Bacteria from the genus Bartonella are emerging blood-borne bacteria, capable of causing long-lasting infection in marine and terrestrial mammals, including humans. Bartonella are generally well adapted to their main host, causing persistent infection without clinical manifestation. However, these organisms may cause severe disease in natural or accidental hosts. In humans, Bartonella species have been detected from sick patients presented with diverse disease manifestations, including cat scratch disease, trench fever, bacillary angiomatosis, endocarditis, polyarthritis, or granulomatous inflammatory disease. However, with the advances in diagnostic methods, subclinical bloodstream infection in humans has been reported, with the potential for transmission through blood transfusion been recently investigated by our group. The objective of this study was to determine the risk factors associated with Bartonella species infection in asymptomatic blood donors presented at a major blood bank in Southeastern Brazil. Five hundred blood donors were randomly enrolled and tested for Bartonella species infection by specialized blood cultured coupled with high-sensitive PCR assays. Epidemiological questionnaires were designed to cover major potential risk factors, such as age, gender, ethnicity, contact with companion animals, livestock, or wild animals, bites from insects or animal, economical status, among other factors. Based on multivariate logistic regression, bloodstream infection with B. henselae or B. clarridgeiae was associated with cat contact (adjusted OR: 3.4, 95% CI: 1.1–9.6) or history of tick bite (adjusted OR: 3.7, 95% CI: 1.3–13.4). These risk factors should be considered during donor screening, as bacteremia by these Bartonella species may not be detected by traditional laboratory screening methods, and it may be transmitted by blood transfusion.
Bacteria from the genus Bartonella are capable of causing long-lasting infection. Despite the fact that these bacteria may cause several diseases such as cat scratch disease, trench fever, and infection of cardiac valves, which can be fatal, they may also cause asymptomatic infection in humans. Several blood-sucking arthropods have been suggested or confirmed as responsible for transmitting these bacteria, including sandflies, body lice, fleas, ticks, and keds. In this study, 500 asymptomatic human blood donors from Brazil were screened for infection with species of Bartonella by blood culture coupled with molecular detection and genetic sequencing, and risk factors associated with such infection were identified. In this population, contact with cats and history of tick bite were significantly associated with human infection by Bartonella species. Since laboratory screening of donated blood for the presence of Bartonella species is not generally performed by blood banks, these risk factors should be should be considered during donor screening in order to avoid transmission of Bartonella species by blood transfusion.