Bartonella resembles Rickettsia: both are minute, pleomorphic, Gram-negative and, although found intracellularly in vivo, are able to grow on solid media.^[1,2] Recent work has shown a link between Bartonella bacilliformis (the type species, the cause of Oroya fever and verruga peruana) and organisms variously thought to cause cat-scratch disease or bacillary angiomatosis (Bartonella henselae). B. bacilliformis is closely related to Bartonella (formerly Rochilimaea) quintana^[3] by 16S cDNA hybridization^[2] and to Brucella abortus, but a probe to detect a conserved region of B. bacilliformis by polymerase chain reaction from clinical specimens failed to recognize Brucella abortus.^[3] Bartonellae are sufficiently removed from the Brucella and Rickettsia to be considered a separate genus. An important property of bartonellae is chronic persistent or intermittent bacteraemia in the definitive host.