptomatic; they don’t show any symptoms at all,” Ahmed said. “Very rarely some of them end up going to hospital for further treatment.”
If you know you will be in places prone to bugs, insect repellents can keep mosquitoes at bay. The health unit advises use of repellents that contain approved active ingredients such as DEET or Icaridin. The repellents work best when applied to clothing as well as exposed skin.
Light colours are recommended, as mosquitoes are attracted to dark colours. Mosquitoes are also drawn to body odours, perfumes, colognes, and even the carbon dioxide in your exhalations. Longsleeved shirts, long pants, and hats should be worn.
“Try to avoid those times when mosquitoes are most active — the early morning or the early evening,” added Mike Tudor, a manager of environmental health with WECHU. Residents should ensure that their outer doors and window screens fit securely to keep mosquitoes from entering their living spaces. But the best measure is to eliminate standing water on properties, since mosquitoes can breed anywhere that water collects: old tires, wheelbarrows, animal dishes, bird baths, flower pots, and more. For more information about West Nile virus in Windsor-Essex, visit wechu.org/your-environment/west-nile-virus.