BC begins its WNV countdown

The Rocky Mountains have provided some protection so far, but as summer approaches British Columbia is bracing for the arrival of West Nile virus (WNV).

Dr. Murray Fyfe, an epidemiologist with the BC Centre for Disease Control (BCCDC), says that mapping of the virus in North America indicates that mountain ranges offer some protection, but once that barrier is breached he expects the virus to spread unimpeded along Canada's West Coast. WNV was found in dead birds in neighbouring Washington State late last summer.

BC has already designated WNV infection a reportable disease, and a multiagency provincial plan emphasizes tailor-made responses for different regions. Sparsely populated areas may be employing only public education campaigns, says Fyfe, while mosquito-control measures, such as placing larvicide pellets in breeding locations or eliminating these sites, will be used in heavily populated areas when practical. Water in natural reservoirs such as lakes cannot be treated without provincial authorization. Spraying insecticides is considered a last resort, but the use of larvicides in pellet and other forms could begin this month. Public education to prevent mosquito bites and breeding in people's yards has already begun. “I'm hoping the integrated approach is the way to go,” says Fyfe.

Dozens of mosquito traps were set up around the province in May, and the samples will be sorted by species and tested at the BCCDC.

Fyfe says it is impossible to predict WNV's impact. “They say this will take many months, if not years. We don't fully understand the ecology of the virus in North America, and it behaves differently in different places. We are going to do what we can this year, and based on what we find, we will revise our plan for the coming years.”

He says WNV poses a difficult public health challenge. “On the one hand we don't want to minimize this, [but on the other hand] you want to put it into perspective so that people don't think they shouldn't go camping anymore because they may come across a mosquito. But that balance will be difficult to reach.” — Heather Kent, Vancouver