An adult who tested positive for West Nile virus is the first confirmed case of the virus in Toronto in 2019, Toronto Public Health says.

The health agency did not say where or when the person contracted the virus but is now warning residents to take the proper precautions through the end of summer to avoid being bitten by mosquitoes.

West Nile virus symptoms typically develop between two and 14 days after a person is bitten by an infected mosquito. 

Symptoms may include fever, headache, nausea, vomiting, body aches, skin rash and swollen lymph glands.

"As we head into late summer, we know that residents and visitors to Toronto are maximizing their time outside to enjoy the weather and outdoor activities,” Doctor Eileen de Villa, Toronto's Medical Officer of Health, said in a statement. 

“We encourage everyone to take the appropriate precautions to minimize the risk of exposure to West Nile virus through the bite of an infected mosquito."

In 2018, there were 39 laboratory-confirmed human cases of West Nile virus and 40 positive mosquito tests reported to Toronto Public Health.

Toronto Public Health advises residents to take these precautions to avoid bites from infected mosquitoes: 

  • Wear light-coloured clothing, long pants and long-sleeved shirts when outdoors
  • Apply insect repellent containing DEET or icaridin and follow the manufacturer's instructions
  • Take extra care during peak mosquito-biting hours, dusk and dawn, by using repellent and covering up
  • Make sure your home has tight-fitting screens on windows and doors.
  • Remove standing water from your property, where mosquitoes can breed. Standing water includes any water that collects in items such as buckets, planters, toys and waste containers