Abstract
In an outbreak of diarrhea among 82 artificially reared red deer calves, 56 developed the disease and 20 subsequently died. During the outbreak 80% of diarrheal and 50% of apparently healthy calves excreted cryptosporidial oocysts in feces. The coincidence of infection with Cryptosporidium and clinical diarrhea suggested a causal relationship. Histologic examination of intestinal sections from a necropsied deer calf showed lesions consistent with field and experimental cryptosporidiosis in other species. The deer Cryptosporidium subclinically infected newborn mice; in indirect immunofluorescence tests, it could not be distinguished from a calf Cryptosporidium.