A New Rickettsia Species Found in Fleas Collected from Human Dwellings and from Domestic Cats and Dogs in Senegal

The insects of the order Siphonaptera, commonly named fleas, are vectors of pathogens around the world. Our previous studies showed that 4.4% of acute febrile diseases in the Sine-Saloum region of Senegal were due to Rickettsia felis. The aim of this study was to explain the high prevalence of R. felis infections in two rural Senegalese populations by an entomological, systematic monitoring protocol. A total of 232 fleas from three species (Ctenocephalides felis, Echidnophaga gallinacea, and Synosternus pallidus) were collected by candle trapping and manually from pets in the villages of Dielmo and Ndiop during the year 2010. The fleas were then tested for the presence of Bartonella and Rickettsia species. No fleas were found to be positive for any Bartonella species or R. felis. Surprisingly, we found that 91.4% of S. pallidus were infected by a new Rickettsia species, which, based on sequence analysis of gltA, ompB, and two fragments of rpoB, was found to be closely related to R. felis. The results from this study did not explain the high incidence of R. felis infections in these Senegalese populations.