Occurrence of Borrelia afzelii and Borrelia garinii in Ixodes ricinus ticks from southern Moravia, Czech Republic.

During the years 1996-2000, a total of 2398 Ixodes ricinus ticks were collected in three areas of southern Moravia and eastern Bohemia, Czech Republic, and examined by dark-field microscopy for the presence of spirochetes. The prevalence of B. burgdorferi sensu lato in Ixodes ricinus ticks varied and depended upon the year. In 1996, the prevalence 6.8% was observed, during 1997 and 1998, it increased to 8.4% and 12.3%, respectively. The lowest prevalence was observed in 1999 (3.6%), and in 2000 it increased to 4.0%. The mean rate of infection was 6.5%, and the proportions of infected ticks were 12.2% in 263 male ticks, 8.3% in 289 female ticks, 6.0% in 1621 nymphs, and 1.3% in 225 larvae. From the total of 156 highly infected ticks (>100 spirochetes per sample) transferred into BSK-H medium for isolation attempts, 13 isolates were obtained. PCR-RFLP and electrophoresis (SDS-PAGE) were used for the identification and characterization of Borrelia strains. Ten tick isolates were identified as Borrelia afzelii, and the other three isolates were found to be Borrelia garinii. The results indicate the epidemiological importance of B. afzelii and B. garinii in central Europe, and emphasize the role of I. ricinus in the ecology of B. burgdorferi and in the epidemiology and epizootiology of Lyme disease.