Emerging rodent-associated Bartonella: a threat for human health?

Abstract

AbstractBackgroundSpecies of the genusBartonellaare facultative intracellular alphaproteobacteria with zoonotic potential.Bartonellainfections in humans range from mild with unspecific symptoms to life threatening, and can be transmitted via arthropod vectors or through direct contact with infected hosts, although the latter mode of transmission is rare. Among the small mammals that harbourBartonellaspp., rodents are the most speciose group and harbour the highest diversity of these parasites. Human–rodent interactions are not unlikely as many rodent species live in proximity to humans. However, a surprisingly low number of clinical cases of bartonellosis related to rodent-associatedBartonellaspp. have thus far been recorded in humans.MethodsThe main purpose of this review is to determine explanatory factors for this unexpected finding, by taking a closer look at published clinical cases of bartonellosis connected with rodent-associatedBartonellaspecies, some of which have been newly described in recent years. Thus, another focus of this review are these recently proposed species.ConclusionsWorldwide, only 24 cases of bartonellosis caused by rodent-associated bartonellae have been reported in humans. Possible reasons for this low number of cases in comparison to the high prevalences ofBartonellain small mammal species are (i) a lack of awareness amongst physicians ofBartonellainfections in humans in general, and especially those caused by rodent-associated bartonellae; and (ii) a frequent lack of the sophisticated equipment required for the confirmation ofBartonellainfections in laboratories that undertake routine diagnostic testing. As regards recently describedBartonellaspp., there are presently 14 rodent-associatedCandidatustaxa. In contrast to species which have been taxonomically classified, there is no official process for the review of proposedCandidatusspecies and their names before they are published. This had led to the use of malformed names that are not based on the International Code of Nomenclature of Prokaryotes. Researchers are thus encouraged to proposeCandidatusnames to the International Committee on Systematics of Prokaryotes for approval before publishing them, and only to propose new species ofBartonellawhen the relevant datasets allow them to be clearly differentiated from known species and subspecies.Graphical Abstract