Hexamitiasis is an acute infectious disease of turkeys, quail, ducks, chukar partridges and pigeons. Heavy losses have been reported in one outbreak in ring-necked pheasants. Chickens apparently are not affected.
Hexamitiasis is a problem in every commercial turkey-producing area. It may be a major problem in localized areas during a particular year, followed by one or more years in which incidence is low.
Hexamitiasis is caused by a one-celled parasite of the genus Hexamita. Hexamita meleagridis is the cause in turkeys; in pigeons it is Hexamita columbae. Experimentally, the Hexamita of turkeys can be transmitted to young quail, chicks and ducklings, and that of quail and partridges can be transmitted to poults. However, poults cannot be infected with the organism isolated from pigeons.
This disease is found primarily in young birds, and outbreaks seldom occur in poults past ten or eleven weeks. Losses are most severe in birds three to five weeks old. Apparently, resistance develops rapidly with increasing age, regardless of previous exposure.
The primary infection source is droppings from carrier birds. About a third of recovered birds become carriers. 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. Birds often huddle together near the heat source and cry or "chirp" constantly as though in pain. 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. A definite diagnosis cannot be made unless typical flagellated organisms can be detected in intestinal contents of the duodenum. Most flagellate organisms in the cecae are not disease producers.