Human Babesia odocoilei and Bartonella spp. co-infections in the Americas

Background In recent years, Babesia and Bartonella species co-infections in patients with chronic, nonspecific illnesses have continued to challenge and change the collective medical understanding of "individual pathogen" vector-borne infectious disease dynamics, pathogenesis and epidemiology. The objective of this case series is to provide additional molecular documentation of Babesia odocoilei infection in humans in the Americas and to emphasize the potential for co-infection with a Bartonella species. Methods The development of improved and more sensitive molecular diagnostic techniques, as confirmatory methods to assess active infection, has provided increasing clarity to the healthcare community. Results Using a combination of different molecular diagnostic approaches, infection with Babesia odocoilei was confirmed in seven people suffering chronic non-specific symptoms, of whom six were co-infected with one or more Bartonella species. Conclusions We conclude that infection with Babesia odocoilei is more frequent than previously documented and can occur in association with co-infection with Bartonella spp.