Urban family cluster of spotted fever rickettsiosis linked to Rhipicephalus sanguineus infected with Rickettsia conorii subsp. caspia and Rickettsia massiliae

Abstract

Here, we report an epidemiological and entomological investigation of a cluster of cases of spotted fever group (SFG) rickettsiosis occurring in southern France. A family of 3 (husband, wife, and their son) presented with symptoms compatible with SFG rickettsiosis. For 2 patients, serum samples presented increased levels of IgM and IgG for SFG Rickettsia. The patients' home was investigated, and Rhipicephalus sanguineus ticks were collected from the floor from behind the furniture. Of 22 ticks collected, 20 tested positive for Rickettsia. As Rh. sanguineus serves as a vector for both Rickettsia conorii and Ri. massiliae in southern France, all Rh. sanguineus isolates were tested by real-time PCR and conventional PCR to detect the 2 species. Nine ticks tested positive for Ri. conorii subsp. caspia (marking the first documentation of this subspecies in France), 7 tested positive for Ri. massiliae, and 4 tested positive for both rickettsiae. This study is the first report of coinfection of Rh. sanguineus ticks with Ri. conorii and Ri. massiliae in southern France.