Studies on Excystation of Coccidial Oocysts

Abstract

Attempts to induce in vitro excystation of viable sporulated oocysts of Eimeria nieschulzi by exposing the oocysts to the action of digestive enzymes and digestive fluids, changes in oxidoreduction potentials, air pressure, and vacuum, and fresh blood were unsuccessful. When sporulated oocysts are injected into the blood stream, skeletal muscle, or the peritoneal cavity of the host, they will excyst. A typical infection is established in the host following the injection of the sporulated oocysts into skeletal muscle or the peritoneal cavity. The host may be reinfected in the same manner but, following recovery from the second infection, when these hosts were fed or injected with oocysts, they produce only a few complete oocysts and moderate numbers of degenerate or incomplete oocysts probably because of the development of a cellular reaction to endogenous stages.