Ontarians are being asked to grab some insect repellent to combat West Nile virus, which officials say is on the rise in mosquito pools across the province.

Forty-three mosquito pools infected with the West Nile virus have been discovered in Ontario so far this year, the highest reported over the last four years, according to the Ministry of Health. That number does not include a report from the Regional Municipality of York on the area's first positive West Nile virus mosquito tests.

According to a press released published Friday, three mosquito pools in the Town of East Gwiillimbury and in the Town of Markham tested positive for the virus. The region said treatment of the catch basins as well as the necessary treatment of surrounding stagnant water on public property is underway.

In a statement released Thursday, Ontario's Chief Medical Officer of Health asked people across the province to be on high alert against the blood-sucking insects.

Dr. Arlene King advises Ontarians to:

  • Wear light-coloured clothing, long-sleeved shirts, long pants, socks and shoes while outdoors.
  • Use insect repellent containing DEET
  • Avoid going outside at dusk and dawn when mosquitoes are most active
  • Replace or repair screens on windows to prevent mosquitoes from entering your home.
  • Drain pools of standing water around your home

Those who contract West Nile virus might experience fever, body ache, nausea, vomiting and rashes. It's possible for muscle weakness, tremors and numbness to develop in more serious cases.

Infected individuals typically experience symptoms two to 15 days after being bitten by a West Nile-positive mosquito.

Only one travel-related case of West Nile virus has been reported in a human this year.