Prevalence of Sarcocystis spp. in Sheep Cardiac Tissue at Al Bayda Municipal Abattoirs: A Histological Cross-Sectional Study

Abstract

Sarcocystis is an intracellular cyst-forming protozoan parasite belonging to the phylum Apicomplexa. It infects a wide range of vertebrates, including sheep, and has significant veterinary and public health importance. This study aimed to determine the prevalence of Sarcocystis spp. Infection in cardiac tissues of slaughtered sheep at the municipal abattoirs of Al Bayda, Libya, using histopathological examination, focusing on cases with no visible macroscopic cysts. Fresh cardiac tissue samples were collected from 50 slaughtered sheep (both sexes and various ages) between May 2025 and April 2026 from hearts lacking visible macroscopic sarcocysts. Tissues were fixed in 10% neutral buffered formalin, processed by routine histological methods, sectioned at 5 µm thickness, and stained with Harris's hematoxylin and eosin (H&E) for microscopic examination. Histopathological examination revealed Sarcocystis infection in all 50 samples (100% prevalence). Microscopic thin-walled sarcocysts with similar morphology were observed in cardiac tissues, while no macroscopic cysts were detected by naked-eye inspection. No inflammatory reaction was observed around the sarcocysts (absence of pericystic inflammatory infiltrates), and no prominent degenerative or inflammatory changes were noted in the infected cardiac tissue. The study concludes that Sarcocystis infection is highly prevalent (100%) in the cardiac tissue of sheep slaughtered in Al Bayda abattoirs, with the absence of macroscopic cysts and lack of pericystic inflammation. Histopathological examination is of great diagnostic value for detecting Sarcocystis infection, especially when macroscopic lesions are absent, and gross examination alone is insufficient to estimate the true prevalence of the parasite.