Abstract
Conjunctival cryptosporidiosis was induced in chicks by ocular inoculation of oocysts of Cryptosporidium sp.(CR) or a wash-solution of the bursa of Fabricius infected with CR. Day-old chicks obtained from P2 White Leghorn chickens were divided into the following groups; ocular inoculation of mature oocysts for chronological examination (Group I); oral inoculation of mature oocysts (Group A); ocular inoculation of wash-solution of the bursa of Fabricius of Group A (Group B); and non-inoculation control group (Group C). Chicks of Group A were necropsied 14 days post inoculation (PI), while Groups I, B and C were necropsied 4, 7, 10, 14 and 21 days PI. Conjunctival cryptosporidiosis was observed in all chicks in Group B, but it was only observed 10 days PI in Group I. Developmental stages of CR were observed in the palpebral and bulbar conjunctiva composed of stratified cuboidal columnar epithelium. The stool of chickens infected CR might have contained mature oocysts, however the wash-solution from the bursa of Fabricius in this study did not contain mature oocysts because of immediate preparation after autopsy. These results suggest that conjunctival infection may occur as a result of direct infection of sporozoites and merozoites derived from meronts and thin-walled oocysts of CR life cycles in the bursa of Fabricius.
