[Preliminary studies on the occurrence of Rickettsiae of the spotted fever group in Rhipicephalus sanguineus captured in suburban areas].

In the urban periphery of Rome, two sub-zones could be distinguished, characterized by uncultivated steppeland and by small shacks with large quantities of domestic refuse, respectively. Rhipicephalus sanguineus appeared to be typical of this second sub-zone. R. sanguineus adults and nymphae were captured in different seasonal periods and were checked for the prevalence of rickettsiae of the Spotted Fever (SF) group. Moreover, larvae from hatched eggs, laid by captured R. sanguineus females, were checked for the transovarial transmission of rickettsiae. Ten lots each of three guinea-pigs, seronegative to rickettsiae of the SF group, were inoculated with R. sanguineus extracts, prepared from adults or larvae. Clinical signs of infection, fever and scrotal reaction, could be observed only in one lot of guinea-pigs inoculated with adult parasites. On the other hand, in 8 out of 10 guinea pig lots, antibodies to the soluble antigens of R. conori and R. slovaca were observed by the complement fixation (CF) test. In the remaining two lots only antibodies to R. slovaca were detected. No antibodies to Coxiella burneti could be demonstrated in the same sera.