Lyme Disease’s Unusual Suspects

By Martin Enserink
ScienceNOW Daily News

A new study challenges the widely held view that mice are the main animal reservoir for Lyme disease in the United States. The paper, published online this week in the Proceedings of the Royal Society B, shows that two shrew species are just as important and that chipmunks play a supporting role. Unless those species are taken into account, say researchers, efforts to control Lyme disease are doomed to fail.

Lyme disease can cause anything from rash to arthritic and psychiatric diseases. Borrelia burgdorferi sensu stricto, the bacterium that causes Lyme disease in the United States, is transmitted to humans by blacklegged ticks. Researchers have assumed that the vast majority of ticks become infected when, as larvae, they take their first blood meal from a white-footed mouse. Indeed, lab studies have shown that as many as 90% of ticks feeding on an infected mouse pick up the bug, an “extremely high number,” says disease ecologist Dustin Brisson of the University of Pennsylvania.

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