Introduction

Cat scratch disease (CSD) was first described in 1950 by Rene Debré as “La Maladie de Griff de Chat.” Its cause remained a mystery until the late twentieth century, when amplification and sequencing of 16S rRNA genes was introduced as a method of identifying organisms that had not been successfully cultured. In 1992, David Relman and co-workers used this technique to identify the agent of CSD, and bacillary angiomatosis and parenchymal bacillary peliosis (BAP). He found that the causative organism was a small gram-negative coccobacillus closely related to the agents causing trench fever, brucellosis, and crown gall disease in plants (Agrobacterium tumefaciens).

The organism was first named Rochalimaea henselae, and was subsequently grouped within the family Bartonellaceae, along with a number of other organisms, including the agents of trench fever, Bartonella quintana (formerly Rochalimaea quintana). Bartonella bacilliformis, the agent of acute and chronic Carrión's disease is a related ancestor of modern members of the family Bartonellaceae. Recent reports suggest that similar clinical syndromes in the Andean highlands may also be caused by Bartonella rochalimae and possibly Candidatus Bartonella ancashi 20.0. These organisms, and probably others of the genus, share the ability to invade vascular endothelial cells, bone marrow erythroblasts, and mature erythrocytes. They also share the ability to induce macrophage-mediated secretion of proinflammatory cytokines (notably interleukin-10 [IL-10]) andvascular endothelial cell growth factor (VEGF) and the ability to suppress vascular endothelial cell apoptosis. These virulence factors give them the ability to disseminate within the host, causing proliferative vascular lesions and prolonged bacteremia in humans and mammalian reservoirs.