Bartonella
species are fastidious, Gram‐negative, coccobacillary or bacillary, small, arthropod‐borne bacteria that evolved from free‐living organisms and insect gut symbionts. This chapter focuses on the epidemiology, microbiology, clinical manifestations, and diagnosis of the three most common
Bartonella spp
;
B. bacilliformis
,
B. quintana
and
B. henselae
. Incidence of cat scratch disease is highest among those who live in the southern United States and among children 5 to 9 years of age. Trench fever, also known as 5‐day fever or quintan fever, is caused by
B. quintana
. Bacillary angiomatosis is characterized by neovascular proliferative lesions involving various organs. Infections caused by Bartonella spp. are uncommon among solid‐organ transplant recipients but both clinicians and clinical microbiologists should be aware of their unique characteristics.