New ruminant hosts and wider geographic range identified for Babesia odocoilei (Emerson and Wright 1970).

Babesia odocoilei was found to infect two previously unknown host species, desert bighorn sheep (Ovis canadensis nelsoni) and musk oxen (Ovibos moschatus), both of which are members of the family Bovidae. Previously, B. odocoilei has been reported in only Cervidae hosts. New geographic regions where B. odocoilei infections have not been reported previously include Pennsylvania and New York, where fatal babesiosis has occurred in reindeer (Rangifer tarandus tarandus); New Hampshire, where elk (Cervus elaphus canadensis) have been affected; and California, home of the infected desert bighorn sheep. Infection with B. odocoilei in these hosts was confirmed by parasite small subunit ribosomal RNA gene sequence analysis. A serosurvey for B. odocoilei antibody activity in New Hampshire showed prevalence rates of 100% at two elk farms and 12% at another farm. Control of potential vector ticks, Ixodes scapularis, especially when translocating livestock, is imperative to prevent outbreaks of babesiosis in managed herds of potential host species.