My friend Anne and her husband, Richard, spend summers at a resort in Westchester County, New York, that has a swimming lake, tennis courts, gardens and beautiful grounds surrounded by woods. But Anne never sets foot on the grass.
The reason is Lyme disease. Anne says just about everyone she knows who partakes of the greenery and gardens outside the cabins has contracted the disease. So not only is she cautious about venturing out, but she and her husband also check each other daily from head to toe for the much-feared deer tick, which can transmit the disease when it attaches to skin and feeds on blood.
This tick, which is the size of a pinhead when it starts searching for a bloody meal, is responsible for about 20,000 reported cases of Lyme disease each year in the US (the actual number is believed to be 10 times that) and 60,000 reported cases in Europe. Cases have been reported in every state, with residents of the Northeast, the Great Lakes region, northwestern Washington state and parts of California the most frequent victims.
In some areas, as many as half of the deer ticks are infected with Borrelia, the Lyme disease bacterium. The disease got its name in 1975 from the first identified cluster of cases, among children in Lyme, Connecticut, who had rheumatoid-like symptoms of swollen, painful joints.
The white-tailed deer and white-footed mouse are the tick’s most frequent hosts, but it also feeds on birds, dogs and other rodents, including squirrels. The tiny nymphal form that emerges in spring and early summer presents the greatest hazard to humans. It is also the hardest to spot, especially on body parts covered with hair.
People usually acquire the tick while walking through grassy or wooded areas. Sometimes pet dogs are the source: In Minnesota one summer, our dog got more than 30 deer ticks on his face, apparently from sticking his nose into a fresh carcass. Unlike the common dog tick, which is round and very dark, the deer tick is elongated and brownish.
The disease can be maddeningly difficult to diagnose. Only 50 percent to 70 percent of patients recall being bitten by a tick. Ordinary laboratory tests are rarely helpful. Tests for antibodies to the bacterium or for its genetic footprints result in many false-negative and false-positive findings.
Rather, according to Robert L. Bratton and colleagues at the Mayo Clinic in Scottsdale, Arizona, who reviewed the recent literature on Lyme disease in the May issue of Mayo Clinic Proceedings, most cases are best diagnosed and treated based on patients’ symptoms. Thus, doctors everywhere must be alert when dealing with patients who live or travel in areas where Lyme disease is prevalent, and they must be willing to use appropriate antibiotics based on a clinical assessment rather than laboratory findings.
EARLY SYMPTOMS
Since signs and symptoms vary and often do not appear until one to four weeks — or even months — after exposure, anyone bitten by a deer tick may be wise to obtain preventive treatment with an antibiotic, according to Lyme disease experts consulted by Constance A. Bean, the author with Lesley Ann Fein of the new book Beating Lyme.
The most common sign is a reddish rash called erythema migrans that often resembles a spreading bull’s-eye, though up to 20 percent of patients never develop it. Common sites of the rash are the thigh, groin, buttock and underarm. It may be accompanied by flu-like symptoms: fever, chills, body aches, headache and fatigue.
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