Interaction of reovirus and Cryptosporidium baileyi in experimentally infected chickens.

No clinical signs, gross lesions, or increased mortality were observed in specific-pathogen-free chickens orally inoculated at 5 days of age with Cryptosporidium baileyi, reovirus 2035, reovirus 2408, or combinations of these agents. Weight gain of chickens inoculated with only reovirus 2408 was depressed 0-8 days postinoculation (PI) (P less than 0.01) but not for the 21-day period PI. Weight gain of chickens inoculated with only reovirus 2035 was not affected. Cryptosporidium baileyi infection significantly depressed weight gain 8-14 days PI but not for the entire 21-day period PI. Weight gain of chickens infected with both C. baileyi and reovirus 2035 was significantly depressed 0-14 days PI and for the entire 21-day period PI. Dual infection with C. baileyi and either reovirus appeared to promote shedding of both agents. Cryptosporidia were found principally in the rectum 2-10 days PI and in the bursa of Fabricius 6-10 days PI. Reovirus infection did not cause any microscopic lesions and did not modify lesions caused by C. baileyi infection.