Sarcocystis hominis identification in slaughtered cattle of Isfahan using light and electron microscope

The parasites of genus sarcocystis are among the most commonly found parasites in domestic ruminants and some species of sarcocystis can generate important economic loss when causing clinical and subclinical diseases. Sarcocystis hominis, one of the three species of sarcocystis that cause muscular cysts in cattle, can infect the human intestinal tract. There is high infection rate of sarcocyst in cattle in the world including Iran but there is not any study about Sarcocystis species identification in Iran. This work aimed to survey existence of S. hominis. In this study, esophagus and diaphragm muscles of 100 cattle were collected from Fesaran abattoir of Isfahan and examined for the presence of S. hominis based on histopathological and ultrastructural characteristics. Histopathological examinations revealed thin and thick walled cysts. S. hominis cysts were observed in 10% of the examined cattle. The cysts had thick, radially striated walls, and were 30-137.5 × 20-70 μm in size and their walls were 2.5 to 6 μm thick. S. hominis cyst walls appeared radially striated in the histopathological sections because of the presence of palisade-like villar protrusions. Ultrastructural features of the protrusions by TEM, were broad-based, blunt distal end, cylindrical, contained microtubules, and oriented nearly perpendicularly to the sarcocyst surface. Based on histopathological and ultrastructural features of the cysts, we identified them as S. hominis.