The West Nile virus returned to Canada for another season when mosquitoes were detected in multiple regions of Ontario last week, including Toronto.
Public Health in the Niagara Region confirmed Tuesday that the West Nile virus was detected in mosquitoes in Welland, Ontario, while the Toronto and York regions reported their first positive cases of insects last weekend.
As of Wednesday, no human cases of the virus have been reported in Canada, but that has not stopped health professionals from calling attention.
“We've seen a lot of people who have had a lot of trouble with the disease,” said Isaac Bovan Gogh, an infectious disease expert at Toronto General Hospital.
What are the symptoms of the West Nile virus?
According to Infection Prevention and Control Canada (IPAC), the West Nile virus first arrived in Canada in August 2002.
IPAC says the virus mainly infects birds and then spreads to humans by mosquitoes that feed the blood of those birds.
So far this year, no human cases have been reported in Canada, but Bogoch said it is usually seen in the summer and late to early summer fall.
When it comes to viruses, about 70-80% of people are infected, so you may not realize you have them because they do not have symptoms.
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However, those who do so usually experience symptoms such as fever, headaches, body pain, mild rashes, and swollen lymph glands.
Symptoms usually appear within 2 to 15 days after infection.
Canada's public health agency says less than 1% of people infected with the virus develop severe symptoms and health effects.
According to PHAC, people over the age of 50, those with chronic diseases such as cancer or heart disease, and those with weakened immune systems are at increased risk for severe symptoms.
In severe cases, people can face a rapid onset of severe headaches, high fever, a stiff neck, nausea and vomiting, difficulty swallowing, drowsiness or confusion.
PHAC says that loss of consciousness, lack of coordination, muscle weakness, or paralysis is also possible in severe cases.
“It rarely causes neurological symptoms and it can become more serious,” Bovan Gogh said.
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“It can cause inflammation of the brain, inflammation of the areas around the brain and spinal cord, meningitis-type images, and then rarely lead to paralytic syndromes that are truly reminiscent of polio.”
Canadian family doctors, the official publication of Canadian universities, notes that between 3 and 15% of people with severe illnesses can die.
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“It's very rare, but laughter doesn't matter again,” Bovan Gogh said.
Mild cases usually take a week to recover, but PHAC says they can see various health effects that some serious cases can last from months to years of illness.
People who develop West Nile symptoms after being bitten by mosquitoes are prompted to meet their healthcare provider immediately.
The risk of contracting West Nile virus begins in mid-April and usually lasts until the first hard frost in late September or October.
The highest risk for humans is between mid-July and early September, with mosquitoes often being most active at dawn and dusk.
PHAC says when outside, people should wear long pants and wear loose, long-sleeved shirts, socks and hats to cover exposed skin. PHAC points out that mosquitoes are attracted to dark colors, so people need to wear brightly colored clothing.
People are also encouraged to use insect repellents that contain DEET or Icaridin. This also helps prevent bites.
The health agency says Canadians can take steps to reduce mosquitoes near their homes. This means by removing water around your home and placing screens on windows and doors.
But West Nile is a concern, Bogoc says that whether Canadians enjoy summer camping or not, whether they enjoy Canadians on the beach, at cottages or summer camping, should not prevent them from enjoying the summer.
“We should go outside and enjoy it as much as possible as we can, as we are around the corner in the winter,” he said. “But there's no reason to hide the indoors for this. Just go outside and have a great time and be aware that they're there.”
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