The most easily recognized clinical sign of severe cecal coccidiosis is the presence of bloody droppings. Dehydration may accompany cecal coccidiosis. Coccidiosis caused by E. tenella first becomes noticeable at about three days after infection. Chickens droop, stop feeding, huddle together, and by the fourth day, blood begins to appear in the droppings. The greatest amount of blood appears by day five or six, and by the eighth or ninth day, the bird is either dead or on the way to recovery.
Mortality is highest between the fourth and sixth days.
Death may occur unexpectedly, owing to excessive blood loss. Birds that recover may develop a chronic illness as a result of a persistent cecal core. However, the core usually detaches itself by eight to ten days and is shed in the droppings. Coccidiosis caused by E.tenella developing in the ceca. The arrow indicates the cecal core E. necatrix causes a more chronic disease than E. tenella and does not produce as many oocysts.