Oocyst production, late-stage merogony, gametogony, and cross-transmission studies of Eimeria bubonis (Protozoa: Eimeriidae) of the great horned owl, Bubo virginianus
The study was designed to examine oocyst production, endogenous development and host specificity of Eimeria bubonis (Protozoa: Eimeriidae). Three great horned owls were administered 1.0 × 104 sporulated oocysts of E. bubonis orally. Three more great horned owls were each fed two mice which had been previously intubated with sporulated oocysts of E. bubonis. Feces were examined daily after flotation and oocyst production was estimated. One great horned owl was administered 2.25 × 105 sporulated oocysts of E. bubonis, killed 5.5 days later and examined histologically. Domestic chicks were administered oocysts of E. bubonis and their feces examined as above. Mice were administered sporulated oocysts of E. bubonis and then killed sequentially. Tissues of chickens and mice were examined histologically. The prepatent period of E. bubonis in great horned owls was 5.0–6.0 days; the patent period was as short as 4–6 days. Maximal oocyst production occurred 6–7 days after infection. Endogenous development occurred distal to nuclei of villar epithelial cells in the anterior half of the small intestine. E. bubonis was not transmissible to chickens. Pyogranulomas developed and persisted 12 weeks in mice administered E. bubonis; however, there were no stages of E. bubonis infective to great horned owls.