Researchers from Brock University say recent numbers point to one of the worst West Nile Virus (WNV) outbreaks in Ontario over a 15 year period.
The group, led by Professor Fiona Hunter, a medical and veterinarian entomologist, crunched data from Public Health Ontario’s West Nile surveillance program and says this year’s numbers fall between epidemic numbers recorded in 2002 and 2012.
“In 2002 it was about 400 (human) cases, and 2012 about 250 cases, we’re in that ballpark again.”
The report examined climate data from seven municipalities which identified a strong relationship between the confirmed number of human cases and positive “Culex” mosquito pools in each of the years between 2002 and 2017.
Hunter says it took almost a whole year of looking at extensive data sets to produce a model which could predict the number of potential WNV cases in humans.
“We were looking at weather patterns, precipitation, and temperatures and finally came up with a model that showed that the number of positive mosquito pools during the season will directly translate into the number of human cases by the end of the season.”
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Hunter says the Genus: Culex species are known for being bird biters, which is how they pickup WNV and transmit the infection.
However, as the insect gets closer to the end of its short life, anywhere from 42 – 56 days, they become a little more desperate to find a victim.
“We find that these mosquitoes start loosening up their preferences for who they are going to feed on. So if they can’t feed on a bird right away, they’ll just feed on whatever warm-blooded animal is nearby.”
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Avoidance is the only way to deal with WNV as there are no vaccines or medications available for treatment. The worst cases in humans could lead to encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord) according to the Centers for Disease Control.
Hunter says one other way for Ontarians to avoid contracting the disease, is if the province gets hit by a cold snap in the fall.
“I’m hoping we get a cold snap in September to knock down the population.”
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