PATHOGENS

Bartonella spp. are haemotropic gram-negative bacteria within the family Bartonellaceae that are mainly transmitted by vectors. A characteristic feature of these bacteria is their adherence to and invasion of erythrocytes, causing a long lasting intra-erythrocytic bacteraemia and endotheliotropic infection.

The widespread occurrence and diversity of these bacteria has been increasingly recognised and resulted in expansion of the genus Bartonella to more than 35 currently described species and over 15 Candidatus species (Breitschwerdt, 2017). Many Bartonella species appear to be well-adapted to extended survival in mammalian reservoir hosts, often without causing symptomatic disease.

While cats are considered to be the main mammalian reservoir for important zoonotic Bartonella species (Bartonella henselae, Bartonella clarridgeiae and Bartonella koehlerae), the role of dogs as a reservoir is less clear. Current evidence indicates that canids – including coyotes, dogs and grey foxes – potentially serve as reservoir hosts for Bartonella vinsonii subsp. berkhoffii. Furthermore, the presence of Bartonella rochalimae in dogs, grey and red foxes, raccoons and coyotes, as well as in fleas collected on grey foxes, indicates that carnivores may function as natural reservoirs of this zoonotic Bartonella species, with fleas being suspected as the main vector.

Species known to infect dogs are B. vinsonii subsp. berkhoffii and B. henselae, which also seem to be the most likely species to be associated with clinical disease in dogs. Infections with B. clarridgeiae, Bartonella washoensis, Bartonella elizabethae, B. koehlerae and Bartonella quintana have also been reported.

Several Bartonella species have been identified as zoonotic pathogens including B. henselae and B. vinsonii subsp. berkhoffii.

For a comprehensive overview on Bartonella species and their reservoirs see Breitschwerdt (2017).