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Mosquitoes and West Nile Virus

A bite from an infected mosquito can cause an illness, such as West Nile virus (WNv). Infected mosquitoes can spread the virus to humans and other animals. West Nile virus is not currently a widespread illness in Northeastern Ontario; however, there is a possibility that, with changes in climate and migration, the mosquitoes that are capable of causing illness could one day be a greater concern.


The best way to avoid becoming infected with West Nile virus is to prevent mosquito bites. Here are things you can do:

  • When you are outside, wear light-coloured clothing, closed-toe footwear, socks, and long-sleeved tops and pants.
  • When you are outside, use insect repellent that has DEET or Icaridin on clothes and exposed skin (avoiding eyes and mouth). Be sure to follow the manufacturer’s directions.
  • Limit your time outdoors during dawn and dusk when mosquitoes are most active.
  • Repair holes in screens, windows, and doors.
  • Maintain areas where mosquitoes are most likely to lay their eggs:
    • Change water in bird baths every other day;
    • Keep pool pumps and pumps in ornamental ponds circulating;
    • Cover openings in rain barrels; and
    • Empty standing water regularly from:
      • Clogged eavestroughs and gutters,
      • Garbage cans,
      • Flowerpots and saucers,
      • Wheelbarrows,
      • Pool covers,
      • Wading pools,
      • Toys, and
      • Old tires.

Signs and Symptoms

Most people who are bitten by an infected mosquito will not necessarily experience symptoms. If symptoms do develop, they are usually mild and typically start between 2-15 days after being bitten. Common symptoms can include: 

  • Fever;
  • Headaches;
  • Body aches;
  • Nausea;
  • Vomiting; and/or
  • Mild rash.

A small percentage of people may become seriously ill. Young children, older adults, those who have chronic diseases, and those with weakened immune systems are at a higher risk of serious health effects. Symptoms may include:

  • Severe headaches;
  • Muscle weakness;
  • Confusion;
  • Tremors;
  • Numbness; and/or
  • Sensitivity to light.

It is recommended to seek medical attention if you are feeling unwell.


During the summer months, the Porcupine Health Unit conducts a mosquito monitoring program that includes mosquito trapping and testing throughout the district.

In our region, the risk remains low for the West Nile virus. In the Fall of 2019, the health unit received a report of a bird found within the region that tested positive for WNv. Prior to this, the last positive bird reported in our area was in 2006. The last positive mosquito pool in our area was also reported in 2006.

For the most up-to-date information about how to protect yourself, please refer to Public Health Ontario’s webpage for West Nile virus.

If you have questions or concerns about West Nile virus, contact a Public Health Inspector at 705-267-1181 or 1-800-461-1818.