Limited sharing of tick-borne hemoparasites between sympatric wild and domestic ungulates

Abstract

Tick-borne hemoparasites (TBHs) are a group of pathogens of concern in animal management because they are associated with a diversity of hosts, including both wild and domestic species. However, little is known about how frequently TBHs are shared across the wildlife-livestock interface in natural settings. Here, we compared the TBHs of wild Grant's gazelle (Nanger granti) and domestic sheep (Ovis aries) in a region of Kenya where these species extensively overlap. Blood samples collected from each species were screened for piroplasm and rickettsial TBHs by PCR-based amplification of 18S/16S ribosomal DNA, respectively. Overall, 99% of gazelle and 66% of sheep were positive for Babesia/Theileria, and 32% of gazelle and 47% sheep were positive for Anaplasma/Ehrlichia. Sequencing a subset of positive samples revealed infections of Theileria and Anaplasma. Sequences sorted into seven phylogenetically distinct genotypes-two Theileria, and five Anaplasma. With the exception of a putatively novel Anaplasma lineage from Grant's gazelle, these genotypes appeared to be divergent forms of previously described species, including T. ovis, A. ovis, A. bovis, and A. platys. Only one genotype, which clustered within the A. platys clade, contained sequences from both gazelle and sheep. This suggests that despite niche, habitat, and phylogenetic overlap, the majority of circulating tick-borne diseases may not be shared between these two focal species.

Keywords: Anaplasma; Gazelle; Hemoparasite; Parasite sharing; Sheep; Theileria; Tick-borne diseases.