Unusual case presentation of intestinal Sarcocystis hominis infection in a healthy adult

INTRODUCTION: Sarcocystosis is mainly a veterinary problem; however, humans can serve as the definitive host for at least two species (Sarcocystis hominis and Sarcocystis suihominis). Intestinal infections occur in the definitive host after ingesting the intramuscular cysts (sarcocysts) in the intermediate host, which initiate sexual stages in the intestine that terminate in oocysts excreted in the faeces. CASE PRESENTATION: A 19-year-old male presented with diffuse abdominal pain, watery non-bloody diarrhoea, nausea, vomiting and intermittent low-grade fever that lasted for more than 3 weeks. Multiple stool cultures on enriched and selective media gave negative results. Microscopic examination of wet mounts of stool prepared from formalin/ethyl acetate concentrates, together with permanent staining helped in making a definitive diagnosis and ruling out other coccidian parasites. Diagnosis of the parasite as S. hominis was made based on the size and morphology of the individual sporocysts that were observed in the wet-mount preparations. This severe case of intestinal sarcocystosis in a healthy adult after eating undercooked beef shawarma meat is described. CONCLUSION: The unusual presentation of intestinal sarcocystis described in this case is very rare. The clinical signs and size and morphology of both oocysts and sarcocysts observed in concentrated wet mounts of stool helped in the definitive diagnosis. The food ingested prior to the appearance of symptoms was important in making the definitive diagnosis of the parasite as S. hominis, as well as the incubation period and treatment.