Bacterial Population Changes in the Ceca of Young Chickens Infected with Eimeria tenella

Abstract

Eimeria tenella, a protozoan parasite belonging to the class Sporozoa, is the etiological agent of cecal coccidiosis of chickens. This organism goes through a typical sporozoan life cycle and, with the exception ofsporulation of the oocyst, all stages occur within the host's intestinal tract. Invasion of the intestinal epithelium by sporozoites and merozoites results in considerable tissue destruc-tion and, in acute cases, severe hemorrhaging by the fifth day of infection, at which time mortality among the hosts reaches a peak. It has been known for some time that under certain poorly defined conditions intestinal bacteria of the chicken may invade the tissues and set up local infec-tions in the liver, spleen, and other organs. Morse (1908) frequently foun