Lyme borreliosis in Slovenia.

Basic epidemiological findings on Lyme borreliosis in Slovenia are presented. Data on vertebrate reservoir hosts are relatively modest. The presence of Borrelia burgdorferi sensu lato was demonstrated in about 20% of deer and 15-41% of examined small mammals. The presence of B. burgdorferi sensu lato was found by polymerase chain reaction in one half of 34 examined small mammals. Ixodes ricinus ticks have been found infected in all geographical regions of Slovenia examined till now. The highest infection rate was detected in the central part of Slovenia where almost 50% of adult ticks and one third of nymphs were positive by culture. The first isolation of B. burgdorferi sensu lato from material of Slovene patients succeeded in 1988 while the first isolates from ticks were obtained as late as 1993. The source material of human isolates has been skin, blood, cerebrospinal fluid, as well as synovial tissue and fluid. Thus far four Borrelia species were found by isolation to cause disease in humans: B. afzelii, B. garinii, B. burgdorferi sensu stricto, and B. bissettii. The majority of typed isolates belong to B. afzelii, but B. garinii slightly predominates among strains cultured from cerebrospinal fluid. Lyme borreliosis has been mandatory reportable in Slovenia for the last 11 years. It is the most common tick-borne disease and is present all over the country. The incidence has been increasing. In 1997 155/100,000 cases were recorded; in some regions the incidence was even substantially higher. The disease affects both sexes (as a rule more often women than men) and all age groups. The incidence is the highest in persons 30-50 years of age, followed by children aged 6-15 years. Erythema migrans is by far the most common recorded manifestation.