What pathological changes occur in chronic intestinal coccidiosis in chickens?

The lesions of chronic intestinal coccidiosis in chickens are mainly located in the middle section of the small intestine and the duodenum. The intestinal tract is markedly enlarged, and a large number of millet-sized red hemorrhagic spots or grayish-white necrotic spots can be seen from the serosal surface of the intestinal tract. When the intestinal tract is cut open, the intestinal mucosa is seen to be inflamed and swollen with a rough surface, and the intestinal contents consist of thick, viscous exudate, often mixed with small blood clots.