Studies on the life cycle of Cryptosporidium coccidia in experimentally infected chickens.

Experimental infections of 7-28-day-old chickens with Cryptosporidium oocysts isolated from spontaneously infected chickens demonstrated that the endogenous development of this parasite takes place simultaneously in the organs of digestive, respiratory and excretory systems and in bursa of Fabricius. It was demonstrated for the first time that the oocysts of Cryptosporidium are shed through the respiratory tract into the beak cavity. A novel rapid and simple method has been developed for the detection of oocysts. Its principle is the rinsing of the beak cavity. This method enabled to isolate the oocysts from experimentally infected chickens and immediately use them in the dose of 6 X 10(5) for peroral infection of a 37-day-old chicken. The prepatent period was 8 days, patent period 12 days. On days 4-7 after the first detection of Cryptosporidium oocysts in chicken excrements, the oocysts were detected also by the method of beak cavity rinsing. This indicates that the oocysts released from the respiratory tract are infective. This fact is important from the epizootological viewpoint in relation with possible spreading of Cryptosporidium infections in chicken farms.