West Nile Virus

West Nile virus (WNV) is mostly a disease that affects birds. However, it can be spread to humans by mosquitoes that feed on both birds and humans. Not all mosquitoes carry the WNV.

WNV surveillance activities

2025 weekly adult mosquito surveillance results in Durham Region

West Nile Virus in Durham Region infographic

Protect yourself against West Nile virus

About 70 per cent to 80 per cent of infected people with WNV do not develop any symptoms. For those who do develop symptoms, they will usually appear within 2 to 15 days after infection.

Mild symptoms include:

  • Headache
  • Body aches
  • Joint pains
  • Vomiting
  • Diarrhea
  • Rash

Less than one per cent of people who are infected may develop meningitis or encephalitis (swelling of the brain). Ten per cent of people who develop neurologic infection die.

Severe symptoms include:

  • severe headache
  • high fever
  • stiff neck
  • nausea and/or vomiting
  • trouble swallowing
  • drowsiness
  • confusion

Diagnosis

A diagnosis of WNV is based on symptoms and a known exposure to mosquitoes.

Testing

Blood or spinal fluid testing can be used to confirm WNV infection.

Treatment

There is no vaccine or specific treatment for WNV infection. You can use over-the-counter pain relievers to reduce fever and relieve some symptoms. In severe cases, patients may need to go to the hospital to get treatment. This could include:

  • Intravenous (IV) fluids
  • Pain medication
  • Nursing care

The most effective way to avoid WNV infection is to prevent mosquito bites. Be aware of the West Nile virus activity in your area. Take action to protect yourself and your family.

You can reduce your risk of being infected with WNV by using insect repellent, wearing protective clothing to prevent mosquito bites, and eliminating stagnant water on your property.

A bite of an infected mosquito spreads WNV.

WNV cannot spread from animal-to-person contact. West Nile virus cannot generally spread from person to person.

The Durham Region Health Department conducts surveillance and control activities for WNV. These include:
  • Larviciding roadside catch basins.
  • Larviciding stagnant surface water sites.
  • Trapping adult mosquitoes and sending them in for identification and testing.
  • Investigating human cases of WNV disease.

Online services

Residents

Durham Region Health Department investigates reports of stagnant water on publicly owned property and facilitates the application of larviciding to backyard catch basins to reduce the breeding of mosquitoes for the prevention of the spread of West Nile virus.

Report a stagnant water issue on publicly owned property Apply for backyard catch basin larviciding

Residents can report stagnant water on private property by contacting their local municipal by-law office.

Ajax | Brock | Clarington | Oshawa | Pickering | Scugog | Uxbridge | Whitby


Municipal by-law enforcement officers

Submit a stagnant water complaint referral