Thursday, July 10, 2008

Lyme disease risk swells as ticks fan out in Canada

Globe and Mail (Toronto): The small, blacklegged ticks that cause Lyme disease are popping up in new regions across the country, prompting the Public Health Agency of Canada to develop new maps to educate the public about the spreading risk.

The tick population in Canada used to be confined to one region of Ontario, on the Long Point peninsula in Lake Erie. But in the past 10 years, the bugs have spread across the country, carried by the birds on which they feed, and Public Health says doctors should no longer rule out infection because of geographic location. "

What we've seen is definitely an expansion," said Robbin Lindsay, a research scientist with the agency. "Tick populations are expanding into new areas and in different provinces where we haven't seen them before."

The agency has now confirmed populations in B.C.'s Lower Mainland, on Vancouver Island, in the southeastern corner of Manitoba, along the shores of Lake Erie and Lake Ontario and within Nova Scotia, where the critters appear to be moving inland from the coast. "We're investigating a third location in Nova Scotia this month," he said. "There's a good chance there'll be a new dot on the map."

There have also been human cases of Lyme disease corresponding with the spread of the bugs across the country, and Dr. Lindsay expects the numbers to grow as the ticks establish new habitats. Lyme disease can have devastating effects for those it infects. It can often be hard to diagnose, which can result in months of suffering and confusion…..

….The official number of reported cases of Lyme disease in Canada remains relatively low, with approximately 300 cases since 2004, according to Health Canada. But a growing number of Canadians are sending blood tests south of the border for diagnosis. In the United States there are more than 20,000 cases each year, and some believe the disparity in diagnoses may be because many Canadian physicians still believe ticks are not endemic in Canada….

A male Ixodes ricinus tick (smaller) copulating with a female tick (larger). This shudder-worthy pest is a vector for the spirochete that causes Lyme disease. Image from the Centers for Disease Control, Wikimedia Commons

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