how to protect yourself from mosquitoes and west nile virus
humans are at greatest risk of contracting west nile virus when mosquitoes are most active: at dawn and dusk, from mid-april to the first “hard frost” in september or october.
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most people who are diagnosed with west nile virus will not experience long-term side-effects, according to toronto public health. getty
getty
no one likes dealing with a mosquito. the constant buzzing and itchy bites are enough to drive even the hardiest of outdoorsy types indoors. and now, with environmental groups warning that global warming will increase the abundance of mosquitoes and the diseases they carry — like west nile virus — canadians have more incentive than ever to protect themselves against mosquitoes.
since the first human case of west nile virus (wnv) was identified in canada in 2002, local public health regions monitor for cases in humans, mosquitoes, birds, and other animals. cases in humans have fluctuated rather dramatically in canada, with a record 2401 cases reported in 2007, while preliminary case counts for 2022 showed 47 cases in canada and 1,126 cases in the united states. there were also 90 deaths associated with west nile in the united states in 2022.
how is west nile virus spread?
west nile virus is usually spread by mosquitoes, who pick up the virus when feeding on contaminated birds. because of this, humans are at greatest risk of contracting west nile virus when mosquitoes are most active: at dawn and dusk, from mid-april to the first “hard frost” in september or october.
wnv can’t be transmitted under “normal circumstances,” toronto public health explained to healthing over email, which includes touching or kissing someone who has the virus. it can, however, be transmitted from a mother to a child during pregnancy, delivery or breast feeding. it is also possible to contract wnv from a blood transfusion or an organ transplant so, in canada, blood and organ donations are screened to minimize this risk.
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what are the symptoms of west nile virus?
thankfully, most people who are diagnosed with wnv will not experience long-term side-effects, according to toronto public health. in fact, 70-80 per cent of people infected will not experience any symptoms of the virus. most patients who do have symptoms will only experience the mild variety, which can include headache, body aches, fever, rash and/or swollen lymph glands.
in less than one per cent of patients, the virus will affect the central nervous system (brain and spinal cord), causing severe health effects and long-term neurologic problems. these can include a stiff neck, difficulty swallowing, confusion, lack of coordination, muscle weakness, paralysis, and loss of consciousness. individuals at highest risk for developing severe symptoms include people who have weakened immune symptoms, for example, over 50 years of age; who have chronic diseases such as heart disease, alcoholism, and diabetes; or are undergoing chemotherapy.
there is no specific treatment for wnv, toronto public health explains. the goal of treatment is to help lessen symptoms and, in severe cases, provide breathing assistance and iv fluids. most patients who have symptoms will fully recover within a few weeks to months.
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how do you protect yourself from mosquitoes?
anecdotally, biologists have been reporting an increase in the mosquito population in regions across canada. this is likely due to a combination of many factors, including more hardy mosquito species being transported to canada through trade, mild winters which allow more mosquito eggs to survive to the spring (mosquitoes lay their eggs in fall, which then hatch in the spring), and the pesticide ddt finally dissipating from our water decades after it was banned.
although the risk of contracting west nile virus is low in canada, canadians are still encouraged to take precautions against getting bit by mosquitoes. the first measure of defence is creating a barrier between you and the bugs, including wearing long pants and sleeves (preferably in a lighter colour) and ensuring doors and windows left open have a tight-fitting screen.
health canada also reaffirms deet is safe to use, so long as it is applied properly and in the correct concentrations. also known as n, n-diethyl-m-toluamide, deet works by interfering with the antennae on biting insects, blocking them from being able to detect key chemicals emitted by humans and other animals that signal a food sources. adults and children over 12 years old can use up to 30 per cent concentration of deet, while children aged 2-12 years old can use repellents with 10 per cent deet up to three times daily. babies from six months to two years old can also use 10 per cent deet once per day, but infants under 6 months of age should not be exposed to deet, and instead should be protected by nets over their strollers/playpens, and by wearing clothing with long sleeves and pants.
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other options for mosquito repellent, according to health canada, include products containing soybean oil or a mixture of geranium, lemon, pine needle, eucalyptus and camphor — although essential oils are not safe to use on children under two years of age. clip-on devices containing metofluthrin may also work and are safe for kids as long as they do not handle the refill discs.
beware of mosquito breeding grounds and other potential sources of west nile virus
it’s common knowledge that, generally, mosquitoes lay their eggs in standing water. what can be surprising, however, is how little water mosquitoes need for their breeding grounds. aaron soudant, director of quality assurance at abell pest control, says he’s found rafts of eggs in eavestroughs and even knot holes in tree trunks. flat roofs may also hold water, so it’s a good idea to check them regularly (not to mention that pooling water would be awful for the roof itself.)
because mosquitoes are believed to pick up the virus from infected birds, it is also important to handle dead birds with extreme caution. if you do need to dispose of a dead bird on your property, health canada recommends wearing gloves then, once you are done, washing your gloved hands and then washing your bare hands.
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emma jones is a multimedia editor with healthing. you can reach her at emjones@postmedia.com or on instagram and twitter @jonesyjourn.
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