Variations in oocyst output associated with Cryptosporidium baileyi infections in chickens.

Groups of birds, aged 2, 16 and 30 days, were experimentally infected with 400, 20,000 or 1,000,000 oocysts of Cryptosporidium baileyi. The faecal oocyst output for each group was determined by collection of faeces on Days 0, 5, 7 and 13-21 post-infection (p.i.). The duration of patency of infection, as determined by oocyst excretion, declined more rapidly in the older age groups but persisted longer in birds challenged with the lower oocyst numbers.