The coccidian Caryospora bubonis in the great horned owl (Bubo virginianus)

Three Bubo virginianus each fed 5000 sporulated oocysts of Caryospora bubonis passed oocysts in their faeces after 11 to 13 days, peak oocyst production occurring between days 14 and 18. Three owls each fed 2 infected mice (dosed 4 weeks earlier with 25 000 C. bubonis oocysts) shed oocysts after 8 to 10 days, peak production occurring between days 9 and 13. Two types of mature schizonts, one containing many merozoites and one containing up to 4, were found in an owl killed 12 days after infection with 125 000 oocysts. Macro- and microgamonts were also seen in the epithelial cells of the intestine. The shortening of the prepatent period in owls fed infected mice shows that both direct and indirect life-cycles can oocur in C. bubonis..