Summer afternoon. “The two most beautiful words in the English language,” mused author Henry James.

But when dusk falls in Canada, things can turn ugly. In just minutes, chattering patio guests resort to a slap-fest and the hardiest of gardeners retreat indoors.

Mosquitoes! A mere irritant for most, but each summer an unlucky few will fall victim to these suckers. Last year, 36 human cases of West Nile virus emerged in Canada—a substantial drop from 2007, when the country had a record 2,215 hits.

The virus is passed from infected birds to humans via mosquitoes, and is not transmitted between humans as the H1N1 virus is.

“Some very general figures are that, for every 100 people bitten by an infected mosquito, only 20 will develop symptoms, mainly fever,” says Dr. Harvey Artsob, zoonotic diseases and special pathogens director at Health Canada’s National Microbiology Laboratory in Winnipeg. “Perhaps one in 100 will develop neurologic symptoms, such as meningoencephalitis, but, in fact, fatalities are rare.”

Gardeners are on the first line of defence in the fight against West Nile virus, and are well placed to break the mosquito’s breeding cycle.

It takes four days for the eggs — laid in stagnant water — to hatch. So twice a week be sure to drain pool covers, flowerpot saucers, wheelbarrows, garbage cans, old tires and birdbaths.

Cover rain barrels with screens, and clean eavestroughs and drains regularly. Stock up with fish in the pond — they love to snack on mosquito larvae — or use a pond aerator. Ensure pool and hot tub water receive the proper amount of chlorine. And, as mosquitoes look for shelter in the heat of the day, keep lawns trimmed and unruly shrubbery pruned.

There is no vaccination or treatment for West Nile virus and, although the elderly and immunosuppressed may be at higher risk, serious disease has been documented in all age groups. “We therefore want all individuals to take precautions to reduce their exposure to mosquito bites,” says Artsob. “Particularly during the high-risk season, which is late July until the first hard frost.” For further information, visit Canada’s Public Health Agency website: