Sarcocystis species in wild and domestic sheep (Ovis ammon and Ovis aries) from China

Background Sarcocystis species are intracellular protozoan parasites that can pose a threat to animal health and food safety. The aim of this study was to investigate the prevalence of infection with Sarcocystis infection in sheep from China. Results In total, 52.51% (335/638) of tissue samples from domestic sheep contained sarcocysts through examination by light microscopy. The organisms were identified as S. tenella and S. arieticanis by molecular assays. Macroscopic S. gigantea and S. medusiformis were not found. The average sarcocysts loading was 18.07 ± 29.87 per square centimeter in the myocardium of domestic sheep. Furthermore, two specimens of argali (Ovis ammon) were examined and sarcocysts were found in the myocardium of one animal. According to the sequence of the cox1 gene of sarcocysts from argali, it was speculated as S. tenella. Conclusions We found a high prevalence and parasite load of Sarcocystis in sheep from both central and northwest China. This report is the first to indicate that argali may be a natural intermediate host for S. tenella.