What do we really know about feline bartonellosis? (Proceedings)


Bartonella infections of domestic cats have only recently been recognized, but likely have existed for thousands of years.

Bartonella infections of domestic cats have only recently been recognized, but likely have existed for thousands of years. Bartonella DNA was recently detected by polymerase chain reaction (PCR) in 800-year-old dental material from cats and in 4000-year-old dental material from a human being. The first report of Bartonella infection of a cat appeared in 1992, and many clinical and experimental studies of feline bartonellosis have followed. Several Bartonellae are zoonotic human pathogens. Zoonotic species include Bartonella henselae, Bartonella vinsonii subsp. berkhoffii, B. vinsonii subsp. arupensis, B. washoensis, B. elizabethae, B. koehlerae, B. clarridgeiae, and B. quintana. Bartonella quintana, a cause of trench fever, endocarditis, bacillary angiomatosis, and other conditions, and B. henselae, a cause of cat scratch disease, bacillary angiomatosis, endocarditis, and other conditions, are the most well known of these zoonotic pathogens. Cat scratch disease has been recognized in human beings as a specific disease entity for over 50 years, and references to similar conditions can be found as far back as the 17th century. Many other manifestations of zoonotic bartonellosis (such as parenchymal bacillary peliosis, relapsing fever with bacteremia, optic neuritis, pulmonary, hepatic, or splenic granulomas, osteomyelitis and others) are reported. Immunocompetent individuals tend to have more localized and self-limiting infections, whereas infections that occur in immunocompromised individuals are more often systemic and can be fatal without treatment. Veterinarians, veterinary staff, groomers, and other individuals with extensive animal contact appear to be at a greater risk for Bartonella infection than others.

Cats are recognized as the primary reservoir and vector for zoonotic B. henselae infections, and have also been implicated as vectors for B. clarridgeiae infection of people. Cats may also be reservoirs and vectors of B. koehlerae and other Bartonella species as well. Transmission of B. henselae from cats to human beings probably occurs through contamination of cat scratches or other wounds, or mucous membranes such as conjunctiva, with flea excrement. Transmission may occur via cat bites if cat blood or flea excrement contaminate the bite site. Bartonella henselae is transmitted among cats by fleas. Viable Bartonella organisms are excreted in flea feces and cats are likely inoculated via contamination of wounds or mucous membranes with infected flea feces. The role of the flea as a vector for transmission to human beings is not clear, but transmission via flea feces is considered likely. Ticks are another possible vector. Viable Bartonella spp. have been detected in questing ticks; also in other arthropod vectors including biting flies and sheep keds.

Cats infected with B. henselae may have relapsing bacteremia for months to years, and relapsing bacteremia is suspected in cats infected with other Bartonella species. Bacteremia appears to be more common in young cats (<2-3 years of age) and older cats are more likely to be seropositive. How long serum antibodies persist following clearance of infection is unknown. Experimental data indicate that serum antibodies persist for months to years following apparent clearance of bacteremia. Bacteremia in cats is more prevalent in regions with warm, humid climates where flea infestations are more common. In some regions, prevalence of serum antibodies to B. henselae in cats is reportedly as high as 75-90%.

Clinical manifestations

Most cats with Bartonella bacteremia appear to be clinically normal. Some cats experimentally infected with B. henselae or B. clarridgeiae exhibited mild and transient clinical signs including fever, lethargy, anorexia, and lymphadenomegaly. Uncommon signs included central nervous system signs (nystagmus, tremors, or possible focal motor seizures), myalgia or reproductive failure. There is great genetic diversity among B. henselae isolates, and clinical signs in experimentally infected cats varied with the isolates used for inoculation. Many tissues of cats experimentally infected with B. henselae and B. clarridgeiae had multiple foci of inflammatory cells. Many naturally infected cats do not exhibit obvious clinical signs, but may have lymphadenomegaly or transient fever. Fatal endocarditis was reported in one cat naturally infected with B. henselae. No clinical signs were reported in cats experimentally or naturally infected with B. koehlerae or B. bovis. Cats infected with B. henselae or B. clarridgeiae have relapsing bacteremia, and relapsing bacteremia is suspected in cats infected with other Bartonella species. It has been suggested that several other conditions of cats, particularly some chronic conditions heretofore considered idiopathic, may be related to Bartonella infection. Although it is possible that Bartonella infections may play a role in development of some of these conditions, there are no published controlled studies verifying a causal association of Bartonella infection with specific disease conditions. Recent studies have failed to demonstrate an association between Bartonella infection in cats and stomatitis, neurologic disease, or uveitis. Because of the high prevalence of Bartonella infection in the domestic cat population, large, appropriately controlled studies are necessary to determine what causal associations may exist between Bartonella infections and clinical conditions of cats.


Culture of Bartonella from blood or other tissues provides a definitive diagnosis of Bartonella infection in cats, and is the criterion standard against which other means of diagnosis are measured. As a result of relapsing bacteremia, blood culture may yield false negative results in cats infected with Bartonella spp. The Vector Borne Disease Laboratory at North Carolina State University has reported some increased sensitivity using a specialized enrichment medium for Bartonella culture. Amplification of DNA from peripheral blood by standard polymerase chain reaction (PCR) assay may be no more sensitive for detection of Bartonella bacteremia than standard culture if blood is sampled when a cat is temporarily abacteremic or has a very low level of bacteremia. Nested or real-time PCR assays may be more sensitive than standard PCR assays. While polymerase chain reaction assays are very sensitive for detection of bacterial DNA, they do not distinguish between DNA of living and dead organisms. Other pitfalls of PCR assays are that there may be false positive results following contamination of samples, and false negative results due to degradation of nucleic acids related to collection methods, transport, storage, or handling. Benefits of PCR assays are their sensitivity, short turnaround time, and species-specific diagnosis through sequencing of the PCR products. Since cats may be infected with multiple Bartonella species, consideration should be given to including broad range primers or primers for multiple species when performing PCR testing. Laboratories should be contacted for specific instructions for sample collection and shipment for culture or PCR assays. Strict sterile collection technique is required when samples are collected for PCR assay.

There are not clear criteria for establishing a diagnosis of bartonellosis in cats using serological methods. Immunofluorescent antibody (IFA), enzyme immunoassay (EIA), and Western blots are used for detection of anti-Bartonella serum antibodies. Positive predictive values of IFA and EIA techniques for bacteremia are low (~42-46%) but the negative predictive values are higher (~90-93%). Therefore, it has been suggested that serologic testing may be a useful screening tool for identifying a cat that is unlikely to be infected with Bartonella. Approximately 5 - 12% of bacteremic cats were serologically negative with IFA or EIA tests. These cats may have been tested early in infection before serum antibodies developed, or may not have developed detectable serum antibodies to the bacteria. No specific reciprocal titer or range of titers has been reported as having a high predictive value for bacteremia. Predictive values are not well established for Western blot assays. In addition, it is not known how long serum antibody titers persist following clearance of Bartonella infection, and it can be difficult to document clearance of Bartonella infection. Because of the genetic diversity of Bartonella organisms, infections with some strains or species of Bartonella may be missed using any serological method. Seroreactivity may depend on the antigen preparations and detection systems used.

Co-infection with other pathogens

Cats may be co-infected with multiple species of Bartonella and with multiple rRNA types of B. henselae. Cats may also be co-infected with Bartonella spp., other vector-transmitted pathogens, and/or other pathogens such as feline leukemia virus, feline immunodeficiency virus (FIV), or hemotrophic mycoplasmas. Cats seropositive (actual infection status was unknown) for B. henselae and FIV reportedly had more severe lymphadenopathy or gingivitis than cats positive for Bartonella or FIV alone. Co-infection with multiple pathogens makes it difficult to attribute clinical signs of disease to infection with a particular organism, and also confounds interpretation of response to treatment.

Treatment and prevention

The current consensus is that due to the possibility of development of antibiotic resistance (not only among Bartonella isolates, but also among other bacteria) only cats exhibiting clinical signs of Bartonella infection should be treated with antibiotics. Results of several published studies describing the use of antibiotics to treat Bartonella infections in cats demonstrate that true clearance of Bartonella infections is probably difficult to accomplish with any antibiotic treatment, and difficult to document. Prolonged follow up testing of treated cats is needed to verify clearance of infection due to the prolonged, relapsing bacteremias reported, and some published experimental studies had limited follow-up times of 2 weeks to 6 weeks. Antibiotics used in published studies included erythromycin, tetracycline, doxycycline, amoxicillin/clavulanic acid, rifampin, enrofloxacin, and some combinations of these drugs. No single drug or drug combination was shown to routinely clear infection. Currently, azithromycin is often recommended for treatment of infected cats, but there is no published, randomized, controlled study documenting its efficacy. Use of any antibiotic appears to decrease the level of bacteremia in infected cats. When considering treatment, the possibility of co-infection with multiple pathogens should be investigated, and cats treated accordingly. Other possible causes of clinical signs in cats seroreactive to Bartonella antigens should be thoroughly pursued before specific treatment for Bartonella is considered. Because the prevalence of Bartonella seroreactivity is high in domestic cats, clinical conditions may be erroneously attributed to Bartonella infection. If other causes of clinical signs in ill cats are identified, treatment for those entities should be undertaken prior to administering antibiotic treatments for Bartonella. Treatment of healthy cats belonging to immunocompromised clients is sometimes suggested, but until a very effective treatment is demonstrated this is not advised as a routine practice. Cats that are treated for or spontaneously clear Bartonella infection are not necessarily protected from future infections. Vector control remains the best means of preventing Bartonella infections in cats. Therefore precautions such as excellent vector control programs and avoiding scratch or bite wounds must be taken to prevent zoonotic transmission.

Public health

The United States Public Health Service/Infectious Diseases Society of America (USPHS/IDSA) Guidelines for Preventing Opportunistic Infections Among HIV-Infected Persons recommend the following when acquiring a new cat: adopt a cat over 1 year of age that is in good health, avoid rough play with cats, maintain flea control, wash any cat-associated wounds promptly, and do not allow a cat to lick wounds or cuts. There is no direct evidence that declawing cats decreases the probability of transmission of B. henselae from cats to human beings. The USPHS/IDSA Guidelines state that there is no evidence of any benefit to cats or their owners from routine culture or serologic testing of cats for Bartonella infections. However, because the negative predictive value of B. henselae serologic test results for feline bacteremia is very good, serology may in some situations be an appropriate screening test for cats that immunocompromised persons are considering as pets, with the recommendation that only seronegative cats be acquired. Nonetheless, there is still an approximately 10-15% probability that a seronegative cat is infected with Bartonella.

Control of arthropod vectors, and avoidance of animal bites and scratches, are the most important and the most effective preventive measures currently available to avoid transmission of Bartonella infections from animals to human beings.

What do we know?

Bartonellas have been associated with their reservoir hosts for many years

Clinical conditions Bartonella infections caused in cats are not well defined

Diagnosis of Bartonella infection of cats is challenging due to relapsing bacteremia and apparent persistence of serum antibodies– development of diagnostic tests that are both very sensitive and very specific is needed

Cats can be repeatedly infected with Bartonella spp.

Treatment of Bartonella infections of cats is challenging – further controlled studies are needed

Treatment of Bartonella infection is generally not indicated in healthy cats, but rather in ill cats when other causes of clinical conditions are ruled out

Preventing transmission of Bartonella infections of and by cats is best accomplished by vector control, and it is important to implement and maintain excellent vector control programs. Also important in preventing transmission of Bartonella infection from cats to human beings are such common sense precautions as avoiding cat scratches and bites, promptly washing any cat associated injuries, and seeking medical attention when indicated.


1. Aboudharam G, Dang La V, Davoust B, Drancourt M, Raoult D, Molecular detection of Bartonella spp. in the dental pulp of stray cats buried for a year, Microbial Pathog 2005; 38: 47-51

2. Arvand M, Klose AJ, Schwartz-Porsche D, Hahn H, Wendt C (2001), Genetic variability and prevalence of Bartonella henselae in cats in Berlin, Germany, and analysis of its genetic relatedness to a strain from Berlin that is pathogenic for humans, J Clin Microbiol 39: 743-746

3. Arvand M, Viezens J, Berghoff J, Prolonged Bartonella henselae bacteremia caused by reinfection in cats, Emerg Infect Dis 2007; 14:152-4

4. Avidor B, Graidy M, Efrat B, et al. Bartonella koehlerae, a new cat-associated agent of culture-negative human endocarditis, J Clin Microbiol 2004; 42: 3462-3468

5. Baneth G, Kordick DL, Hegarty BC, Breitschwerdt EB, Comparative seroreactivity to Bartonella henselae and Bartonella quintana among cats from Israel and North Carolina, Vet Microbiol 1996; 50: 95-103

6. Birtles RJ, Laycock M, Kenny MJ, Shaw SE, Day MJ, Prevalence of Bartonella species causing bacteremia in domesticated and companion animals in the United Kingdom, Vet Rec 2002; 151: 225-229

7. Breitschwerdt EB, Levine JF, Radulovic S, et al. Bartonella henselae and Rickettsia Seroactivity in a Sick Cat Population from North Carolina, Int J Appl Res Vet Med 2005; 3: 287-302

8. Breitschwerdt EB, Feline bartonellosis and cat scratch disease, Vet Immunol Immunopathol 2008; 123:167-71

9. Chang C-C, Chomel BB, Kasten RW, Tappero JW, Sanchez MA, Koehler JE, Molecular epidemiology of Bartonella henselae infection in human immunodeficiency virus-infected patients and their cat contacts, using pulsed-field gel electrophoresis and genotyping, J Infect Dis 2002; 186: 1733-1739

10. Chomel BB, Abbott RC, Kasten RW, et al., Bartonella henselae prevalence in domestic cats in California: Risk factors and association between bacteremia and antibody titers, J Clin Microbiol 1995; 33: 2445-2450

11. Chomel BB, Boulouis H-J, Breitschwerdt EB, Cat scratch disease and other zoonotic Bartonella infections, J Am Vet Med Assoc 2004; 224: 1270-1279

12. Chomel BB, Kasten RW, Floyd-Hawkins KA, et al. Experimental transmission of Bartonella henselae by the cat flea, J Clin Microbiol 1996; 34: 1952-1956

13. Chomel BB, Wey AC, Kasten RW, Stacy BA, Labelle P, Fatal case of endocarditis associated with Bartonella henselae type I infection in a domestic cat, J Clin Microbiol 2003; 41: 5337-5339

14. Droz S, Chi B, Horn E, Steigerwalt AG, Whitney AM, Brenner DJ, Bartonella koehlerae sp. nov., isolated from cats, J Clin Microbiol 1999; 37: 1117-1122

15. Finkelstein JL, Brown TP, O'Reilly KL, Wedincamp jrJ, Foil LD, Studies on the growth of Bartonella henselae in the cat flea, J Med Entomol 2002; 39: 915-919

16. Foil L, Andress E, Freeland R, et al. Experimental infection of domestic cats with Bartonella henselae by inoculation of Ctenocephalides felis (Siphonaptera: Pulicidae) feces, J Med Entomol 1999; 35: 625-628

17. Freeland RL, Scholl DT, Rohde KR, Shelton DG, O'Reilly KL, Identification of Bartonella-specific immunodominant antigens recognized by the feline humoral immune system, Clin Diagn Lab Immunol 1999; 6: 558-566

18. Greene CE, McDermott M, Jameson PH, Atkins CL, Marks AM, Bartonella henselae infection in cats: Evaluation during primary infection, treatment, and rechallenge infection, J Clin Microbiol 1996; 34: 1682-1685

19. Guptill L, Slater L, Wu C-C, et al. Immune response of neonatal specific pathogen-free cats to experimental infection with Bartonella henselae, Vet Immunol Immunopathol 1999; 71: 233-243

20. Guptill L, Slater L, Wu C-C, et al. Experimental infection of young specific pathogen-free cats with Bartonella henselae, J Infect Dis 1997; 176: 206-216

21. Guptill L, Slater L, Wu C-C, et al. Evidence of reproductive failure and lack of perinatal transmission of Bartonella henselae in experimentally infected cats, Vet Immunol Immunopathol 1998; 65: 177-189

22. Guptill L, Wu C-C, HogenEsch H, et al. Prevalence, risk factors, and genetic diversity of Bartonella henselae infections in pet cats in four regions of the United States, J Clin Microbiol 2004; 42: 652-659

23. Gurfield AN, Boulouis H-J, Chomel BB, et al. Coinfection with Bartonella clarridgeiae and Bartonella henselae and with different Bartonella henselae strains in domestic cats, J Clin Microbiol 1997; 35: 2120-2123

24. Higgins JA, Radulovic S, Jaworski DC, Azad AF, Acquisition of the cat scratch disease agent Bartonella henselae by cat fleas (Siphonaptera: Pulicidae)., J Med Entomol 1996; 33: 490-495

25. Jameson P, Greene C, Regnery R, et al. Prevalence of Bartonella henselae antibodies in pet cats throughout regions of North America, J Infect Dis 1995; 172: 1145-149

26. Kabeya H, Maruyama S, Irei M, Takahashi R, Yamashita M, Mikami T, Genomic variations among Bartonella henselae isolates derived from naturally infected cats, Vet Microbiol 2002; 89: 211-221

27. Kordick DL, Breitschwerdt EB, Relapsing bacteremia after blood transfusion of Bartonella henselae to cats, Am J Vet Res 1997; 58: 492-497

28. Kordick DL, Brown TT, Shin K, Breitschwerdt EB, Clinical and pathologic evaluation of chronic Bartonella henselae or Bartonella clarridgeiae infection in cats, J Clin Microbiol 1999; 37: 1536-1547

29. Kordick DL, Papich MG, Breitschwerdt EB, Efficacy of enrofloxacin or doxycycline for treatment of Bartonella henselae or Bartonella clarridgeiae infection in cats, Antimicrob Agent Chemother 1997; 41: 2448-2455

30. La VD, Clavel B, Lepetz S, Aboudharam G, Raoult D, Drancourt M, Molecular detection of Bartonella henselae DNA in the dental pulp of 800-year-old French cats, Clin Infect Dis 2004; 39: 1391-1394

31. Lappin MR, Griffin B, Burney D, Hawley J, Brewer MM, Jensen WA, Prevalence of Bartonella species, haemoplasma species, Ehrlichia species, Anaplasma phagocytophilum, and Neorickettsia risticii DNA in the blood of cats and their fleas in the United States, J Fel Med Surg 2006; 8: 85-90

32. Lappin MR, Kordick DL, Breitschwerdt EB, Bartonella spp. antibodies and DNA in aqueous humour of cats, J Fel Med Surg 2000; 2:61-8

33. LaScola B, Davoust B, Boni M, Raoult D, Lack of correlation between Bartonella DNA detection within fleas, serological results, and results of blood culture in a Bartonella-infected stray cat population, Clin Microbiol Infect 2002; 8: 345-351

34. Maruyama S, Kasten RW, Boulouis H-J, Gurfield NA, Katsube Y, Chomel BB, Genomic diversity of Bartonella henselae isolates from domestic cats from Japan, the USA and France by pulsed-field gel electrophoresis, Vet Microbiol 2000; 79: 337-349

35. Meininger GR, Nadasdy T, Hruban RH, Bollinger RC, Baughman KL, Hare JM, Chronic active myocarditis following acute Bartonella henselae infection (cat scratch disease), Am J Surg Pathol 2001; 25: 1211-1214

36. Nutter FB, Dubey JP, Levine JF, Breitschwerdt EB, Ford RB, Stoskopf MK, Seroprevalence of antibodies against Bartonella henselae and Toxoplasma gondii and fecal shedding of Cryptosporidium spp, Giardia spp, and Toxocara cati in feral and pet domestic cats, J Am Vet Med Assoc 2004; 225: 1394-1398

37. O'Reilly KL, Bauer RW, Freeland RL, et al. Acute clinical disease in cats following infection with a pathogenic strain of Bartonella henselae (LSU16), Infect Immun 1999; 67: 3066-3072

38. O'Reilly KL, Parr KA, Brown TP, Tedder-Ferguson B, Scholl DT, Passive antibody to Bartonella henselae protects against clinical disease following homologous challenge but does not prevent bacteremia in cats, Infect Immun 2001; 69: 1880-1882

39. Regnery RL, Rooney JA, Johnson AM, et al. Experimentally induced Bartonella henselae infections followed by challenge exposure and antimicrobial therapy in cats, Am J Vet Res 1996; 57: 1714-1719

40. Rolain J-M, Franc M, Davoust B, Raoult D, Molecular Detection of Bartonella quintana, B. koehlerae, B. henselae, B. clarridgeiae, Rickettsia felis, and Wolbachia pipientis in Cat Fleas in France, Emerg Infect Dis 2003; 9: 338-340

41. Ueno H, Hohdatsu T, Muramatsu Y, Koyama H, Morita C, Does coinfection of Bartonella henselae and FIV induce clinical disorders in cats?, Microbiol Immunol 1996; 40: 617-620

42. Werner JA, Kasten RW, Feng S, et al. Experimental infection of domestic cats with passaged genotype I Bartonella henselae, Vet Microbiol 2007; 122:290-7

43. Yamamoto K, Chomel BB, Kasten RW, et al. Homologous protection but lack of heterologous protection by various species and types of Bartonella in specific pathogen-free cats, Vet Immunol Immunopathol 1997; 65: 191-204

44. Yamamoto K, Chomel BB, Kasten RW, et al. Experimental infection of domestic cats with Bartonella koehlerae and comparison of protein and DNA profiles with those of other Bartonella species infecting felines, J Clin Microbiol 2002; 40: 466-474

45. Yamamoto K, Chomel BB, Kasten RW, et al. Infection and re-infection of domestic cats with various Bartonella species or types: B. henselae type I is protective against heterologous challenge with B. henselae type II, Vet Microbiol 2003; 92: 73-86

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