Most outbreaks result from a buildup of organisms through several broods of poults, making exposure of the following brood overwhelming. Indirect transmission may result from fecal material carried from one location to another on shoes or equipment. Free-flying birds also may be carriers. Primary symptoms are listlessness and foamy or watery diarrhea with rapid weight loss due to the dehydrating effect. Convulsions due to lowered blood sugar levels shortly precede death.
Affected birds suffer losses in weight and survivors remain stunted.
Dehydration and emaciation are the principal gross lesions. Muscles are dark and dry. The intestine usually appears to have lost muscle-tone. Intestinal contents are usually thin and watery, or may contain mucus. Diagnosis depends upon history, symptoms and microscopic examination of intestinal contents.