Bartonella henselae as a cause of acute-onset febrile illness in cats

Breitschwerdt, Edward B; Broadhurst, Jack J; Cherry, Natalie A

An obvious limitation of this study is the inability to determine when and how B henselae transmission initially occurred and whether there was subsequent bacterial transmission within the household. Importantly, the onset of illness in cases 1 and 2 occurred months after presumptive flea transmission of B henselae, but shortly after the introduction of case 3. It is possible that fleas were unknowingly introduced into the household with case 3. In the context of disease causation, immediately following administration of azithromycin, all three cases became afebrile, supporting a diagnosis ex juvantibus ('from that which helps'; medical definition: 'a response to a narrow, specific therapy that strengthens the association with a suspected etiology'). Although B henselae bacteremia was documented in all three cats in conjunction with resolution of clinical signs following initiation of antibiotic therapy, it is possible that this response was related to another infectious agent (co-infection), or that spontaneous resolution of clinical signs occurred independently of antibiotic administration. However, based upon the results of this study and others published previously, 4-9 B henselae may be an underestimated cause of fever of unknown origin in flea-exposed cats, particularly those with immature or naive immune systems.