As this year's relatively mild season for West Nile virus winds down in Canada, some public health experts are urging people not to become complacent about protecting themselves in the future.

Experts say the North American experience with the virus has varied from the usual outcomes for mosquito-borne diseases.

In 2006, there were 110 human cases across the country. British Columbia shows no signs of the virus, yet would seem to be particularly vulnerable, because the right mosquitoes, birds and warm climate exist there to host the virus, said Dr. Bonnie Henry of the B.C. Centre for Disease Control.
 
"We have no reason to believe that it's not going to come," said Henry. "It's just a matter of time."

West Nile virus is unpredictable. Until it hit the U.S. and Canada, no one knew the virus could be transmitted through blood, breastfeeding or organ transplants. A small percentage of infected patients show severe, polio-like symptoms, which was also unexpected.

People in North America may be experiencing the virus differently because the strain here may be more virulent than the predominant strain in Africa.

With little West Nile virus activity since 2004, public awareness has faded. Many don't follow the advice to wear long-sleeved clothing after dusk, or to rid their property of standing water.

Potential for West Nile outbreak exists

But mosquitoes in most provinces carry West Nile virus, and with the right weather conditions, such as a hot July, some areas could see a large spike in human cases next year.

"Perhaps we will get some conditions that will give us an unusually large number of mosquitoes, perhaps a longer mosquito season," said Harvey Artsob of the Public Health Agency of Canada in Winnipeg.

Infectious disease specialist Dr. John Embil of the Manitoba Health Sciences Centre has treated some patients who were gravely ill with West Nile, and others whose symptoms were so mild they didn't know they had it.

Embil said he's glad the initial panic around West Nile has faded, and he doesn't expect large numbers of human cases in the future.

"We can take this to its most illogical conclusion and say, 'Oh my God, we've got a West Nile fiasco,' but we don't," said Embil. "We may have had a heightened level of West Nile activity two years ago, but we saw a gradual decline with time."

Experts disagree about the future of West Nile virus. Some say as more of the population becomes infected, people will build up immunity; others say that with the right weather conditions many Canadians could be vulnerable.

For Maurice Dunn of Winnipeg, one mosquito bite turned his life upside down. He was diagnosed with West Nile last month and is now out of hospital, but still showing neurological side-effects.

"I have a headache most days," said Dunn. "If I get up, I'm very, very dizzy, very light-headed. My whole body trembles."

Dunn said he doesn't blame anyone for his condition, but wishes he'd taken the threat more seriously, and hopes other Canadians will as well.