Summary

• Infectious disease caused by various species of the bacterial genus Bartonella; the three most important pathogens responsible for the majority of infections are B henselae, B quintana, and B bacilliformis.
• Some species are worldwide in distribution (B henselae), whereas others are geographically localised (B bacilliformis).
• Bartonella species are transmitted from an infected natural host to the susceptible human host either by direct contact (cat bite or scratch for B henselae) or via an insect vector (body lice for B quintana, sand fly for B bacilliformis).
• Bartonella species infect erythrocytes and cause vascular proliferation, giving rise to prolonged fever, lymphadenopathy, and hepatosplenomegaly.
• Laboratory diagnosis is established by culture, serology, or histopathology. Molecular techniques such as polymerase chain reaction (PCR) are useful for blood and tissue specimens, including heart valves, where available.
• Treatment depends on the species of Bartonella and the type of clinical presentation, but usually consists of antibiotic therapy. In some cases (e.g., cat-scratch disease), needle aspiration may be necessary.