Picking out the Lymes from the lemons.

Ever since Lyme disease became well known back in the '70s, Lyme-transmitting ticks have aroused a public worry much like that caused by frothy-mouthed dogs. And with 1,282 cases of Lyme disease reported across the United States so far this year, no one denies that the disease poses a real health threat. But some researchers are beginning to wonder whether Lyme may produce a previously undocumented symptom: paranoia.

Researchers at the University of Connecticut Health Center in Farmington and the Yale-New Haven Hospital examined 70 children diagnosed with Lyme disease and found that only 53 percent of them actually harbored the Lyme-causing bacterium, Borrelia burgdorferi. The remaining 47 percent, they discovered, had been misdiagnosed. To confirm these findings, the researchers telephoned parents of teh misdiagnosed children one to three years later and found that advanced symptoms of the disease never materialized.

"The problem of Lyme disease is real, but I think a lot of people have become hysterical about it, including some doctor," says study coauthor Henry M. Feder Jr., a pediatrician at the University of Connecticut Health Center. Feder reported his group's findings at the American Pediatric Society meeting in Baltimore last week.

In its early stages, Lyme disease produces symptoms -- such as fever and muscular aches -- similar to those of many other illnesses. This makes diagnosis difficult. "If a doctor sees a patient and wants to make the symptoms fit Lyme disease, he can do it. That's the tricky part of it," Feder says.

Furthermore, blood tests widely used to screen for Lyme disease often yield ambiguous results. These tests look for antibodies in the bloodstream. But since the body mounts a very weak immune response to B. burgdorferi, the antibodies sometimes elude detection, making diagnosis a judgment call. Moreover, commercially available test kits vary widely in their reliability. Feder's group carefully prepared their own blood test rather than use a commercial kit.

Faced with inconclusive evidence, physicians often prescribe antibiotics just in case. But this approach has risks too. For example, freely distributed antibiotics could allow other infectious organisms to build up a tolerance, notes Andrew Spielman of the Harvard School of Public Health in Boston.

In recent years, scientists have developed more accurate tests that look for B. burgdorferi DNA rather than for human antibodies (SN: 12/9/89, p.374), but these genetic tests haven't become widely available. Until they do, diagnosing Lyme disease will continue to involve an element of guesswork. At the same time, Feder advises clinicians to weigh the evidence and the odds more carefully: "If someone gets a tick bite in a Lyme-endemic area, the risk is one in 100 of getting [the disease]. So saying, 'Uh-oh, a tick bite, you're in big trouble' -- that, in my mind, is just not right."