Detection of Enzootic Babesiosis in Baboons (Papio cynocephalus) and Phylogenetic Evidence Supporting Synonymy of the GeneraEntopolypoidesandBabesia

Abstract

Blood smear evaluation of two baboons (Papio cynocephalus) experiencing acute hemolytic crises following experimental stem cell transplantation revealed numerous intraerythrocytic organisms typical of the genus Babesia. Both animals had received whole-blood transfusions from two baboon donors, one of which was subsequently found to display rare trophozoites of Entopolypoides macaci. An investigation was then undertaken to determine the prevalence of hematozoa in baboons held in our primate colony and to determine the relationship, if any, between the involved species. Analysis of thick and thin blood films from 65 healthy baboons (23 originating from our breeding facility, 26 originating from an out-of-state breeding facility, and 16 imported from Africa) for hematozoa revealed rare E. macaciparasites in 31%, with respective prevalences of 39, 35, and 12%. Phylogenetic analysis of nuclear small-subunit rRNA gene sequences amplified from peripheral blood of a baboon chronically infected withE. macaci demonstrated this parasite to be most closely related to Babesia microti (97.9% sequence similarity); sera from infected animals did not react in indirect fluorescent-antibody tests with Babesia microti antigen, however, suggesting that they represent different species. These results support an emerging view that the genusEntopolypoides Mayer 1933 is synonymous with that of the genus Babesia Starcovici 1893 and that the morphological variation noted among intracellular forms is a function of alteration in host immune status. The presence of an underrecognized, but highly enzootic, Babesia sp. in baboons may result in substantial, unanticipated impact on research programs. The similarity of this parasite to the known human pathogen B. microti may also pose risks to humans undergoing xenotransplantation, mandating effective screening of donor animals.

Detection of New Babesia microti-like Parasites in a Rhesus Monkey (Macaca mulatta) with a Suppressed Plasmodium cynomolgi Infection

“…Previously, a partial SSUrRNA sequence (PB-1; Figure 2A) was published of a new B. microti-like species that infected baboons. 2 The B. microti-like parasite SSUrRNA sequence from Ri12142 described here is clearly distinct from PB-1 (Figure 2A), revealing a new B. microti-like parasite that is capable of infecting a nonhuman primate.…”

“…1 Babesia-like parasites of the genus Entopolypoides macaci have been reported to infect nonhuman primates; based on phylogenetic analysis of small-subunit rRNA (SSUrRNA) sequences of this parasite and on serological and epidemiological data, it was suggested that the genus Entopolypoides is synonymous with that of Babesia. 2 In primate centers, natural infections with this parasite have been shown in baboons (Papio cynocephalus), 2 long-tailed macaques (Macaca fascicularis), 3 and rhesus macaques (Macaca mulatta), 4 providing animal models in species closely related to humans to study parasite-host relationships of this pathogen.…”

Babesia as a complication of immunosuppression following pig‐to‐baboon heart transplantation

“…As a result of this infection, which occurred at the Regional Primate Center in Washington State in the USA, an investigation was undertaken to determine the prevalence of hematozoa in baboons at that primate colony [16]. The incidence was 39% in colony-bred baboons, 35% in baboons that had been transferred from out-of-state breeding facilities, and 12% in baboons imported from Africa.…”

Isolation of a Human Erythrocyte-Adapted Substrain of Babesia rodhaini and Analysis of the Merozoite Surface Protein Gene Sequences

“…This result does not necessarily indicate that B. rodhaini is actually infectious and pathogenic to humans. However, precautions should be taken against this and other B. microti-like parasites that have increasingly been reported from a wide variety of wild animals [2,5,8,9,21,38] as a group of potentially zoonotic pathogens.…”

“…Experimentally, both B. rodhaini and B. microti have wide host ranges, and susceptible laboratory animals include mice, rats, hamsters, gerbils, and monkeys [10,23,25,27]. Natural infections by parasites closely related to B. microti or B. rodhaini have increasingly been reported in dogs [38], cats [8], lions [21], foxes [9], skunks [9], raccoons [2], and baboons [5]. Nonetheless, B. microti sensu stricto ("clade 1" in the reference [9]) is currently regarded as the sole etiologic agent of human babesiosis within the group of parasites.…”