Prevalence and pathologic changes due to Sarcocystis species in naturally infected sheep in Urmia city, Iran

Sarcocystis species in animals and humans cause a zoonotic disease called Sarcocystosis. This study was aimed to investigate the morphology and pathology of Sarcocystisin naturally infected sheep. The carcasses of slaughtered sheep at Urmia slaughterhouse were inspected for evidence of infection with Sarcocystis macrocysts. Histopathological sections were prepared and stained routinely by Hematoxylin-Eosin (H&E) staining. A total of 1372 out of 4121 (33.3%) removed macrocysts were full of bradyzoites (54.3×223.66μm) ranged from 5-10 mm. Histologically, the reaction of the muscle tissue varied from degenerative to inflammatory around the macrocysts. The infected muscle demonstrated evidence of myocytolysis with infiltration of inflammatory cells in focal pockets, which were mainly comprised of lymphocytes and macrophages. The other findings were arterial wall hyperplasia, hyperplastic proliferation, and giant cell presence around the macrocysts. The results indicated that morphologic features of macrocysts of Sarcocystis in naturally infected sheep were informative and causing pathologic changes in muscle tissue.