Report of season’s first positive mosquito pools for West Nile Virus

Durham Region Health Department has received notification of adult mosquitoes that have tested positive for West Nile virus (WNV). The two separate positive mosquito pools were collected on Aug. 7 from one of the Health Department’s permanent mosquito trap sites located in Ajax. Positive confirmation was received on Aug. 9. These are the first mosquitoes in Durham Region to test positive for WNV this season.

“With this West Nile-positive mosquito result, it’s important for area residents to take precautions to avoid mosquito bites and remove standing water from their properties,” said Ross MacEachern, Manager, Health Protection with the Health Department.

WNV is a mosquito-borne disease that is spread to humans via the bite of an infected mosquito. Mosquitoes become infected by feeding on the blood of a bird that carries the virus. The disease is not passed from person to person or from bird to person. Most people who contract the virus will experience mild illness including fever, headache, body ache, nausea, vomiting, and rash on the chest, stomach or back. More serious symptoms can include muscle weakness, stiff neck, confusion, tremors, numbness and sudden sensitivity to light. Symptoms usually develop between two and 15 days after being bitten by an infected mosquito.

Although the risk of becoming infected is low, residents should still take the following precautions to minimize the risk of mosquito bites and the possibility of being infected with WNV:

  • Wear shoes, socks and light-coloured clothing, including long sleeve tops and full-length pants, when outside especially at dusk or dawn when mosquitoes are most active.
  • Use insect repellent containing DEET or Icaridin on exposed skin, following Health Canada’s safety tips on using personal insect repellents.
  • Remove standing water from your property where mosquitoes can breed.
  • Ensure that window and door screens are in good repair to prevent mosquitoes from entering your home.

Durham Region Health Department sets mosquito traps across the region and submits mosquitoes for laboratory testing every week between June and September. In addition, regional catch basins and other stagnant water sites are treated with a larvicide to reduce mosquito breeding. For more information on WNV, please call the Health Department’s Environmental Help Line at 905-723-3818 or 1-888-777-9613, or visit

Leave a Reply

Your email address will not be published. Required fields are marked *

Share This