Canada is reporting its first deaths from the West Nile virus this year after two Toronto men died from the mosquito-born disease.

Over the weekend, two men died from the virus, which is carried by birds and transmitted to humans by mosquito bites. One of the victims was 63 years old and the other was 90.

Both men had a severe strain of the virus, and their deaths were linked directly to it; in many cases, the virus is just a contributing factor to death along other medical conditions.

Health officials believe both men were infected in late July or early August.

Experts believe the hot, humid weather in the Toronto area this summer has contributed to the problem.

"The virus has had an opportunity to amplify and replicate itself mostly in the bird population and the mosquito population," Dan Kartzalis, manager of Toronto Public Health's West Nile program, told CTV Toronto News.

"It's really important to tell people they're at risk for West Nile virus," Dr. Michael Finkelstein, Toronto's associate medical officer of health, said in an interview.

"It's rare to have severe symptoms due to the virus, and that's important to note. But the risk period is right now."

Finkelstein said there could be more cases to come, and people should be taking precautions to avoid mosquito bites.

"In the past, we have seen more cases reported to us in September, and that's why it's important to tell people that the risk for West Nile virus is still here."

Health officials advise wearing light-coloured clothing, using mosquito repellent and fixing holes in door and window screens.

The West Nile virus was first detected in Toronto in 2002, when 10 deaths were reported. There were no deaths from the virus in either of the following two years.