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 tax onomic description, host range, pathogenicity and antigenic relatednes s were investigated. The parasite was infective for black-tailed and w hite-tailed deer, but with host-specific differences compared to that of bighorn sheep. A splenectomized calf and domestic sheep were refrac tory to infection. A comparative immunofluorescence assay detected ant igens cross-reactive with Babesia odocoilei, B. divergens, B. equi and B. cahalli, but not with B. bovis or B. bigemina. Babesia odocoilei w as also infective for bighorn sheep, allowing comparison by a cross-ch allenge experiment, the results of which supported the conclusion that this parasite was not B. odocoilei. However, the bighorn sheep Babesi a cannot currently be distinguished from B. capreoli described from ro e deer in northern Germany. Data indicate that, while this parasite ma y not present a problem for domestic animals, it may cause disease in bighorn sheep and deer populations.