Pathomorphological and histological changes in the cecum and liver of turkeys affected by histomoniasis

Histomoniasis of turkeys is one of the most dangerous protozoan diseases of poultry, causing significant economic losses in the poultry industry and characterized by severe lesions of the digestive system and liver. The material for the study consisted of turkeys with clinical signs of histomoniasis obtained from farms of different ownership types in the Odesa region. A total of 56 clinically affected turkeys of the BIG-6 cross, aged 45–60 days, were examined. Among them, 28 birds that had died were subjected to pathological examination with subsequent sampling of liver and cecal tissues for histological analysis. The diagnosis was established based on a comprehensive assessment of clinical signs, pathological changes, and microscopic detection of Histomonas meleagridis trophozoites in smear-imprints from the cecum and liver stained following the Romanowsky–Giemsa method, as well as the results of histopathological examination. During the clinical examination of infected turkeys, depression, decreased appetite, progressive emaciation, drooping of the head and wings, and diarrhea with characteristic grayish-yellow droppings were recorded. Post-mortem examination revealed lesions typical of histomoniasis in the ceca and liver, including thickening of the cecal walls with the presence of dense yellowish caseous masses in the lumen, as well as hepatomegaly with numerous round necrotic foci of varying sizes. Histological examination revealed pronounced inflammatory and necrotic changes in the tissues of the ceca and liver. The lesions were characterized by transmural typhlitis, necrotic areas, infiltration by mononuclear cells, and a large number of H. meleagridis trophozoites, which were localized both singly and in clusters. In the hepatic parenchyma, multifocal necrotic lesions, degenerative changes in hepatocytes, and inflammatory infiltrates of varying intensity were observed. Prospects for further research are associated with a more in-depth study of the path o genesis of histomoniasis, morphological changes in various organs of poultry, and the development of effective methods for the prevention and treatment of this parasitic infection.