What are the clinical symptoms of avian cecal hepatitis (histomoniasis) in chickens?

Chickens affected by cecal hepatitis are listless, with reduced or completely lost appetite, often huddling with the neck drawn in and standing still, wings drooping, and unwilling to move. The feathers are rough and lusterless, with jagged tips. The droppings are pale yellow or pale green, and in acute cases are loose and bloody. In the late stage of the disease, due to impaired blood flow, the head turns blue-purple or black, which is why people call it "blackhead disease." The cloacal temperature rises above 42 degrees and drops below 40 degrees before death.