Prevalence of Borrelia burgdorferi s.I. in Ixodes ricinus ticks from Styria (Austria) and species identification by PCR-RFLP analysis.

A total of 1163 I. ricinus ticks were collected in 3 different regions (15 localities) in Styria (Austria) in June 1997 and examined for the presence of spirochetes by dark field microscopy. The mean infection rate was 20.8%. Among 310 adults, 24.2% were positive and among 853 nymphs, 19.6% were positive. All 15 collection areas were shown to harbour infected nymphs with a positivity rate ranging from 5.8% (3/52) to 32.1% (18/56). Isolation attempts in BSKII medium resulted in 29 isolates. Species identification by PCR-RFLP analysis revealed 16 strains of B. garinii, 10 strains of B. afzelii and 2 strains of B. burgdorferi s. s. One isolate showed a mixed population of B. garinii and B. afzelii. In two collection areas, all three major Borrelia species were shown to be present in the tick population.