Bartonella species are blood-borne, re-emerging organisms, capable of causing prolonged infection with diverse disease manifestations, from asymptomatic bacteremia to chronic debilitating disease and death. This pathogen can survive for over a month in stored blood. However, its prevalence among blood donors is unknown, and screening of blood supplies for this pathogen is not routinely performed. We investigated Bartonella spp. prevalence in 500 blood donors from Campinas, Brazil, based on a cross-sectional design. Blood samples were inoculated into an enrichment liquid growth medium and sub-inoculated onto blood agar. Liquid culture samples and Gram-negative isolates were tested using a genus specific ITS PCR with amplicons sequenced for species identification. Bartonella henselae and Bartonella quintana antibodies were assayed by indirect immunofluorescence. B. henselae was isolated from six donors (1.2%). Sixteen donors (3.2%) were Bartonella-PCR positive after culture in liquid or on solid media, with 15 donors infected with B. henselae and one donor infected with Bartonella clarridgeiae. Antibodies against B. henselae or B. quintana were found in 16% and 32% of 500 blood donors, respectively. Serology was not associated with infection, with only three of 16 Bartonella-infected subjects seropositive for B. henselae or B. quintana. Bartonella DNA was present in the bloodstream of approximately one out of 30 donors from a major blood bank in South America. Negative serology does not rule out Bartonella spp. infection in healthy subjects. Using a combination of liquid and solid cultures, PCR, and DNA sequencing, this study documents for the first time that Bartonella spp. bacteremia occurs in asymptomatic blood donors. Our findings support further evaluation of Bartonella spp. transmission which can occur through blood transfusions.91 Breitschwerdt, E.B., Maggi, R.G., Chomel, B.B., Lappin, M.R., Bartonellosis: an emerging infectious disease of zoonotic importance to animals and human beings (2010) J Vet Emerg Crit Care, 20, pp. 8-30Chomel, B.B., Boulouis, H.J., Breitschwerdt, E.B., Kasten, R.W., Vayssier-Taussat, M., Ecological fitness and strategies of adaptation of Bartonella species to their hosts and vectors (2009) Vet Res, 40, p. 29Boulouis, H.J., Chang, C.C., Henn, J.B., Kasten, R.W., Chomel, B.B., Factors associated with the rapid emergence of zoonotic Bartonella infections (2005) Vet Res, 36, pp. 383-410Maggi, R.G., Mozayeni, B.R., Pultorak, E.L., Hegarty, B.C., Bradley, J.M., Bartonella spp. bacteremia and rheumatic symptoms in patients from Lyme disease-endemic region (2012) Emerg Infect Dis, 18, pp. 783-791Breitschwerdt, E.B., Maggi, R.G., Lantos, P.M., Woods, C.W., Hegarty, B.C., Bartonella vinsonii subsp. berkhoffii and Bartonella henselae bacteremia in a father and daughter with neurological disease (2010) Parasit Vectors, 3, p. 29Garcia-Caceres, U., Garcia, F.U., Bartonellosis. An immunodepressive disease and the life of Daniel Alcides Carrion (1991) Am J Clin Pathol, 95, pp. S58-66Pitassi, L.H., Cintra, M.L., Ferreira, M.R., Magalhaes, R.F., Velho, P.E., Blood cell findings resembling Bartonella spp (2010) Ultrastruct Pathol, 34, pp. 2-6Maggi, R.G., Mascarelli, P.E., Pultorak, E.L., Hegarty, B.C., Bradley, J.M., Bartonella spp. bacteremia in high-risk immunocompetent patients (2011) Diagn Microbiol Infect Dis, 71, pp. 430-437Harms, A., Dehio, C., Intruders below the radar: molecular pathogenesis of Bartonella spp (2012) Clin Microbiol Rev, 25, pp. 42-78Pulliainen, A.T., Dehio, C., Persistence of Bartonella spp. stealth pathogens: from subclinical infections to vasoproliferative tumor formation (2012) FEMS Microbiol Rev, 36, pp. 563-599Duncan, A.W., Maggi, R.G., Breitschwerdt, E.B., 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 (2007) J Microbiol Methods, 69, pp. 273-281Magalhaes, R.F., Pitassi, L.H., Salvadego, M., de Moraes, A.M., Barjas-Castro, M.L., Bartonella henselae survives after the storage period of red blood cell units: is it transmissible by transfusion? (2008) Transfus Med, 18, pp. 287-291Pitassi, L.H., Magalhaes, R.F., Barjas-Castro, M.L., de Paula, E.V., Ferreira, M.R., Bartonella henselae infects human erythrocytes (2007) Ultrastruct Pathol, 31, pp. 369-372Kordick, D.L., Brown, T.T., Shin, K., Breitschwerdt, E.B., Clinical and pathologic evaluation of chronic Bartonella henselae or Bartonella clarridgeiae infection in cats (1999) J Clin Microbiol, 37, pp. 1536-1547Oliveira, A.M., Maggi, R.G., Woods, C.W., Breitschwerdt, E.B., Suspected needle stick transmission of Bartonella vinsonii subspecies berkhoffii to a veterinarian (2010) J Vet Intern Med, 24, pp. 1229-1232Lin, J.W., Chen, C.M., Chang, C.C., Unknown fever and back pain caused by Bartonella henselae in a veterinarian after a needle puncture: a case report and literature review (2011) Vector Borne Zoonotic Dis, 11, pp. 589-591Arvand, M., Schad, S.G., Isolation of Bartonella henselae DNA from the peripheral blood of a patient with cat scratch disease up to 4 months after the cat scratch injury (2006) J Clin Microbiol, 44, pp. 2288-2290Lantos, P.M., Maggi, R.G., Ferguson, B., Varkey, J., Park, L.P., Detection of Bartonella species in the blood of veterinarians and veterinary technicians: a newly recognized occupational hazard? (2014) Vector Borne Zoonotic Dis, 14, pp. 563-570Chamberlin, J., Laughlin, L.W., Romero, S., Solorzano, N., Gordon, S., Epidemiology of endemic Bartonella bacilliformis: a prospective cohort study in a Peruvian mountain valley community (2002) J Infect Dis, 186, pp. 983-990Foucault, C., Barrau, K., Brouqui, P., Raoult, D., Bartonella quintana bacteremia among homeless people (2002) Clin Infect Dis, 35, pp. 684-689(2012) Standards for blood banks and transfusion services(2010) Guide to the preparation, use and quality assurance of blood componentsMaggi, R.G., Duncan, A.W., Breitschwerdt, E.B., Novel chemically modified liquid medium that will support the growth of seven Bartonella species (2005) J Clin Microbiol, 43, pp. 2651-2655Drummond, M.R., Pitassi, L.H., Lania, B.G., Dos Santos, S.R., Gilioli, R., Detection of Bartonella henselae in defibrinated sheep blood used for culture media supplementation (2011) Braz J Microbiol, 42, pp. 430-432Cadenas, M.B., Maggi, R.G., Diniz, P.P., Breitschwerdt, K.T., Sontakke, S., Identification of bacteria from clinical samples using Bartonella alpha-Proteobacteria growth medium (2007) J Microbiol Methods, 71, pp. 147-155Diniz, P.P., Maggi, R.G., Schwartz, D.S., Cadenas, M.B., Bradley, J.M., Canine bartonellosis: serological and molecular prevalence in Brazil and evidence of co-infection with Bartonella henselae and Bartonella vinsonii subsp. berkhoffii (2007) Vet Res, 38, pp. 697-710Norman, A.F., Regnery, R., Jameson, P., Greene, C., Krause, D.C., Differentiation of Bartonella-like isolates at the species level by PCR-restriction fragment length polymorphism in the citrate synthase gene (1995) J Clin Microbiol, 33, pp. 1797-1803Varanat, M., Maggi, R.G., Linder, K.E., Breitschwerdt, E.B., Molecular prevalence of Bartonella, Babesia, and hemotropic Mycoplasma sp. in dogs with splenic disease (2011) J Vet Intern Med, 25, pp. 1284-1291McGill, S., Wesslen, L., Hjelm, E., Holmberg, M., Auvinen, M.K., Bartonella spp. seroprevalence in healthy Swedish blood donors (2005) Scand J Infect Dis, 37, pp. 723-730Zarkovic, A., McMurray, C., Deva, N., Ghosh, S., Whitley, D., Seropositivity rates for Bartonella henselae, Toxocara canis and Toxoplasma gondii in New Zealand blood donors (2007) Clin Experiment Ophthalmol, 35, pp. 131-134Mosepele, M., Mazo, D., Cohn, J., Bartonella infection in immunocompromised hosts: immunology of vascular infection and vasoproliferation (2012) Clin Dev Immunol, 2012, p. 612809Guptill, L., Slater, L., Wu, C.C., Lin, T.L., Glickman, L.T., Experimental infection of young specific pathogen-free cats with Bartonella henselae (1997) J Infect Dis, 176, pp. 206-216Velho, P.E., Pimentel, V., Del Negro, G.M., Okay, T.S., Diniz, P.P., Severe anemia, panserositis, and cryptogenic hepatitis in an HIV patient infected with Bartonella henselae (2007) Ultrastruct Pathol, 31, pp. 373-377Lamas, C., Curi, A., Boia, M., Lemos, E., Human bartonellosis: seroepidemiological and clinical features with an emphasis on data from Brazil—a review (2008) Mem Inst Oswaldo Cruz, 103, pp. 221-235Perez, V.C., Diniz, P.P., Pultorak, E.L., Maggi, R.G., Breitschwerdt, E.B., (2013) An unmatched case controlled study of clinicopathologic abnormalities in dogs with Bartonella infectionPerez, C., Hummel, J.B., Keene, B.W., Maggi, R.G., Diniz, P.P., Successful treatment of Bartonella henselae endocarditis in a cat (2010) J Feline Med Surg, 12, pp. 483-486Diniz, P.P., Wood, M., Maggi, R.G., Sontakke, S., Stepnik, M., Co-isolation of Bartonella henselae and Bartonella vinsonii subsp. berkhoffii from blood, joint and subcutaneous seroma fluids from two naturally infected dogs (2009) Vet Microbiol, 138, pp. 368-372Ajello, G.W., Feeley, J.C., Hayes, P.S., Reingold, A.L., Bolan, G., Trans-Isolate medium: A new medium for primary culturing and transport of Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae (1984) Journal of Clinical Microbiology, 20, pp. 55-58Pultorak, E.L., Maggi, R.G., Mascarelli, P.E., Breitschwerdt, E.B., Serial testing from a 3-day collection period by use of the Bartonella Alphaproteobacteria growth medium platform may enhance the sensitivity of Bartonella species detection in bacteremic human patients (2013) J Clin Microbiol, 51, pp. 1673-1677da Costa, P.S., Brigatte, M.E., Greco, D.B., Antibodies to Rickettsia rickettsii, Rickettsia typhi, Coxiella burnetii, Bartonella henselae, Bartonella quintana, and Ehrlichia chaffeensis among healthy population in Minas Gerais, Brazil (2005) Mem Inst Oswaldo Cruz, 100, pp. 853-859Perez, C., Maggi, R.G., Diniz, P.P., Breitschwerdt, E.B., Molecular and serological diagnosis of Bartonella infection in 61 dogs from the United States (2011) J Vet Intern Med, 25, pp. 805-810Vermeulen, M.J., Verbakel, H., Notermans, D.W., Reimerink, J.H.J., Peeters, M.F., Evaluation of sensitivity, specificity and cross-reactivity in Bartonella henselae serology (2010) Journal of Medical Microbiology, 59, pp. 743-745Wolf, L.A., Cherry, N.A., Maggi, R.G., Breitschwerdt, E.B., In Pursuit of a Stealth Pathogen: Laboratory Diagnosis of Bartonellosis (2014) Clinical Microbiology Newsletter, 36, pp. 33-39Wardrop, K.J., Reine, N., Birkenheuer, A., Hale, A., Hohenhaus, A., Canine and feline blood donor screening for infectious disease (2005) J Vet Intern Med, 19, pp. 135-142Pennisi, M.G., Marsilio, F., Hartmann, K., Lloret, A., Addie, D., Bartonella Species Infection in Cats: ABCD guidelines on prevention and management (2013) Journal of Feline Medicine and Surgery, 15, pp. 563-569