Dramatic rise in bloodsucking ticks predicted for Eastern Canada
Dennis Bueckert
Canadian Press
Tuesday, September 20, 2005
OTTAWA (CP) - Bloodsucking ticks that cause Lyme disease can be expected to flourish in much of Eastern Canada as climate change brings milder winters, researchers say.
Lyme disease - a non-fatal condition that can be debilitating and lifelong - is rare in Canada but ranks among the top 10 infectious diseases in the United States, which has about 20,000 cases each year. Scientists have already identified six Canadian infestations of ixodes scapularis, commonly known as the blacklegged deer tick, considered efficient at spreading Lyme disease, a conference heard Monday.
Until the early 1990s, there was only one such population in Canada, University of Montreal microbiologist Nick Ogden told the annual meeting of the Canadian Public Health Association.
By 2020, much of southern Ontario and Quebec will be suitable habitat for the dreaded tick, said Ogden.
"Our conclusion so far is that a northward expansion of the range of the tick is likely. Tick survival is going to increase dramatically."
He said the tick may be prevented from spreading through the Prairies by lack of humidity.
There is a west coast version of the tick, ixodes pacificus, but it is not nearly as efficient at spreading Lyme disease.
Ogden said ticks are already being carried northward by birds, and they have been identified in populated areas across Eastern Canada. He suggested doctors should be on the lookout for the disease.
Lyme disease is difficult to diagnose and there are suspicions that many Canadian cases go undetected because the symptoms resemble chronic fatigue syndrome. Common symptoms include headache, fever, fatigue and a characteristic skin rash.
A separate study presented at the conference predicted climate change will bring a rise in waterborne disease as extreme rainfall events overwhelm drainage and water purification systems.
A study by Daniel Gillis of the University of Guelph concluded that an outbreak of waterborne disease is four times more likely to occur following an extreme rainfall.
That's because heavy rainfall is likely to cause overland water flow, resulting in contamination by manure and other organic matter - as happened in the Walkerton tainted-water tragedy.
Hazel Lynn, medical officer of health for Ontario's Grey-Bruce County, which includes Walkerton, said much of rural Canada in vulnerable to the same type of incident.
Water purification systems which depend on chlorine without filtration are ineffective for treating water with a lot of organic matter, she said. Shallow wells in rural Canada are vulnerable because they don't have filters.
"There is a significant association between extreme rainfall and waterborne disease," said Kate Thomas of the Public Health Agency of Canada, who presented Gillis' paper.
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