Epidemiology and clinical manifestations of Lyme borreliosis.

Epidemiological and clinical characteristics of Lyme borreliosis (LB) in Sweden are described through a one year surveillance-study. The findings differed only marginally when compared to studies from the United States indicating similar clinical presentation of the disease. Incidence was 69/100.000/year with large variation between counties (26-160/100.000/year) and concentration of the disease to the south-eastern coast of Sweden. The incidence varied according to age in a bimodal pattern with the highest rates among those aged 5-9 or above 45 years. The most frequent manifestation was erythema migrans (EM; 77%), followed by neuroborreliosis (16%), arthritis (LA; 7%), acrodermatitis (3%), borrelial lymphocytoma (3%), and carditis (0.5%). Seasonal distribution showed tick-bites to be most frequent in July, whereas most cases of erythema migrans occured in August and other manifestations peaked in September. A population (n=540), from an area with the highest endemicity in the region, was followed during a three year period and studied with regard to the clinical manifestations and antibody prevalence of LB. At start 90/480 (19%) had IgG antibodies to Borrelia burgdorferi s.l. Subclinical infection dominated; 18 (4%) had a medical history of LB but late manifestations of the disease were found in several of the seropositive subjects when further examined. Based on musculoskeletal symptoms in 34/90 (38%) seropositive and in 48/390 (12%) of seronegative subjects (p