A serological survey and review of clinical Lyme borreliosis in Spain.

A serosurvey for Lyme disease was conducted by the National Reference Center for Microbiology in Spain. All serum specimens received from patients with erythema migrans (EM), arthritis, and cardiac and neurological disorders were tested for antibodies to Borrelia burgdorferi. Sera from 499 patients were tested. Of these patients, 310 had neurological disease, 101 had carditis, 79 had arthropathies, and 9 had EM; for 35 patients, a diagnosis of Lyme disease was confirmed. Of these 35, 68% had neurological disease, 6% had carditis, and 26% had EM. Twelve probable cases of Lyme disease were noted. The male-to-female ratio of patients with confirmed or probable disease was 1.6; all age groups were represented, but 25% of patients were within the age group of 0-9 years. The number of cases of Lyme disease decreases from the north of Spain (41%) to the south (26%), a distribution that is in agreement with the known range of Ixodes ricinus. Borrelia burgdorferi is a frequent cause of infection in some areas of Spain. It is possible that relapsing fever accounts for some of the serological reactivity to B. burgdorferi in residents of the south of Spain.