A Controlled Trial of Antimicrobial Prophylaxis for Lyme Disease after Deer-Tick Bites

LYME disease, caused by Borrelia burgdorferi , is transmitted by the deer tick, Ixodes dammini , in the northeastern United States. 1 In areas in which the disease is endemic, deer-tick bites are common and can cause tremendous anxiety, but there is uncertainty about how the care of persons who are bitten should be managed. We conducted a double-blind, placebo-controlled, randomized clinical trial to assess the risk of infection with B. burgdorferi after a deer-tick bite and to determine whether antimicrobial prophylaxis is effective in reducing this risk. Methods Enrollment and Randomization of the Subjects From May 1989 through November 1991, . . .