Toronto Public Health and the Canadian Centre of Mosquito Management have kicked off their offensive against the city’s mosquito population in an effort to control the spread of West Nile Virus.

The potentially deadly virus is spread from dead birds to mosquitoes who can in turn infect humans.

Last summer one man died and 12 others were infected with the virus in Toronto. In 2012, 94 cases were reported and one person died, according to Toronto Public Health.

Though officials have no way of knowing for sure how severe the season will be, the cold winter and relatively cold spring point to a milder risk if the weather trends continue, according to Dr. Howard Shapiro, Toronto Public Health’s associate medical officer of health and director of health environments.

“But I don’t know what’s going to happen. We’ve had other years when it looks really bad, and all of a sudden the weather changes,” said Dr. Shapiro, referring to 2005 when high temperatures were contributing to what looked like a severe season, but a large August storm washed away larvae and temperatures cooled for the rest of the summer.

The city’s health department and the Canadian Centre of Mosquito Management team up to provide monitoring and control efforts, including trapping and testing mosquitoes to monitor the virus levels and spreading larvicide in 120,000 catch basins across Toronto to kill off potentially lethal pests.

Four out of five people infected with the virus don’t display any symptoms, while one in five infected people will feel the sickness but can recover on their own.

Less than one per cent of people infected with the virus need to be hospitalized.

Symptoms include fever, headaches, nausea, vomiting and body aches and potentially skin rashes and swollen glands. These symptoms cans last a few days to weeks.

One in 150 people infected can experience more severe symptoms, including neck stiffness, extreme confusion, disorientation, muscle weakness, vision loss and numbness.

The risk of contracting the virus increases around age 55, even in healthy adults, said Dr. Shapiro, while children are relatively spared the severe consequences of infection.

“I usually tell people be more worried about your parents than your children,” he said.

Toronto Public Health offers these tips for avoiding mosquito bites in the first place:

  • Stay indoors during peak mosquito activity (at dusk and dawn)
  • Wear light-coloured clothing, long pants, long-sleeved shirts, socks and a hat.
  • Use mosquito repellent approved by Health Canada
  • Make sure your home has tight-fitting screens on windows & doors.
  • Avoid areas with large numbers of mosquitoes

Toronto Public Health also recommends keeping private property clear of standing water. They suggest homeowners keep eaves and gutters clear, dump built-up water from bird baths and garden toys, keep an eye on pools and ponds, and check around hoses and faucets for pools of water.