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West Nile Virus Found in Mississauga mosquitoes: what you need to know

Residents are urged to follow these tips to reduce risk from virus-carrying mosquitoes.

City services | July 25, 2025

West Nile virus has been confirmed in Peel Region. With the virus now active locally, residents are advised to take immediate steps to protect themselves (and their property) from infected insects.

What is West Nile virus?

West Nile virus is a mosquito-borne illness that can cause mild flu-like symptoms in most people, but in rare cases, it can lead to serious illness affecting the brain or nervous system. There is no vaccine or specific treatment for humans, making prevention essential. People more than 50 or with weakened immune systems are at higher risk for serious complications.

Tips to protect yourself from mosquito bites

Mosquitoes that transmit West Nile virus are most active at dusk and dawn. Limit exposure during peak mosquito hours or, if possible, stay indoors during these times.

Applying effective insect repellents containing DEET or icaridin when outdoors is also recommended. Other tips to keep in mind include:

• Wear protective clothing. Dress in long sleeves, pants, socks, and a hat when outside, especially at dawn and dusk.
• Light-coloured, loose-fitting clothing is best, as mosquitoes are attracted to dark colours.
• Special clothing and camping gear treated with permethrin can help when spending extended time outdoors (never apply permethrin directly to skin).

How to mosquito-proof your property

Mosquitoes lay eggs in stagnant water, turning even tiny amounts of water into breeding sites. Community mosquito control (such as the Region’s larvicide program) helps reduce risk, but residents must also take proactive steps.

Mosquitoes need only a few millimetres of stagnant water to breed. To help prevent the spread of West Nile virus, do your best to eliminate standing water on your property.

Empty and scrub standing water sources at least once a week, including:

  • Birdbaths
  • Flowerpots and saucers
  • Kiddie pools and toys
  • Old tires
  • Outdoor pet bowls

Preventive measures

Other preventive steps include ensuring all windows and door screens fit securely and are free of tears and holes. It is also important to store any water-catching items indoors or under cover and repairing leaking outdoor hoses or faucets to prevent small puddles from forming. If you notice persistent standing water in local catch basins, ditches, or other public areas, report it to Peel Public Health by dialing 905-799-7700 (or toll-free at 1-888-919-7800) or online.

The risk of contracting West Nile virus is low but rises as mosquito counts increase in summer. By following these recommendations, you can dramatically reduce your risk and help protect your community.

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