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What is Lyme disease and how is it is contracted?
Lyme disease is an infection transmitted through the bite of an infected deer tick. Lyme disease occurs when a tick infected with a spirochete form of bacterium, known as Borrelia burgdorferi, enters the blood stream and begins to invade other body tissues. Along with deer, the tick also can be found on some other small animals like rodents.
People get Lyme disease most often in the late spring and early summer months when outdoor activities start to peak. In the fall, hikers and hunters are at higher risk for Lyme disease.
In spring, the tick is in the nymph stage, which is much smaller than an adult tick. It's very easy to get bitten and infected by the nymph without ever knowing it. In general, the tick needs to be attached to someone for at least 36 hours to transmit the infection.
The bacteria that cause Lyme disease are named after the discoverer, Dr. Willy Burgdorfer. The first case of Lyme disease in the United States was diagnosed in 1975 when a cluster of children in Lyme, Conn., developed a peculiar form of arthritis. More than 157,000 cases have been reported to health authorities in the U.S. since 1982, when a systematic national surveillance began.
Where is Lyme disease most prevalent?
In 2004, 19,800 cases of Lyme disease were reported to the CDC. Almost all of these cases were from Connecticut, Delaware, Rhode Island, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New Hampshire, New York, Pennsylvania and Wisconsin. Children ages 5 to 14 and adults 40 and older have the highest incidence rates.
Lyme disease is more common in the northeast regions of the U.S. for two reasons. There are large numbers of the deer ticks' preferred hosts - including deer and white-footed mice - and they live close to humans. At greatest risk are people in endemic areas who visit grassy, wooded locations near streams or lakes that are inhabited by white-tailed deer and mice. These areas are in the Northeast and upper Midwest states and along the Northern Pacific coast of California.
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External Source
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The Centers for Disease Control and Prevention
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This article was reviewed and updated June 2007.
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