Single-dose prophylaxis against Lyme disease

摘要

We are puzzled by David Volkman's assertions and conclusions in his letter. Many of his statements are factually incorrect or misinterpretations of the literature. In the study of antimicrobial prophylaxis for tick bites published in 2001 in the New England Journal of Medicine, which involved nearly 500 evaluable participants, it was shown that a single 200 mg dose of doxycycline was 87% effective (95% CI 25-98). As clearly stated in this report, the primary outcome measure was the development of erythema migrans at the site of the bite-not testing for the presence of antibody to Borrelia burgdorferi. Development of this characteristic skin lesion at the bite site is the only reliable marker of infection caused by a specific tick bite. Volkman seems to be unaware that blood cultures were done for each patient at three different times (albeit that low volume blood culture for B burgdorferi is relatively insensitive). Moreover, the findings reported in this study contradict his assertion that people withone tick bite would be unlikely to sustain another during the same season; 18% of the patients reported a second tick bite within just 6 weeks of the initial bite.