Acta Univ Latv (2003) 662: 7–15

Prevalence of various Borrelia burgdorferi sensu lato species in Ixodes ticks in three Baltic countries

Abstract

Borrelia burgdorferi sensu lato, a tick-borne spirochete, is the causative agent of Lyme disease, the most prevalent vector-borne disease in Europe and United States. However, the incidence of this disease is variable and the clinical picture depends on the pathogen species. The infectivity of Ixodes ticks with Borrelia, was 46 % and 35 % in 2000 and 2001 in Latvia, respectively, and 14 % in 2002 in Lithuania, assessed by nested polymerase chain reaction (PCR) amplification of the plasmid OspA gene fragment of Borrelia. PCR-restriction fragment length polymorphism (RFLP) analysis of the 16S-23S (rrs-rrlA) rRNA intergenic spacer was used for typing of Borrelia directly in ticks. Species-specifi c primers and subsequent sequences analysis were used as another approach for Borrelia species typing. All three clinically relevant B. burgdorferi sensu lato genospecies (B. afzelii, B. garinii, B. burgdorferi sensu stricto) were detected in the ticks collected in Latvia. The same result was obtained earlier in Estonia. B. valaisiana, a possible infectious agent of Lyme borreliosis, was detected only in Latvia. Only B. afzelii and B. garinii species were detected in ticks from Lithuania. Different subspecies were also identifi ed. This study demonstrates the predominance of the genospecies B. afzelii in all three Baltic countries, and the circulation of different B. burgdorferi sensu lato subspecies in the environment. This knowledge might have a significant importance for monitoring of Lyme disease in Europe.