THE ISOLATION AND PARTIAL CHARACTERIZATION OF A BABESIA SP FROM DESERT BIGHORN SHEEP (OVIS-CANADENSIS-NELSONI)

A novel Babesia parasite of desert bighorn sheep was isolated. Its taxonomic description, host range, pathogenicity and antigenic relatedness were investigated. The parasite was infective for black-tailed and white-tailed deer, but with host-specific differences compared to that of bighorn sheep. A splenectomized calf and domestic sheep were refractory to infection. A comparative immunofluorescence assay detected antigens cross-reactive with Babesia odocoilei, B. divergens, B. equi and B. cahalli, but not with B. bovis or B. bigemina. Babesia odocoilei was also infective for bighorn sheep, allowing comparison by a cross-challenge experiment, the results of which supported the conclusion that this parasite was not B. odocoilei. However, the bighorn sheep Babesia cannot currently be distinguished from B. capreoli described from roe deer in northern Germany. Data indicate that, while this parasite may not present a problem for domestic animals, it may cause disease in bighorn sheep and deer populations.