TUESDAY, June 12, 2001 (HealthDayNews) -- Antibiotics may help prevent Lyme disease, but they won't clear up stubborn symptoms that sometimes persist long after the disease has been treated, new research says.
When given within three days of a tick bite, the generic antibiotic doxycycline can ward off Lyme disease. Yet the drug proved less effective, and possibly even worse, than sugar pills in treating lingering symptoms, a new study finds. The symptoms were thought to be the result of chronic infection with Lyme-causing bacteria, but the researchers say the new finding suggests that chronic Lyme disease may at best be a misnomer and at the very least may be a syndrome unconnected to those germs.
The findings are reported in the July 11 issue of the New England Journal of Medicine, which released them ahead of schedule because of their potential importance to patients.
Lyme disease is an infection caused by Borrelia burgdorferi, a bacterium that hitches a ride in deer ticks and western black-legged ticks. The condition, whose symptoms include a signature bulls-eye rash and joint swelling, affects about 16,000 Americans a year, almost exclusively in the Northeast and Wisconsin, where deer ticks are prevalent.
The vast majority of patients with Lyme disease respond well to antibiotics. However, perhaps 5 percent or so suffer a chronic syndrome of diffuse aches, pains, memory trouble and various other problems that wax and wane for months, even years. The complications often improve with antibiotic therapy, only to flare up when the drugs are stopped, leading some doctors and patients to conclude that the syndrome is a manifestation of hidden reservoirs of bacteria that can't be eradicated.
But the latest research indicates that, whatever the cause of chronic Lyme disease, it's not untreated infection.
A research team led by Dr. Mark Klempner of the New England Medical Center in Boston compared antibiotic therapy to placebo treatment in more than 100 people with stubborn Lyme disease symptoms but no chemical or genetic traces of the bacteria in their bodies.
Some patients received a one-month course of intravenous antibiotics followed by two months of treatment with doxycycline pills. The rest received dummy injections first and then dummy pills.
The study was stopped early when researchers realized that the drug regimen wasn't helping. While 37 percent of patients on the antibiotics said they felt better physically and mentally, 29 percent saw no change and 34 percent said they'd grown worse.
Of those on placebos, 34 percent reported feeling worse, 26 percent said they felt no change, and 40 percent said they were doing better.
"Most patients [receiving real treatment] either stayed the same or got worse, which argues strongly against an infection causing this," says Dr. Arthur Weinstein, a joint specialist at the Washington Hospital Center in Washington, D.C., who helped conduct the study while at New York Medical College in Valhalla. "We don't believe that these symptoms are related to ongoing, acting infection," he says.
On the other hand, Weinstein says the researchers do not believe people who think they have chronic Lyme are faking their ailments. "This is a serious problem with an unknown cause," Weinstein says. "We hope that this paper doesn't diminish the way academic physicians and physicians in general will view this condition."
Weinstein says patients who don't shed Lyme symptoms may have autoimmune disorders or a genetic predisposition that allows them to persist. Knowing that infection isn't the answer will enable researchers to focus more on other potential causes, he says.
In a second study, a team led by Dr. Robert Nadelman of New York Medical College compared a preventive course of doxycycline -- 200 milligrams within 72 hours of a deer tick bite -- with placebo therapy to prevent Lyme disease in 482 New York residents.
The drug did appear to help stave off the disease in nearly 90 percent of the patients who took it; however, measures of its success varied from as low as 25 percent to 98 percent, the researchers say.
What's more, the antibiotic caused significant side effects, including nausea and vomiting, in 30 percent of patients, roughly three times the rate of reactions in those who took placebos.
The risk of Lyme disease is directly linked to the maturity and feeding state of the offending parasite, the researchers say. None of nearly 100 untreated subjects bitten by adult ticks got the disease, nor did any of the three dozen bitten by younger nymphal ticks that had not had enough time to start swelling with blood.
However, Lyme disease did occur in eight untreated patients on whom partially engorged nymphs were found. "If somebody can reliably identify a nymphal tick and determine engorgement, then that would be a person in whom prophylactic treatment [with doxycycline] could be considered," Nadelman says.
Therein lies the rub, experts say. The state of satiety of a deer tick is not only hard to determine, but many people have trouble distinguishing between the parasites and harmless blemishes like moles or scabs.
"For the vast majority of people the risk is going to be so low that the side effects of treatment" outweigh its benefit, says Dr. Eugene Shapiro, a Yale University Lyme expert and author of an editorial accompanying the journal articles.
Shapiro says the worst that can happen if preventive measures aren't taken is that a person develops Lyme disease, to which "virtually no one doesn't respond well to treatment."
What To Do
A vaccine, LYMErix, made by GlaxoSmithKline, is available and can prevent nearly 80 percent of full-blown cases in those who receive the three-dose shots.
To learn more about Lyme disease, visit the Centers for Disease Control and Prevention or the American Lyme Disease Foundation.
Read other HealthDay articles about Lyme disease.
