Of the ten Bartonella species that are believed to produce infection in humans, the most commonly encountered are Bartonella henselae, B. quintana, and B. bacilliformis. The latter causes Oroya fever and Verruga peruana. Outbreaks are limited to the Andes and cases elsewhere have been found in travellers. B. quintana is the cause of Trench fever, which is found world-wide and causes febrile outbreaks. Poor sanitation and lack of personal hygiene strongly correlates with transmission by the body louse, Pediculis humanus. B. quintana is emerging as a recognised cause of disease amongst homeless people and AIDS sufferers. B. henselae is the cause of Cat Scratch Disease and is found throughout the world in association with domestic and feral cats. In the UK, B. henselae is considered to be endemic to the cat and dog population. Both the cat flea Ctenocephalides felis and Ixodid ticks are arthropod vectors.