IDENTIFICATION OF SPOTTED-FEVER GROUP RICKETTSIAE ISOLATED FROM DERMACENTOR MARGINATUS AND IXODES-RICINUS TICKS COLLECTED IN SWITZERLAND

When 155 ticks collected in different regions of Switzerland were test ed by the hemolymph test, 10.3% were found to contain spotted fever gr oup rickettsiae. Six rickettsial isolates were made from Dermacentor m arginatus ticks and three were made from Ixodes ricinus ticks. The pol ymerase chain reaction followed by restriction fragment length polymor phism analysis showed that the Dermacentor ticks were infected with Ri ckettsia slovaca and the Ixodes ticks were infected with a spotted fev er group rickettsia. Microimmunofluorescence serologic typing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins, and We stern blot assay with polyclonal mouse antisera confirmed the results and determined that the Ixodes were infected with R. helvetica, the on ly previously described Swiss rickettsia. However, an additional new s train that could not be isolated was detected in one I. ricinus by hem olymph test and provisionally characterized by enzymatic restriction o f its amplified DNA.