West Nile Virus Positive Mosquitoes Found in Stratford


Tuesday, August 29, 2017


Perth County ― Tests on mosquitoes taken from a trap located in the northeastern part of Stratford have come back positive for West Nile virus (WNV). This brings the number of positive mosquito pools to six in Perth County this season.


So far in 2017, 264 WNV-positive mosquito pools have been found in Ontario. A mosquito pool is a group of female mosquitoes belonging to the same species. As part of its WNV monitoring efforts, the Perth District Health Unit has been trapping and testing mosquitoes in Stratford, St. Marys, Listowel and Mitchell since June. To help reduce mosquito breeding, they have also applied two rounds of larvicide in roadside catch basins in these same communities.


“With this latest result, traps in all four communities have had mosquito pools positive for WNV,” says Stephanie Carlisle, Public Health Inspector. She adds, “this is a good reminder to residents to take precautions against mosquitoes.” The risk of humans getting sick with WNV is highest this time of year. Currently, there are no human cases in Perth County. In Ontario, there have been 14 reported (confirmed or probable) human WNV cases; two were travel-related.


Not everyone who is bitten by an infected mosquito will show symptoms. Of those who show symptoms, most will experience mild illness, including fever, headache, body aches, nausea, vomiting, and/or rash on the chest, stomach or back. About one in 150 people infected will become seriously ill, with symptoms like high fever, muscle weakness, vision loss and coma. People over the age of 50 are most at risk for WNV infection, as are those with weakened immune systems. Symptoms typically develop between two and 15 days after being bitten by an infected mosquito.


Mosquitoes are usually active until the first hard frost. The Health Unit is asking residents to protect themselves from mosquito bites by:

  • Removing standing water around the home at least once a week to reduce mosquito breeding grounds.
  • Using insect repellent when outdoors; a repellent with DEET or Icaridin offers the most effective protection.
  • Covering up with light-coloured clothes, long sleeves and pants when outdoors or while in areas where mosquito activity is high.
  • Taking extra protection measures at dusk and dawn when mosquitoes are most active.


For more information:

  • Call Health Line at 519-271-7600 extension 267 or toll-free at 1-877-271-7348 extension 267
  • Visit www.pdhu.on.ca.
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