TICK ZOONOSES IN THE SOUTHERN PART OF SWITZERLAND (CANTON-TICINO) - OCCURRENCE OF BORRELIA-BURGDORFERI SENSU LATE AND RICKETTSIA SP

The diversity and the distribution of tick species and their infection rates by the pathogenic micro-organism Borrelia burgdorferi sensu lat e, the etiologic agent of Lyme borreliosis, and Rickettsia sp., were s tudied in Canton Ticino (the southern part of Switzerland). Ticks spec imens collected from animals and humans were classified and analysed f or the presence of both pathogens. In particular, PCR analysis was per formed for the detection of Borrelia spirochetes in Ixodes ricinus and Ixodes hexagonus, and the hemolymph test was done on Rhipicephalus sa nguineus for the detection of Rickettsia sp. PCR assays, performed on 424 of the 989 collected ticks, revealed a low rate of infection (arou nd 2%) of both vectors I. ricinus and I. hexagonus by B. burgdorferi s ensu late. These results are in agreement with the modest number of Ly me borreliosis cases yearly recorded in Ticino. Further, through analy sis of DNA sequences, the strains carried by the infected ticks were i dentified as belonging to the genomic group VS 116. The widespread fin ding of the Mediterranean species Rhipicephalus sanguineus in differen t locations from July 1994 to October 1995 demonstrates its establishm ent in Ticino. Of the 210 specimens collected, 70 were analysed and on e was infected by Rickettsia sp.