The Lowdown on Lyme Disease

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Ticks carry the bacteria in their midgut, so an extended period of feeding—usually 36 to 48 hours—is necessary for them to transmit the disease. Therefore, checking for ticks regularly when spending time outdoors is your first line of defense. But because of their tiny size, it is entirely possible to carry a nymph on your body, have it feed and then drop off without ever knowing you were bitten.

"People don't realize how small the ticks are," says David Duffy, a professor of botany at the University of Hawaii who led a study on the effectiveness of guinea fowl in reducing tick populations in New York. "Be a little paranoid," he advises.

In the Northeast, about 25 percent of black-legged nymphs and 50 percent of adults carry the Lyme disease bacteria, says David Weld, executive director of the American Lyme Disease Foundation (ALDF). In Georgia and regions farther south, tick infection rates drop to 4 percent and 8 percent, respectively. In the upper Midwest, 25 percent to 50 percent of blacklegged ticks are infected; on the West Coast, infection rates usually average from 5 percent to 15 percent for nymphal ticks and about 1 percent to 4 percent for adult ticks. The main reason for the disparity across the regions is that more species of lizards and small mammals that are ineffective hosts for the bacteria live in the warmer areas. "Lizards have a protein that kills the bacteria," Weld says.

SYMPTOMS VARY

The symptoms of Lyme disease are not exactly the same in every person who becomes infected. In many cases, a red rash appears in either a ring-like pattern or as a red spot around or near the bite anywhere from several days to several weeks after the person contracts the disease from an infected tick. The rash seldom causes pain or itching, and usually persists for three to five weeks. On dark-skinned people, the rash may appear as a dark, bruise-like ring and often is hard to notice.

Other early signs of infection resemble the flu and can include chills, fever, joint pain and fatigue accompanied by swollen lymph nodes nearest the bite. This may seem like the flu, and symptoms may go into remission, but if it is Lyme disease, it most likely won't go away without treatment. Several antibiotics are highly effective, but if the disease is not treated promptly, the bacteria will move into other parts of the body, including the muscles, nerves, joints and brain. Late-stage Lyme disease is debilitating, causing severe arthritis, mental confusion, numbness of the arms and legs, and heart problems such as arrhythmia. It is sometimes difficult to treat.

In late 1998, a human vaccine for Lyme disease became available, but some patients who received the vaccine developed severe arthritis and sued the manufacturer, GlaxoSmithKline, who later discontinued the product, citing poor sales; the class-action case was settled in July 2003. No vaccine for the disease is available at this time.

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