Coccidiosis in Sistan: the prevalence of Eimeria species in native chicken and its histopathological changes

Coccidiosis is an important disease in the poultry industry caused by species of protozoan parasites belonging to the genus Eimeria (phylum Apicomplexa); it results in a great economic loss all over the world. The aim of this study was to determine the frequency and diversity of Eimeria species, the effect of season on the prevalence of coccidiosis in poultry, and the evaluation of its histopathological changes in native infected chickens in different parts of Sistan. A total of 2792 samples selected through random cluster sampling of chickens from areas of Sistan (Zabol, Hirmand, Nimrooz, and Zehak) and their infected organs especially intestines were examined for histopathological studies. Out of the 2792 samples processed, 585 samples were found to be positive for coccidiosis with a prevalence of 20.95%. Coccidiosis was initially diagnosed on the basis of fecal examination and confirmed by the presence of sporulated oocysts and pathomorphological alterations in the intestines. Five Eimeria species identified by morphometry were Eimeria acervulina, E. maxima, E. brunetti, E. necatrix, and E. tenella. Based on the results of the experiments, the percentage of coccidiosis infection in cold seasons (October–March) was higher than in the warm seasons (April–September). Histopathological lesions revealed loss of epithelial tissue, congestion of blood vessels which indicate disruption followed by hemorrhage, severe muscular edema, and necrosis of the submucosa of the intestine and cecum. There was loss of intestinal villi, disruption of cecal mucosa, and clusters of oocysts seen. Also, there was massive infiltration by a large number of inflammatory cells including eosinophil, lymphocyte, and plasma cells. Several merozoites, schizonts, microgametes, and macrogametes were found in the epithelial cells.