Bartonella spp. are aerobic, gram-negative pleomorphic
bacteria, belonging to the α2 subgroup of
the Proteobacteria. Many Bartonella spp. are pathogens
of humans, dogs, and cats. Numerous
domestic and wild animals can serve as chronically
infected reservoir hosts for Bartonella spp. An
increasing number of arthropod vectors have been
implicated in the transmission of Bartonella spp.
The main source of transmission to humans is
cats by means of scratches, whereas infection is less
likely to occur by cat bite. Most human cases of
infection with Bartonella henselae, named cat scratch
disease (CSD), present as an acute febrile lymphadenopathy.
The presence of cat fleas is essential
for the maintenance of the infection within the cat
population. The role of dogs as reservoirs of
Bartonella spp. is less clear, because they seem to
be only accidental hosts. Nevertheless, dogs are
excellent sentinels for human infections, because a
similar disease spectrum develops in dogs