Prevalence and Diversity of Piroplasms in Free-Ranging Ruminants in Nevada, USA

Wildlife may be infected with a high diversity of piroplasms and may serve as hosts or reservoirs for piroplasms of importance for domestic animals and public health. In the US, some piroplasms (e.g., Babesia spp. and Theileira cervi) have been associated with disease in native and exotic ungulates. Blood from 447 ruminants in Nevada were PCR tested for piroplasms, with 115 individuals from five species or subspecies found positive: 28/46 California bighorn sheep (Ovis canadensis californiana), 1/16 desert bighorn sheep (Ovis canadensis nelson), 70/255 mule deer (Odocoileus hemionus), 14/53 elk (Cervis canadensis nelsoni), and 2/55 pronghorn (Antilocapra americana). Six mountain goats (Oreamnos americanus) and four moose (Alces alces) were negative. Four piroplasm species were detected-Babesia duncani, Babesia sp. RD63, Babesia odocoilei, and Theileria cervi-like spp.-but three B. duncani strains were detected, giving seven unique species or strains. Babesia duncani, the most common piroplasm detected (83%), occurred in California and desert bighorn sheep, elk, and mule deer. Bighorn sheep were only infected with B. duncani, whereas mule deer and elk were each infected with three piroplasm species or strains. The single Theileria sp. and B. odocoilei detections were in pronghorn. Free-ranging ruminants in Nevada are infected with a high diversity of piroplasms, several of which are zoonotic or reported to cause disease in both wild and domestic ruminants.