Experimental infections of Eimeria wapiti and E. zuernii-like oocysts in Rocky Mountain elk (Cervus elaphus) calves.

Four Rocky Mountain elk (Cervus elaphus) 10 to 14 wk of age each were inoculated orally with a mixture of 50,000 sporulated oocysts of an Eimeria zuernii-like apicomplexan (70%) and E. wapiti (30%). Maximum numbers of oocysts per gram of feces (OPG) in each elk ranged from 985 to 15,517, but all calves remained healthy and clinical signs of coccidiosis were not observed. The prepatent period for E. zuernii was 8 days and the patent period approximately 37 days, with a maximum mean (+/- SE) recovery of 6,643 (+/- 3,756) OPG on post-inoculation day 8. The prepatent period for E. wapiti was 10 to 12 days and the patent period approximately 8 days, with a maximum mean recovery of 4,408 (+/- 2,308) OPG on postinoculation day 12. Based on these data, infections of E. zuernii and E. wapiti at the numbers given were not pathogenic in healthy elk calves.