Bartonella are obligate intracellular alpha-proteobacteria of the family Bartonellaceae. Cats and cat fleas serve as the main reservoir and as vectors of bartonellosis. At least one species, Bartonella vinsonii, is tick-transmitted. The antibody response to infections by Bartonella spp. is primarily directed against outer-membrane protein antigens and is most often detected using standard IFA and MIF methods.