Detection of multiple Bartonella species in digestive and reproductive tissues of fleas collected from sympatric mammals.

At least 12 species in the genus Bartonella are zoonotic pathogens that may be transmitted among mammalian hosts by fleas or other arthropods. Apparent host specificity by some Bartonella species to mammalian hosts has been observed, and the detection of multiple Bartonella species in mammalian fleas suggests that fleas take bloodmeals from a variety of host species. However, many flea species are observed to parasitize a narrow host range. Therefore, we suspect that fleas may acquire Bartonella by a mechanism other than ingesting infectious blood. We found that detection of multiple Bartonella genotypes and species is apparently common in fleas and that the majority of fleas tested (5/9) carried Bartonella species atypical of their hosts. We also detected Bartonella DNA in flea reproductive tissues, suggesting that vertical transmission of this organism in vectors is possible, potentially leading to the accumulation of Bartonella diversity over time within fleas.