Acquisition of the Cat Scratch Disease Agent Bartonella henselae by Cat Fleas (Siphonaptera: Pulicidae)

We assayed the ability of cat fleas to become infected with Bartonella henselae , using an artificial feeding device. Fleas fed a concentration of 1 X 105 cfu/ml in blood were examined using immunofluorescent antibody assay and polymerase chain reaction. Bacteria were present in the gut at 3 h, and persisted up to 9 d after infection. Qualitatively, the density of B. henselae was greater in the flea gut at 9 d, indicating that replication was occurring in the gut. B. henselae also was detected in the feces of infected fleas 9 d after infection, and produced viable colonies upon inoculation onto heart infusion agar/rabbit blood plates. Our results indicate that fleas can maintain infection with B. henselae , and may play a role in the transmission of this bacterium from infected cats to humans.