West Nile Virus Activity Reported in Listowel

Huron Perth, ON – Huron Perth Public Health (HPPH) reminds residents to protect themselves against mosquito bites following confirmation that mosquitoes collected from a trap in Listowel have tested positive for West Nile virus (WNV). These are the first WNV positive mosquito findings of the season for Huron and Perth counties. 

“It’s not surprising to see West Nile virus positive mosquitoes in the month of August,” says Dale Lyttle, senior public health inspector. “In the late summer months, people are at greatest risk of contracting West Nile virus, so it is important to protect yourself while outdoors when mosquitoes are most active,” he adds. 

Mosquito Surveillance and Control Activities 

As part of annual mosquito surveillance, HPPH has been trapping and testing mosquitoes in locations across Huron and Perth since June 15, 2026. Where WNV positive mosquitoes have been istorically identified, larvicide is applied to roadside catch basins over the summer months to reduce mosquito breeding. These sites include Stratford, St. Marys, Listowel and Mitchell.  

West Nile Virus in Humans 

In Ontario, five confirmed human cases of WNV have been reported in the 2026 season. Not everyone who is bitten by an infected mosquito will show symptoms of the virus. Of those who do show symptoms, most will experience mild illness, including fever, headache, body aches, nausea, vomiting and rash on the chest, stomach or back. About one in 150 people infected will get seriously ill, with symptoms like high fever, muscle weakness, vision loss, and coma. WNV can lead to death. 

Symptoms usually develop between two and 15 days after being bitten by an infected mosquito. People older than 50 and those with weakened immune systems are at higher risk for severe illness due to WNV infection.  

Protect Yourself from Mosquito Bites 

• People can protect themselves from mosquito bites by: 
• Using an insect repellent containing DEET or Icaridin when outdoors. Be sure to follow the manufacturer’s directions. 
• Covering up with light-colored clothes, long sleeves and pants when outdoors or in areas where mosquito activity is high. 
• Taking extra protection measures at dusk and dawn when mosquitoes are most active. 
• Removing standing water around the home at least once a week to reduce mosquito breeding grounds.