Relevance of Bartonella henselae seropositivity in the feline patient

Bartonella henselae is a gram-negative bacterium that is most commonly associated with a self-limiting febrile condition in the cat lasting for two to three days. It has been suggested that bartonellosis is an arthropod transmitted disease, and there is an increased prevalence of the disease among flea-infested feral cats, especially kittens. Bartonellosis is a zoonotic disease and immunosuppressed humans such as people with HIV, those undergoing chemotherapy, or children, are particularly at risk. The route of transmission is mainly cat scratch or bite (SJ. Ettinger, EC. Feldman: Textbook of Veterinary Internal Medicine, 6th ed. Vol. 1, Pg 702).

It has been reported that Bartonella henselae has been associated with some of the "culture negative" infectious endocarditis cases (Figure 1). It is also associated with angiomatosis, meningitis, encephalitis and neuroretinitis in feline and human patients. Bartonella henselae was recently implicated in association with febrile conditions after routine surgical procedures (CE. Greene: Infectious diseases of the dog and cat, 2nd ed. Saunders, ppg. 337-343).

Figure 1: Vegetative mass on the aortic valve in a 5-year-old cat with infective endocarditis. The cat was Bartonella positive on serology.

In a study conducted in California, Bartonella spp. were found to be the most common bacteria in association with meningitis/encephalitis in cats. The symptoms included forebrain dysfunction (abnormal behavior, aggression, seizures), postural reaction deficits, myelopathy and neuropathy. In order to assess the significance of Bartonella seropositivity in feline patients with central nervous system disease, another study was designed and published recently as an abstract (LK. Pearce et al: Prevalence of Bartonella henselae specific antibodies in serum of cats with and without central nervous system disease in Abstract No. 218 from the 2005 ACVIM Forum).

In the abstract, the authors concluded that cats with neurological disease likely do not have more antibodies for Bartonella henselae then cats without neurological dysfunction. Thus, Bartonella titers (even those > 1:64) may not prove active disease caused by Bartonella henselae in the feline neurological patient. In this study, age and increased flea exposure did not influence the degree of seropositivity in cats with or without neurological symptoms.

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Cats with fever of unknown origin or suspected heart disease are candidates for bartonellosis. In these cases one should consider serological testing for Bartonella henselae and long-term (two to four weeks) treatment with antibiotics, such as amoxicillin-clavulanate, rifampin or doxycycline. The efficacy of any antibiotic has not been clearly established. Treatment failures are documented.

In summary, the significance of a positive Bartonella henselae titer is questionable in the feline patient with neurological signs, and this organism may not be responsible for the clinical signs. According to Greene (Infectious diseases of the dog and cat, 2nd ed. Saunders, ppg. 337-343) and Sykes (21st ACVIM Forum, 2003 Sharlotte, N.C. Proceedings ppg. 132-134) the diagnosis of Bartonellosis relies on positive serology titers, PCR, and blood or tissue cultures.

Dr. Nanai is a resident of the European College of Veterinary Neurology/Neurosurgery at the Animal Emergency andReferral Center in Fort Pierce, Fla.

Dr. Lyman is a graduate of The Ohio State University College of Veterinary Medicine. He completed a formal internship at the Animal Medical Center in New York City. Lyman is a co-author of chapters in the 2000 editions of Kirk’s Current Veterinary Therapy XIII and Quick Reference to Veterinary Medicine.