Bartonella are bacteria that live inside cells; they can infect humans and other mammals. It is mainly carried by cats and causes cat-scratch disease, endocarditis, and several other serious diseases in humans. Bartonella bacteria are known to be carried by fleas, body lice and ticks. Scientists suspect that ticks are a source of infection in some human cases of bartonellosis. People with tick bites and no known exposure to cats have acquired the disease.
For further information we refer you to:
Bartonella web pages at lymedisease.org
Columbia University's Lyme and Tick-Borne Diseases Research Center