Histopathology of hemorrhagic enteritis in turkeys

In the summer of 1972, a disease of turkeys manifesting hemorrhagic diarrhea as a main clinical symptom and hemorrhagic enteritis as a necropsy finding broke out on a turkey farm in Japan. Seven-week-old Large White turkeys suffering from this disease were studied histopathologically and electron microscopically. Clinically, affected birds showed bloody diarrhea. Death occurred to them after an acute course. In the blood film, immature monocytes were higher in count in them than in healthy birds. Necropsy revealed a number of dark red bloody clots in the intestinal tract, many petechiae in the mucous membrane of small intestine and ceca, and atrophy of the spleen. The histopathological changes characteristic of this disease were acute hemorrhagic enteritis, degenerative changes of lymphatic tissue, proliferation of reticuloendothelial cells all over the body, and formation of intranuclear inclusion bodies in these cells. By electron microscopy, viral particles showing a crystalline array were found in the nuclei of reticuloendothelial cells. Viral particles which had electron-dense nucleoids and a naked hexagonal shape were about 80 nm in average diameter. The ultrastructural features of those inclusion bodies were identical with those of avian adenovirus.