Mosquitoes in Markham test positive for West Nile virus

Two mosquito traps in the City of Markham have tested positive for West Nile virus, leading York Region Public Health to offer tips on how to protect yourself and your family from mosquito bites.

The two traps that tested positive – the first positive traps reported in York Region this summer – are located at Warden Avenue and Hwy. 7 East and at Kennedy Road and 16th Avenue.

York Region Public Health monitors West Nile virus activity by setting mosquito traps and testing for West Nile virus, which is an infection that can be spread to people through the bite of an infected mosquito.

To protect yourself and your family from mosquito bites and West Nile virus, get rid of mosquito-friendly areas at home. Clean up standing water from your property where mosquitos can breed, such as bird baths, flowerpots, swimming pool covers and clogged eavestroughs. Ensure window screens in your home are tight-fitting and in good repair. York Region Public Health also recommends covering up while outside. Use insect repellent containing DEET or icaridin according to manufacturer’s instructions and wear light-coloured protective clothing, including pants and long-sleeved shirts.

One of the measures to control West Nile virus is to reduce mosquito populations through a process called larviciding, which involves using pesticides (larvicides) to control mosquitoes when they’re in the larval stage of development. This stage occurs in water, after the mosquito eggs hatch, but before the mosquito becomes an adult that bites.

York Region conducts mosquito surveillance from mid-June until the end of September every year. Confirmed and suspected human cases of West Nile virus illness are reported to York Region’s Medical Officer of Health and investigated by York Region. As part of the Region’s 2026 West Nile virus Control Plan, York Region Public Health uses larvicides in catch basins to control mosquito breeding along regional and municipal roads and other stagnant public water sources, including roadside ditches, monitors mosquitoes for West Nile virus weekly and investigates reported human cases.

Watch the Fight the Bite video to learn more about symptoms and how to protect yourself from West Nile virus. For more information on West Nile virus, contact York Region Health Connection at 1-800-361-5653 or TTY 711 or visit york.ca/WestNile.