CLINICAL MANIFESTATIONS AND ANTIBODY PREVALENCE OF LYME BORRELIOSIS AND TICK-BORNE ENCEPHALITIS IN SWEDEN - A STUDY IN 5 ENDEMIC AREAS CLOSE TO STOCKHOLM

Five populations, including 903 individuals living in 5 different area s close to Stockholm, were studied with regard to clinical manifestati ons and antibody prevalence of Lyme borreliosis (LB) and tick-borne en cephalitis (TBE). The study areas involved 4 groups of islands in the Baltic Sea and 1 island in Lake Malaren. Serum samples from each indiv idual were tested for antibody activity to Borrelia burgdorferi using a sonicated whole spirochete antigen in an ELISA, and to TBE-virus (TB EV) by ELISA and haemagglutination inhibition. A history of LB was rep orted by 1-21% and antibodies to Borrelia burgdorferi were found in 7- 29% of the participants from the various areas. An increasing seroprev alence with age was seen. In sera from 3 different control groups, inc luding 502 individuals living in non-endemic areas, antibodies to Borr elia burgdorferi were detected in 1-2% and from 1 control group includ ing 150 individuals living in the city of Stockholm, in 9%. A history of TBE was reported by 0-6% of the individuals and in non-immunized in dividuals seropositivity was seen in 4-22%, depending on the area inve stigated. No antibody activity to TBEV could be detected in sera from persons in the 3 control groups living in non-endemic areas, whereas 5 % of the controls from Stockholm were found to be positive. The preval ence rates of antibodies to TBEV in persons vaccinated against TBE wer e 40%, 53% and 79% after 1, 2 and 3 injections, respectively.