In order to evaluate the role of the flea in the epidemiology of B. henselae infection, five young cats were kept in confinement for two years, one of which was inoculated with B. henselae (105 CFU) subcutaneously when it was six months old. Fleas were allowed to exist on the cats throughout that period. Blood culture for isolation of bacteria, PCR using HSP, FTSZ and BH-PCR protocols and indirect immunofluorescence (IFI) for anti-B. henselae antibodies were performed to confirm the initial infection of the first cat and subsequent infection of the other naive cats mantained in the same environment. B. henselae could be isolated by blood culture two months after inoculation and lasted for four months in the first cat; the specific antibodies could be detected by IFI during the period of bacteremia. All animals in contact with the infected cat showed bacteremia 6 months after the original cat was inoculated, but seroconversion could not be shown. Any genetic material could be amplified from the peripheral blood of all the cats using PCR protocols. However, all isolates were characterized as Bartonella (HSP and FTSZ-PCR protocols) and henselae (BH-PCR protocols). These results highlighted the role of fleas in the epidemiology of B. henselae infection in cats and the blood culture as the most efficient method for detection of infection, when compared to PCR or IFI.