For the first time, doctors have shown that a quick dose of the antibiotic doxycycline can ward off Lyme disease after a tick bite.
Results of a second study published by the same journal suggest that long term antibiotic treatment may not help people who are seriously debilitated by symptoms of Lyme disease after initial treatment.
Because of the importance of these findings, the New England Journal of Medicine published the reports on its website ahead of their scheduled publication in the 12 July issue.
Some physicians already give antibiotics to people who are bitten by deer ticks, which spread Lyme disease. Until now, however, many experts opposed this because there has been no clear evidence that the treatment prevents the disease, even though antibiotics can clear up Lyme disease once it occurs.
In the first study Dr Robert Nadelman of New York Medical College in Valhalla and colleagues gave 235 patients a 200 mg dose of doxycycline and another group of 247 patients a placebo pill. All the study participants were living in Westchester County, a region north of New York city with one of the highest rates of Lyme disease in the United States.
All the participants had removed at least one deer tick from their body during the 72 hours before receiving the treatment, and experts had determined that the tick was a variety that carried Lyme disease.
Overall, one person (0.4%) in the group that received treatment with doxycycline developed the spreading “bull's eye rash” characteristic of the illness, compared with eight people (3.2%) in the group that were given placebo.
Generally, about 80% of patients with Lyme disease experience the spreading rash as the first symptom of Lyme disease. “The efficacy of treatment was 87%,” the researchers concluded.
However, the study's follow up period lasted for only six weeks, and the patients could go on to develop arthritis or neurological symptoms, although the researchers believe it is “unlikely.”
In a second study, Dr Mark Klempner of Boston University School of Medicine found that prolonged antibiotic treatment is ineffective against this condition. The patients in this study all had well documented Lyme disease and had been treated for the illness, but they still experienced persistent muscle and skeletal pain, cognitive impairment, or other symptoms, often accompanied by fatigue.
In their study, Dr Klempner's team gave the patients intravenous ceftriaxone or a placebo for 30 days, followed by oral doxycycline or a placebo for 60 days. The study was halted, however, after the participants given the antibiotics were found to fare no better than those given the placebo.
The three articles can be found on the New England Journal of Medicine's website (http://content.nejm.org)
Figure.
DAVID SCHARF/SPL
Deer tick: responsible for spreading Lyme disease