Bartonellosis is an important emerging disease in humans and has been recognized to cause clinical disease in several other species, including dogs and cats.
• Update on Bartonella spp as a "rediscovered" etiologic agent in human, canine and feline disease
• Discuss etiology and epidemiology of Bartonella spp in our feline population
• Provide results of a study evaluating the association between feline stomatitis and bartonellosis
• Bartonella spp. are being recognized as re-emerging human pathogens
• The zoonotic potential of Bartonella spp. makes this an important concern for cat owners
• The majority of cats with bartonellosis are asymptomatic
• Bartonella spp. have been the proposed etiologic agents resulting in clinical signs in cats, including uveitis, endocarditis, gingivitis, stomatitis, and lymphadenopathy.
• The high prevalence rate of Bartonella positive in healthy cats makes it difficult to determine cause and effect of disease relative to Bartonella status
• Preliminary results suggest that there is not an association between Bartonella and stomatitis
• Other infectious or immune causes of stomatitis should be considered prior to specific anti-Bartonella therapy
Bartonellosis is an important emerging disease in humans and has been recognized to cause clinical disease in several other species, including dogs and cats. Bartonella henselae is the primary etiologic agent in Cat Scratch Disease, which causes fever and lymphadenopathy in humans. Bartonella spp. can result in more serious pathology in humans including bacillary angiomatosis and bacillary peliosis, especially in immunosuppressed individuals. For these reasons, Bartonella spp. pose a zoonotic risk. Cats are often asymptomatic carriers for B. henselae and B. clarridgeiae. Whether these agents, or other Bartonella spp., cause clinical disease in cats is currently being investigated.
Bartonella spp. are transmitted primarily via arthropod vectors, which vary depending on the species. Fleas are thought to be the primary vector for Bartonella henselae and B. clarridgeiae in cats, which is supported by the higher prevalence of Bartonella positive cats from flea regions. Cats may clear the organism, but may also become asymptomatic carriers with intermittent episodes of bacteremia. Seroprevalence rates range from 5% - 90% of cats, depending on the region of interest.
Chronic, intracellular bacteria can induce over-exuberant host responses and so the supposition that Bartonella spp., which may not always be cleared by the feline host, could induce the lymphocytic-plasmacytic lesions indicative of stomatitis and other immune-reactive diseases. Several studies have evaluated the correlation between Bartonella spp and hemolytic anemia, uveitis and endocarditis. The majority of studies have either shown no significant difference between healthy cat populations and affected cats with regard to Bartonella antibody titers and amplification of organism DNA using PCR, or are single case reports of disease association. A case report of a cat with vegetative endocarditis identified B. henselae via PCR performed on the affected aortic valve, but blood cultures from the cat were negative. Similarly, the aqueous humor of client-owned cats with uveitis, cats experimentally infected with Bartonella spp and healthy shelter cats with normal ocular exams was evaluated via IgG titers and PCR. Some of the cats with uveitis and those experimentally infected with Bartonella spp showed evidence of intraocular production of antibodies as well as organismal DNA in 3 cats out of 24 with uveitis, while only one of the 49 healthy cats had Bartonella DNA present in the aqueous humour without IgG production. There was no statistical difference among the groups, but numbers in groups may have been too small to detect such differences. Therefore, it is possible that some cases of uveitis may be caused by Bartonella spp.
Several etiologic agents have been implicated as potential causes of stomatitis. Oral bacteria, calicivirus, FeLV/FIV are the most commonly sited causes, but direct cause-and-effect evidence is lacking. It is likely that the etiology is multifactorial and may involve host factors, such as an impaired immune response. Several reports have identified higher prevalence rates of stomatitis in cats infected with both FIV and Bartonella spp. Some veterinary laboratories are recommending screening of all cats with stomatitis or other vague clinical signs for Bartonella spp. antibody titers.
A recent abstract suggested no significant difference between healthy cats without stomatitis and cats with stomatitis with regard to their Bartonella antibody titers or PCR status. The prevalence of positive Bartonella spp. serum antibody titers was 67.6% (affected cats) and 58.8% (healthy cats) and both groups had a prevalence rate of 8.89% for PCR positive samples. There was no statistically significant difference in either the Bartonella spp. antibody titers or the positive PCR assays between the affected cats and the healthy cats. The only correlation to stomatitis was in affected cats with a history of upper respiratory infection (URI). Our own unpublished data evaluating cats with stomatitis compared to healthy cats living in areas with high risk for feline calicivirus (FCV) found a significantly higher number of FCV (by PCR) in stomatitis cats than in the controls. Further investigation of viral and bacterial causes of feline URI as a cause of stomatitis seems warranted.
When screening cats using Bartonella spp. serum antibody titers, the veterinarian must keep in mind the high prevalence rates in healthy cats. High titers do not equal active disease. Given the difficulty of making a definitive diagnosis of bartonellosis in a cat, treatment is usually recommended after all other causes of clinical signs have been ruled-out. Doxycycline, enrofloxacin and azithromycin have been used in human infections and their use has been extrapolated to cats. In both humans and cats, treatment duration and response to therapy is quite variable and clearance of the organism is not guaranteed. Therefore, as stated by the American Association of Feline Practitioners Bartonella Consensus statement, treatment should be limited to positive cats owned by immunocompromised people or as an alternative to euthanasia in a sick cat whose signs could be attributable to a Bartonella spp. infection.
Kordick DL, Brown TT, Shin K, Breitschwerdt EB. Clinical and pathologic evaluation of chronic Bartonella henselae or Bartonella clarridgeiae infections in cats. J Clin Microbio 1999; 39:1536-1547.
Chomel BB, Kasten RW, Sykes JE, et al. Clinical impact of persistent Bartonella bacteremia in humans and animals. Ann NY Acad Sci 2003;990:267-278.
Chomel BB, Wey AC, Kasten RW, et al. Fatal case of endocarditis associated with Bartonella henselae type I Infection in a domestic cat. J Clin Microbio 2003;41:5337-5339.
Lappin MR, Kordick DL, Breitschwerdt EB. Bartonella spp. antibodies and DNA in aqueous humour of cats. J Fel Med & Surg 2000;2:61-68.
Dowers KL, Lappin MR. The association of Bartonella spp. infection with chronic stomatitis in cats (Abstract). J Vet Int Med 2005:19;471.
Brunt J, Guptill J, Kordick DL, Kudrak S, Lappin MR. American Association of Feline Practitioners 2006 Panel report on diagnosis, treatment and prevention of Bartonella spp. infections. J Fel Med & Surg 2006;8:213-226.