Feline bartonellosis and cat scratch disease.

Bartonella species are important emerging zoonotic pathogens. Transmission of these organisms in nature may be much more complex than is currently appreciated. Cats can be infected with five Bartonella species, including, Bartonella henselae, Bartonella clarridgeae, Bartonella bovis, Bartonella koehlerae and Bartonella quintana. In addition to cats, numerous domestic and wild animals, including bovine, canine, human, and rodent species can serve as chronically infected reservoir hosts for various intra-erythrocytic Bartonella species. In addition, an increasing number of arthropod vectors, including biting flies, fleas, keds, lice, sandflys and potentially ticks have been implicated in the transmission of various Bartonella species to animals or human beings. In the reservoir host, Bartonella species cause chronic intra-erythrocytic and vascular endothelial infections, with a relapsing bacteremia documented in experimentally infected cats. Although the immunopathology induced by Bartonella infection requires additional study, the organisms can localize to the heart valve (endocarditis), cause granulomatous inflammation in lymph nodes, liver or spleen, induce central nervous system dysfunction with or without cerebrospinal fluid changes, and may contribute to inflammatory polyarthritis. Hematological abnormalities are infrequent, but thrombocytopenia, lymphocytosis, neutropenia, and eosinophilia have been reported in B. henselae-infected cats. Serology, PCR and culture can be used to support a diagnosis of feline bartonellosis, however, due to the high rate of sub-clinical infections among various cat populations, documenting causation in an individual cat is difficult, if not impossible. Response to treatment can be used in conjunction with serology or organism isolation to support a clinical diagnosis of feline bartonellosis. As fleas are involved in the transmission among cats, the use of acaracide products to eliminate fleas from the environment is of critical importance to decrease the risk of B. henselae transmission among cats and to humans.