Rickettsiae of the spotted fever group associated with the host-parasite system Oryctolagus cuniculi/Rhipicephalus pusillus.

Wild rabbits--Oryctolagus cuniculi--living in large numbers in a protected zone of Tuscany, the park of Migliarino--San Rossore--Massaciuccoli, showed to be carriers of the hard tick Rhipicephalus pusillus, previously observed in North Africa and Sicily. Antibodies to Rickettsia conorii and R. slovaca were detected in 78.9 per cent of the wild rabbits captured in that area. Seroconversion towards R. conorii was also observed in guinea pigs inoculated with homogenates of R. pusillus parasitizing the wild rabbits. These results identify an ecological niche of rickettsiae of the Spotted fever group in the host-parasite system O. cuniculi/R. pusillus. Attempts to isolate rickettsiae from the ticks and the wild rabbits were unsuccessful both in the egg yolk sac and in the guinea pig. This failure probably shows the low pathogenicity of the rickettsiae parasitizing the biosystem O. cuniculi/R. pusillus.