First human case of West Nile virus confirmed in Huron Perth

Huron Perth Public Health (HPPH) is urging residents to take precautions against mosquito bites after confirming the region’s first locally-acquired human case of West Nile virus in 2025.

It comes one month after mosquitoes collected from traps in Listowel and Mitchell tested positive for the illness.

“While the overall risk to the public remains low, this is a timely reminder that West Nile virus activity typically increases in late summer and early fall,” Dr. Lauren Hayward, a physician consultant at HPPH, said in a media release. “We encourage residents to take precautions to protect themselves from mosquito bites. If you are spending time outdoors at dawn and dusk, when mosquitos are most active, use insect repellent and wear long sleeves and pants.”

Five Halton residents also tested positive for West Nile virus on Monday. They were also the first human cases reported in Halton Region this year.

What is West Nile virus?

The West Nile virus could potentially cause death.

It is primarily transmitted to humans by mosquitoes that have fed on an infected bird. There is no human-to-human transfer of the illness.

Most people who get the virus experience no symptoms. Others may get a fever, headache, body aches, mild rash and swollen lymph glands. Recovery can take about a week.

In the most serious cases, it can cause a severe headache, high fever, stiff neck, nausea, vomiting, trouble swallowing, drowsiness, confusion, loss of consciousness, lack of co-ordination, muscle weakness or paralysis. These can last months or even years after infection.

According to Health Canada, less than one per cent of people will develop severe symptoms that affect the central nervous system.

West Nile Virus in humans

According to Public Health Ontario, there have been 61 confirmed human cases across the province so far this year. Most people bitten by an infected mosquito will not experience symptoms, but those who do may get a fever, headache, nausea, body aches and rashes. In rare cases — about one in 150 infections — the virus can lead to serious illness or even death.

Mosquito surveillance and control

HPPH said its mosquito surveillance program identified positive mosquito pools in August. Officials targeted their breeding grounds using larvicide in Stratford, St. Marys, Listowel and Mitchell.

Protecting against the virus

Residents are advised to wear insect repellent containing DEET or Icaridin, wear light-coloured clothing, cover up with long sleeves and pants and remove standing water around their homes. Extra caution is recommended at dawn and dusk, when mosquitoes are most active.