Original Article

Seropositivity of Bartonella henselae in Risky Human Population, Cats and Dogs


  • Neriman Aydın
  • Berna Korkmazgil
  • Şükrü Kırkan
  • Murat Telli
  • Mete Eyigör
  • Atiye Meltem Aksoy
  • Uğur Parın
  • Serten Tekbıyık

Received Date: 01.03.2017 Accepted Date: 11.02.2018 Meandros Med Dent J 2019;20(1):51-56


Bartonella species cause several diseases in humans such as cat scratch disease, bacillary angiomatosis, peliosis hepatis, endocarditis, Carrion disease and trench fever. There have been cat scratch disease and bacillary angiomatosis cases reports in Turkey. The aim of this study is to determine the seropositivity against Bartonella henselae in cat/dog owners who are in the risk group, cats and dogs in Western Aegean region, Turkey.

Materials and Methods:

In this study, B. henselae immunoglobulin (Ig) G positivity was investigated in a total of 281 samples including a total of 131 people, 34 of whom are pet cat/dog owners and 97 of whom are stray cat/dog owners; as well as a total of 105 cats, of which 57 pet cats, 48 shelter cats, and 45 pet dogs. Sera tested for the presence of antibodies against B. henselae IgG using immunofluorescence assay with two commercial kits.


B. henselae seropositivity of pet owners was significantly higher than the stray cat/dog owners (26.5% vs 6.8%). B. henselae IgG was found positive in 36.2% of total cats, 22.8% of pet cats, 52.1% of shelter cats. B. henselae seropositivity was found statistically higher in shelter cats than pet cats. No positivity was detected in the samples taken from the dogs.


It is concluded that being pet owner at home poses a risk for B. henselae. For the differential diagnosis, especially in patients in close contact with cats, B. henselae infection should be considered.

Keywords: Bartonella henselae, risky human, cat, dog, seropositivity


Bartonella genus received its name in 1909 from Alberto L. Barton who was working with and who also identified Bartonella bacilliformis, the cause of Carrion disease. B. bacilliformis has been accepted as the only member of this genus until a recent classification. Bartonella genus, which had previously been in Rickettsiales order, Rickettsiaceae family, was included in Protobacteria class, Alphaproteobacteria sub-group, Bartonellaceae family in 1993 (1). Bartonella species have adapted to many vertebrate hosts; humans, carnivores, rodents, ruminants, marine mammals, primates and bats. This group of bacteria has a high genetic diversity and adapt to changes in the ecological conditions. In recent years, new isolated species have been continually added to Bartonella genus (2). It is reported that seventeen of these species and 3 subspecies are associated with human disease; ([2] http://www.bacterio.net/bartonella.htm) (3-8).

All Bartonella species have specific mammalian hosts, in which they cause a long-lasting infection known as intraerythrocytic bacteraemia. Domestic cats are the principle reservoir for B. henselae, B. clarridgeiae and B. koehlerae (5,9,10). Among them, B. henselae is the most important zoonotic species to cause human disease.

B. henselae is continuously expanding and includes cat scratch disease (CSD), bacillary angiomatosis and peliosis hepatis, endocarditis, myocarditis, prolonged bacteremia and fever, ocular manifestations, encephalopathy, aseptic meningitis, acute hemiplegia, dementia, acute psychiatric symptoms, hepatosplenic abscesses, asymptomatic bacteremia, osteomyelitis, erythema nodosum, other skin lesions in human (11). Domestic cats represent the natural reservoir for the bacteria (12). Infected cats develop relapsing bacteremia, which may persist for up to two years (13,14). Cat flea (Ctenocephalides felis) transmits the bacteria from cats to new hosts. Although some of these animals may be bacteremic over a period of more than one year, cats have relatively asymptomatic infection (13). Transmission from cats to human mainly occurs by cat scratch or bite or possibly by flea bite.

According to the studies in humans, B. henselae immunoglobulin (Ig) G positivity is 8.7-19.8% in healthy children and adolescents, 10.3-28.9% in risky group humans, 11-16% in human immunodeficiency virus infected patient and 3.3-6% in blood donors (15-24). In Turkey, related to Bartonella, there are case reports of CSD and bacillar angiomatosis, and seroprevalence studies conducted in blood donors, cats and dogs samples (23,25-30). The objective of this study is to determine the prevalence of serum antibodies against B. henselae which has gained importance in recent years, in risky human, cats and dogs in Western Aegean region, Turkey.

Materials and Methods

This research was conducted by a team of researchers of Aydın Adnan Menderes University Veterinary and Medicine Faculties, Aydın, Turkey in blood samples collected from adults who are cat/dog owners, pet cats/dogs and shelter cats in Aydın and İzmir province. The permissions of both human and animal ethics committees were taken.

In this study, B.henselae IgG positivity was investigated in a total of 281 samples including a total of 131 people, 34 of whom are pet cat/dog owners and 97 of whom are stray cat/dog owners; as well as a total of 105 cats, of which 57 pet cats, 48 shelter cats, and 45 pet dogs. Bartonella henselae IgG antibodies were investigated in the all sera with indirect immunofluorescence antibody (IFA) method by using two commercial kits which were double compartmented B. henselea & quintana IFA IgG (Vircell, Granada, Spain) kits containing B. henselea cepa Houston-1 (ATCC 49882) and B. quintana (CIP 107 027 N) grown on Vero cells; and compartmented Bartonella IFA IgG (Focus, California, U.S.A) kits containing B. henselea and B. quintana bacteria produced in yolk sac cells. Antibodies were investigated in cat samples by using fluorescein labeled goat anti-feline IgG as conjugate, and in dog samples by using fluorescein labeled rabbit anti-canine IgG (Santa Cruz Biotechnology, Texas, USA).

All sera samples were tested with B. henselae & quintana IFA IgG (Vircell) kits in 1/32 and 1/64 dilutions. The samples which were positive in 1/64 titers were consecutively tested with both kits in 1:64, 1:128, 1:256, 1:512 dilutions, and positive titrations were determined. Slides were viewed at a final magnification of 400× on fluorescent microscope by two different assigned researchers. Fluorescent intensity was graded as +1-+4, and the samples with fluorescence ≥+2 were considered as positive. Positive and negative controls were used for each study.


B. henselae IgG positivity was on average 11.5% for risk group humans (cat/dog owners) (Table 1). B. henselae seroprevalence of pet owners was significantly higher than the stray cat/dog owners (26.5% vs 6.8%). B. henselae seropositivity was found in 36.2% of total cats, 22.8% of pet cats and 52.1% of shelter cats (Table 2). B. henselae seropositivity was found statistically higher in shelter cats than pet cats. The positivity in cats in 1/64 dilution was 20.0%, in 1/128 dilution was 13.3%, and in 1/256 dilution was 2.8% (Table 3). All dog samples were found negative for B. henselae IgG.

The seropositivity of B. quintana IgG in some samples were found lower than B. henselae IgG titers and this was considered as cross reactivity (31).


In this study, B. henselae seropositivity was determined in risk group human and both pet and stray cats in Western Aegean region of Turkey. B. henselae IgG positivity was 11.5% for risk group human (cat/dog owners), 26.5% for pet cat/dog owners and 6.2% for stray cat owners (Table 1). It was found that owning pet cats increases seropositivity significantly. Having a pet cat poses a higher risk to B. henselae infections than having a stray cat. In Turkey, related to Bartonella, there are case reports of CSD and bacillary angiomatosis (25-28). In a study conducted in Aydin province, Turkey, Bartonella seroprevalence in blood donors was found 3,3% (24), and another study was conducted in Denizli, a neighbour city of Aydın, with blood donors B. henselae seroprevalence was found as 6.0% (23). The presence of similar seroprevalence rates on the two adjacent provinces suggests that B henselae infections are undergoing in this area. Bartonella spp seropositivity has been reported to be between 1.2% and 19.6% in healthy individuals and between 2.6% and 65% at different risk groups in various countries (32-35).

B. henselae seropositivity was found positive in 36.2% of total cats, 22.8% of pet cats and 52.1% of shelter cats. The seropositivity was lower in stray cat owners compared to pet cat owners. This result suggests that the seropositivity in humans may be associated with close contact to cats. Domesticated cats are main reservoirs for B. henselae (9,36,37). Seroprevalence in cats varies according to geographical regions and climatic characteristics (18,38). B. henselae seroprevalence of domestic cats has been reported between 5 and 81% (36,38,39). In a similar study conducted in Ankara-Turkey, seroprevalence in cats was found as 18.8% (29). Seropositivity of B. henselae in cats is observed to be high in temperate and humid regions and low in cold and arid regions. This is due to the increased proliferation of cat fleas in temperate climates, so that in humid, temperate climates, cat fleas produce intensive infestation in the cats, resulting in the rise of B. henselae prevalence (36,38-40). Seropositivity against Bartonella species in humans is an expected outcome due to warm and mild climate of Aydın and İzmir provinces, where this study is conducted.

In dogs, Bartonella species may lead to clinical disorders such as endocarditis, bacillary angiomatosis, granulomatous hepatitis, lymphadenitis and granulomatous rhinitis (41-43). B. vinsonii subsp. berkhoffii is the first Bartonella type isolated from dogs, the isolation of B.henselae, B. clarridgeiae and other species has showed a significant increase (42). Although the role of dogs for transmission of Bartonella species is unclear, they are important due to the possibility that they may become reservoirs. In two studies conducted in the US, B. henselea seropositivity have been reported in 10.1% of healthy dogs and 27.2-32% of the ill dogs (44,45). In another study conducted in Spain, B. henselea seropositivity was found as 16.8%, whereas B. vinsonii subsp. berkhoffii was found as 1.1% (46). In our study, all pet dogs samples were negative in B. henselae IgG. This result may be related to the fact that the study was conducted in pet dogs, and in order to suggest that B. henselae is not present in dogs in our region, it is necessary to conduct a research on both stray and shelter dogs. There has been no study on B. henselae isolation in neither pet nor stray/shelter dogs in Turkey. However, in a study all species which has been isolated was B. vinsonii subsp. berkhoffii and B. vinsonii subsp. berkhoffii IgG seroprevalence has been reported as 3% in stray dogs and 12% in rural dogs (30).

Study Limitation

The limitations of this study include several topics since it was not possible to distinguish individuals as stray cat/dog owners. Moreover, since the maintainance of contact, sampling, disease anamnesis and screening of stray cats and dogs were difficult, the use of these animal samples were limited in this research. The recent Bartonella infection could not be diagnosed because Bartonella IgM did not be investigated in the sera samples.


In humans, CSD is usually clinically suspected and diagnosed by the determination of antibodies against B. henselae or the bacterial DNA from the tissue kept. Since it is difficult to culture Bartonella species from human samples, serological diagnosis is the first step to confirm the preliminary diagnosis. Many tests have been developed for the serological diagnosis with varying in sensitivity and specificity (IFA, enzim immünoassay, immunoblot). Indirect IFA is one of the most commonly used methods of serological tests. IgG titer is 1/512 and above in CSD. However, low antibody titers, such as 1/64 and 1/128 titers, can be found in both patients and healthy controls. As low antibody titers can be found at the beginning or the end of disease, they also can only be related to the exposure to the causative agent (18,47). Two different commercial kits were used in this study. First, all sera were run in 1/64 dilution with B. henselae & quintana IFA IgG (Vircell) kit. The sera which were subsequently positive were also studied with the Bartonella IFA IgG (Focus) kit. The difference between these two kits is that the wells on the slides of the screening kits contain B. henselae, cepa Houston-1 (ATCC49882) and B.quintana (N CIP 1070271) bacteria produced in Vero cells, while the other kit contains bacteria-infected Vero cells. As the production methods of the kits differ, there are also differences in terms of cost. Direct and dilution results were found to be compatible between the kits used in this study. Regnery and colleagues used Vero cells infected with B. henselae as antigens in CSD serology (48). Many researchers have used B. henseale and infected Vero cells as IFA antigens based on the work of Regnery and colleagues (20,21,49,50)

Bartonella species cause many different types of clinical findings in human and animals. Especially the role of cats spreading CSD to people by being reservoirs is well known. Isolation of Bartonella species, which are increasingly important zoonotics, in cats and dogs in a geographical region may be a sign of humans in that having the disease, and therefore epidemiological studies in human and animals are required. This study is the first report of the B. henselae positivity seroprositivity in cats, dogs and pet owners in Western Aegean region of Turkey. We found out that being pet owner at home poses a risk for B.henselae. Especially in patients in close contact with cats, B. henselae infection should be considered for the differential diagnosis.


Ethics Committee Approval: HEK/2008/006, EK/2008/00224.

Informed Consent: Written informed consent was obtained from all participants.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Surgical and Medical Practices: Not made Concept: N.A., B.K., S.K., M.T., M.E., Design: N.A., M.E., S. K., B.K., M.T., Data Collection or Processing: S.K., U.P., S.T., B.K., M.E., A.M.A., Analysis or Interpretation: N.A., B.K., S.K., M.E., A.M.A., M.T., Literature Search: N.A., B.K., M.E., S.K., A.M.A., Writing: N.A., B.K., M.E., S.K.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: TPF-08012 The project was supported by the Scientific Research Projects Unit of Adnan Menderes University.


  1. Welch DF. Bartonellaceae. In: Garrity GM, Brenner DJ, Krieg NR, Staley JT, editors. Bergey’s Manual of Systematic Bacteriology. 2nd ed. New York: Springer, 2005: 362-70.
  2. Kosoy M, Hayman DTS, Chan KS. Bartonella bacteria in nature: Where does population variability end and a species start? Infect Genet Evol 2012; 12: 894-904.
  3. Chomel BB, Molia S, Kasten RW, Borgo GM, Stuckey MJ, Maruyama S, et al. Isolation of Bartonella henselae and Two New Bartonella Subspecies, Bartonella koehlerae  Subspecies boulouisii subsp. nov. and Bartonella koehlerae Subspecies bothieri subsp. nov. from Free-Ranging Californian Mountain Lions and Bobcats PloS One 2016; 11: 1-21.
  4. http://www.bacterio.net/bartonella.html: List of procaryotic names with standing in nomenclalature.
  5. Jacomo V, Kelly PJ, Raoult D. Natural history of Bartonella infections (an exception to Koch’s postulate). Clin Diagn Lab Immunol 2002; 9: 8-18.
  6. Kosoy M, Murray M, Gilmore RD Jr, Bai Y, Gage KL. Bartonella strains from ground squirrels are identical to Bartonella washoensis isolated from a human patient. J Clin Microbiol 2003; 41: 645-50.
  7. Kosoy M, Morway C, Sheff KW, Bai Y, Colborn J, Chalcraft L, et al. Bartonella tamiae sp. nov., a newly recognized pathogen isolated from three human patients from Thailand. J Clin Microbiol 2008; 46: 772-5.
  8. Maggi RG, Kosoy M, Mintzer M, Breitschwerdt EB. Isolation of Candidatus Bartonella melophagi from human blood. Emerg Infect Dis 2009; 15: 66-8.
  9. Koehler JE, Glase CA, Tappero JT. Rochalimaea henselae infection: A new zoonosis with the domestic cat as reservoir. JAMA 1994; 271: 531-5.
  10. Chomel BB, Kasten RW. Bartonellosis, an increasingly recognized zoonosis. J Appl Microbiol 2010; 109: 743-50.
  11. Lamas C, Curi A, Boia MN, Lemos ER. Human Bartonellosis: Seroepidemiological and clinical features with an emphasis on data from Brazil-A Review. Mem Inst Oswaldo Cruz 2008; 103: 221-35.
  12. Regnery R, Martin M, Olson J. Naturally occurring ‘‘Rochalimaea henselae’’ infection in domestic cat. Lancet 1992; 340: 557-8.
  13. Breitschwerdt EB, Kordick DL. Bartonella infection in animals: Carriership, reservoir potential, pathogenicity, and zoonotic potential for human infection. Clin Microbiol Rev 2000; 13: 428-38.
  14. 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: 211-21.
  15. Aydın N, Bülbül R, Telli M, Gültekin B. Seroprevalence of Bartonella henselae and Bartonella quintana in Blood Donors in Aydin Province, Turkey. Mikrobiyol Bul 2014; 48: 477-83.
  16. Yousif A, Farid I, Baig B, Creek J, Olson P, Wallace M. Prevalence of Bartonella henselae antibodies among human immunodeficiency virus-infected patients from Bahrain. Clin Infect Dis 1996; 23: 398-9.
  17. Blanco Ramos JR, Oteo Revuelta JA, Martínez de Artola V, Ramalle Gómara E, García Pineda A, Ibarra Cucalón V. Seroepidemiology of Bartonella henselae infection in a risk group. Rev Clin Esp 1998; 198: 805-9.
  18. Sander A, Berner R, Ruess M. Serodiagnosis of cat scratch disease: response to Bartonella henselae in children and a review of diagnostic methods. Eur J Clin Microbiol Infect Dis 2001; 20: 392-401.
  19. Kikuchi E, Maruyama S, Sakai T, Tanaka S, Yamaguchi F, Hagiwara T, et al. Serological investigation of Bartonella henselae infections in clinically cat-scratch disease-suspected patients, patients with cardiovascular diseases, and healthy veterinary students in Japan. Microbiol Immunol 2002; 46: 313-6.
  20. Tea A, Alexiou-Daniel S, Arvanitidou M, Diza E, Antoniadis A. Occurrence of Bartonella henselae and Bartonella quintana in a healthy Greek population. Am J Trop Med Hyg 2003; 68: 554-6.
  21. Ferrés GM, Abarca VK, Prado DP, Montecinos PL, Navarrete CM, Vial CPA. Prevalence of Bartonella henselae antibodies in Chilean children, adolescents and veterinary workers. Rev Med Chil 2006; 134: 863-7.
  22. Pons I, Sanfeliu I, Cardenosa N, Nogueras MM, Font B, Segura F. Serological evidence of Bartonella henselae infection in healthy people in Catalonia, Spain. Epidemiol Infect 2008; 136: 1712-6.
  23. Yilmaz C, Ergin C, Kaleli I. Investigation of Bartonella henselae seroprevalence and related risk factors in blood donors admitted to Pamukkale University Blood Center. Mikrobiyol Bul 2009; 43: 391-401.
  24. Oray M, Önal S, Koç Akbay A, Tuğal Tutkun İ. Diverse clinical signs of ocular involvement in cat scratch disease.  Turk J Ophthalmol 2017; 47: 9-17.
  25. Karakas M, Baba M, Aksungur VL, Homan S, Memisoglu HR, Uguz A. Bacillary angiomatosis on a region of burned skin in a immunocompetent patient. Br J Dermatol 2000; 143: 609-11.
  26. Kayaselcuk F, Ceken I, Bircan S, Tuncer I. Bacillary angiomatosis of the scalp in a human immunodeficiency virus-negative patient. Eur Acad Dermatol Venerol 2000; 16: 612-4.
  27. Aydogan I, Parlak AH, Alper M, Aksoy AA. Bacillary angiomatosis in an HIV seronegative patient. TURKDERM 2004; 38: 71-4.
  28. Kara B, Ucan S, Basim B, Ercin C, Arisoy ES. Hepatosplenic cat scratch disease: a case report. Cocuk Dergisi 2004; 4: 58-60.
  29. Celebi B, Kilic S, Aydin N, Tarhan G, Carhan A, Babur C. Investigation of Bartonella henselae in Cats in Ankara, Turkey. Zoonoses Public Health 2009; 56: 169-75.
  30. Celebi B, Taylan OA, Kilic S, Akca A, Koenhemsi L, Pasa S, et al. Seroprevalence of Bartonella vinsonii subsp. berkhoffii in urban and rural dogs in Turkey. J Vet Med Sci 2010; 72: 1491-4.
  31. Sander A, Posselt M, Oberle K, Bredt W. Seroprevalence of antibodies to Bartonella henselae in patients with cat scratch disease and in healthy controls: evaluation and comparison of two commercial serological tests. Clin Infect Dis 2001; 33: 1852-8.
  32. McGill S, Wesslén L, Hjelm E, Holmberg M, Auvinen MK, Berggren K, et al. Bartonella spp. seroprevalence in healthy Swedish blood donors. Scand J Infect Dis 2005; 37: 723-30.
  33. Sun J, Fu G, Lin J, Song X, Lu L, Liu Q. Seroprevalence of Bartonella in Eastern China and analysis of risk factors. BMC Infect Dis 2010; 10: 121.
  34. Juncker-Voss M, Prosl H, Lussy H, Enzenberg U, Auer H, Lassnig H, et al. Screening for antibodies against zoonotic agents among employees of the Zoological Garden of Vienna, Schönbrunn, Austria. Berl Munch Tierarztl Wochenschr 2004; 117: 404-9.
  35. Zhang Y, Zhang ZL, Yin JY, Lv J, Yu HL, Liang CW, et al. [Sero-epidemiological investigation on Rickettsia typhi, Bartonella henselae and Orientia tsutsugamushi in farmers from rural areas of Tianjin, 2007 - 2009]. Zhonghua Liu Xing Bing Xue Za Zhi 2011; 32: 256-9.
  36. Chomel BB, Abbott RC, Kasten RW, Floyd-Hawkins KA, Kass PH, Glaser CA, et al. Bartonella henselae prevalence in domestic cats in California: Risk factors and association between bacteremia and antibody titers. J Clin Microbiol 1995; 33: 2445-50.
  37. Joseph AK, Wood CW, Robson JM, Paul SL, Morris AJ. Bartonella henselae bacteraemia in domestic cats from Auckland. N Z Vet J 1997; 45: 185-7.
  38. Jameson P, Greene C, Regnery R, Dryden M, Marks A, Brown J, et al. Prevalence of Bartonella henselae Antibodies in pet cats throughout regions of North America. J Infect Dis 1995; 172: 1145-9.
  39. Chomel BB, Boulouis HJ, Petersen H, Kasten RW, Yamamoto K, Chang CC, et al. Prevalence of Bartonella infection in domestic cats in Denmark. Vet Res 2002; 33: 205-13.
  40. Maruyama S, Nakamura Y, Kabeya H, Tanaka S, Sakai T, Katsube Y. Prevalence of Bartonella henselae, Bartonella clarridgeiae and the 16S rRNA gene types of Bartonella henselae among pet cats in Japan. J Vet Med Sci 2000; 62: 273-9.
  41. Kitchell BE, Fan TM, Kordick D, Breitschwerdt EB, Wollenberg G, Lichtensteiger CA. Peliosis hepatis in a dog infected with Bartonella henselae. J Am Vet Med Assoc 2000; 216: 519-23.
  42. Mexas AM, Hancock SI, Breitschwerdt EB. Bartonella henselae and Bartonella elizabethae as potential canine pathogens. J Clin Microbiol 2002; 40: 4670-4.
  43. Gillespie TN, Washabau RJ, Goldschmidt MH, Cullen JM, Rogala AR, Breitschwerdt EB. Detection of Bartonella henselae and Bartonella clarridgeiae DNA in hepatic specimens from two dogs with hepatic disease. J Am Vet Med Assoc 2003; 222: 47-51.
  44. Solano-Gallego L, Bradley J, Hegarty B, Sigmon B, Breitschwerdt E. Bartonella henselae IgG antibodies are prevalent in dogs from southeastern USA. Vet Res 2004; 35: 585-95.
  45. Duncan AW, Maggi RG, Breitschwerdt EB. A combined approach for the enhanced detection and isolation of Bartonella species in dog blood samples: Pre-enrichment liquid culture followed by PCR and subculture onto agar plates. J Microbiol Methods 2007; 69: 273-81.
  46. Solano-Gallego L, Llull J, Osso M, Hegarty B, Breitschwerdt E. A serological study of exposure to arthropod-borne pathogens in dogs from northeastern Spain. Vet Res 2006; 37: 231-44.
  47. Dalton MJ, Robinson LE, Cooper J, Regnery RL, Olson JG, Child JE. Use of Bartonella antigens for serologic diagnosis of cat-scratch disease at a national referral center. Arch Intern Med 1995; 155: 1670-6.
  48. Sander A, Posselt M, Oberle K, Bredt W. Seroprevalence of antibodies to Bartonella henselae in patients with cat scratch disease and in healthy controls: evaluation and comparison of two commercial serological tests. Clin Infect Dis 2001; 33: 1852-8.
  49. Yoshida H, Kusaba N, Ornachi K, Miyazaki N, Yarnawaki M, Tsuji Y, et al. Serological Study of Bartonella henselae in Cat Scratch Disease in Japan. Microbiol Immunol 1996; 40: 671-3.
  50. Del Prete R, Fumarola D, Fumarola L, Basile V, Mosca A, Miragliotta G. Prevalence of antibodies to Bartonella henselae in patients with suspected cat scratch disease (CSD) in Italy. Eur J Epidemiol 1999; 15: 583-7.