Diagnosing early Lyme disease.

The diagnostic value of clinical, culture, and serologic findings was studied prospectively in 41 patients with early Lyme disease. Fifteen patients had erythema chronicum migrans alone, and 26 had clinical evidence of disseminated infection, most commonly affecting the brain or meninges, other skin sites, lymph nodes, or joints. Of 40 blood cultures, only one, from a patient with disseminated infection, yielded spirochetes. One of 10 patients tested with localized infection had an elevated IgM response to the Lyme spirochete (200 units or greater) during acute disease. Two to three weeks after beginning antibiotic therapy, four of the 10 patients had elevated specific IgM or IgG responses (200 units or greater). Of the 22 patients tested with disseminated disease, 10 initially had elevated levels of specific IgM or IgG, and 12 had such responses by convalescence. Because of the low yield of cultures and the delay in the specific antibody response, recognition of the clinical picture remains very important in diagnosing early Lyme disease.