LYME BORRELIOSIS SPIROCHETES IN IXODES-RICINUS (ACARI, IXODIDAE) AND THE VARYING HARE ON ISOLATED ISLANDS IN THE BALTIC-SEA

We investigated isolated ecosystems to determine if Lyme borreliosis i s maintained in the absence of reservoir-competent small mammals. Huma n cases of Lyme disease have been reported on the isolated islands of Gotska Sandon and Stora Karlso in tile Baltic Sea. The varying hare, L epus timidus, is the only terrestrial vertebrate species capable of se rving as a host for all stages of Ixodes ricinus (L;) on these islands . In August, mean larval infestation on 5 hares from each island was 5 48 with a maximum of 2,276 larvae on 1 ha! e. Smaller numbers of nymph al and female ticks were also engorging on the hares. During August-Se ptember B. burgdorferi s.l. was detected in 11-24% of nymphal I. ricin us fed as larvae on hares and in 8-19% of host-seeking nymphal I, rici nus collected from the vegetation. We conclude that L, timidus serves as a maintenance host for. B. burgdorferi s.l. and its vector; I. rici nus, on both islands.