West Nile virus detected in mosquitoes in Brantford and St. Catharines, Ont.

West Nile virus has been found in mosquitoes in Brantford, Ont., and St. Catharines, Ont. for the first time this year, according to the local public health agency. 

A July 19 press release from the Brant County Health Unit states mosquitoes with the virus were detected in a Brantford neighbourhood.

Niagara Region Public Health shared news of the mosquitoes in St. Catharines on Monday.

There have been no human West Nile cases identified in Brantford, Brant County or Niagara Region, according to local health authorities.

Gillian Dilts, who manages Niagara public health's vector-borne and zoonotic disease program, said the infected mosquito in St. Catharines was found in one of the traps the department puts out in each of the 12 municipalities it services as part of its West Nile virus surveillance program.

It's working with a third-party company to kill mosquito larva in catch basins on roadsides, Dilts said. Mosquitos typically breed in standing water. 

Residents are encouraged to help reduce potential breeding sites by limiting the amount of standing water on their properties, including covering rain barrels with fine mesh.

Filip Pajtondziev, a manager of infectious diseases with Brant County Health Unit, said in a media release the rainfall and high temperatures this summer are creating good breeding ground for mosquitoes.

Virus detected in other regions

Mosquitoes with West Nile have been found in Peel Region, as well. Ottawa Public Health, meanwhile, confirmed a first human case of West Nile.

In 2023 there were 54 confirmed cases across Ontario, with eight confirmed cases in the Niagara region, Dilts said.

Windsor Morning7:21There are 50 species of mosquitoes in Ontario. Here's how to keep them away.

Fiona Hunter a medical and veterinary entomology professor at Brock University who studies all flies that bite.

West Nile virus is primarily spread by the northern house mosquito. 

Only a small number of people bitten by a mosquito carrying the virus will become infected.

About 20 per cent of those infected may experience flu-like symptoms including fever, headache, muscle aches and a rash.

Dilts said people who are immunocompromised are at a greater risk of developing West Nile virus or having more severe infections.

"We always recommend ... speaking to a healthcare provider so that they can assess those symptoms and undertake any testing for West Nile virus," she said.

To avoid mosquito bites, Niagara public health recommends: 

• Wearing long-sleeved shirts, long pants, socks and shoes when outdoors.
• Using mosquito repellent containing DEET or Icaridin, and carefully follow the manufacturer's directions.
• Draining areas of standing or stagnant water on your property regularly, including bird baths, old tires, pails, toys and wheelbarrows.
• Ensuring all windows and doors in your home have screens that are in good condition.