Hamilton confirms its 1st human case of West Nile Virus in 2023

Hamilton's first human case of West Nile Virus (WNV) of 2023 has been confirmed, prompting the local medical officer of health to move the risk of the virus from moderate to high, the city said on Tuesday.

The city provided no specific details about the case.

Hamilton is now among several cities in the province to report a probable human case in recent weeks, including London and Toronto.

The virus is an annual concern for public health officials in southern Ontario. 

Eighty per cent of people who become infected with West Nile Virus do not get sick, and fewer than one per cent become seriously sick, with the majority of those who experience symptoms seeing mild flu-like symptoms, according to public health officials.

The virus is transmitted through the bite of an infected mosquito and symptoms could include:

• Fever.
• Headache.
• Nausea.
• Vomiting.
• Body aches.
• Skin rash.
• Swollen lymph glands.

For any infection, if symptoms do occur, they appear two to 14 days after being bitten by an infected mosquito, the city says.

In a news release, the city reminded residents to protect themselves against mosquito bites and to remove standing water from private property to prevent mosquito breeding.

"It is important to take precautions to avoid illnesses spread by insects including West Nile Virus, Lyme disease, and Eastern equine encephalitis," associate medical officer of health Dr. Bart Harvey said.

"Employing simple preventive measures such as using insect repellent containing DEET or Icaridin, covering up, and removing standing water on your property to prevent mosquito breeding will reduce your risk while you enjoy the outdoors. The risk of these infections will drop once there is a heavy frost that reduces the number of mosquitoes."

The city says Hamilton Public Health Services continually assesses the risk for human illness as part of a comprehensive West Nile Virus surveillance and prevention program. 

Meanwhile, the city says it has completed three rounds of larviciding treatments on city street catch basins, in addition to treatment of surface waters on public land.