Detection and identification of spotted fever group rickettsiae in ticks collected in southern Croatia.

A total of 197 ticks belonging to four species (Haemaphysalis punctata, Hyalomma marginatum, Rhipicephalus bursa and Dermacentor marginatus) collected in October 2000 from domestic animals in southern Croatia were examined for the presence of rickettsiae by molecular techniques. Specific sequences of the rickettsiae were detected in 25 (12.7%) of ticks tested. The prevalence of infection in D. marginatus and H. marginatum ticks was 36.8 and 64.7%, respectively. None of the ticks belonging to the species H. punctata or Rh. bursa were infected. Sequence analysis of amplified products revealed that D. marginatus ticks are infected with Rickettsia slovaca, whereas H. marginatum are infected with R. aeschlimannii. The results of this study extend the knowledge of the geographic distribution of SFG rickettsiae and indicate that at least two of them, with yet uncertain pathogenicity to humans, are present in ticks in southern Croatia.