The Sarcocystis-Cyst Containing Beef and Pork as the Sources of Natural Intestinal Sarcocystosis in Thai People
Sukhum Bunyaratvej MD*, Piyapong Unpunyo MD**, Atcharaporn Pongtippan MD*
Affiliation : * Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok ** Division of Pathology, Lampang Hospital, Lampang
Background : Human intestinal sarcocystosis is a zoonotic disease caused by two coccidians, i.e. Sarcocystis
fusiformis (syn. S. bovihominis, S. hominis) due to consumption of raw infected beef, and Sarcocystis
meischeriana (syn. S. suihominis) due to consumption of infected raw pork. In 1987, survey of the macroscopic
S.fusiformis cysts in market beef mainly from old water buffalos aged more than 15 years were commonly
observed in Bangkok. In 2005, the macroscopic cyst was no longer seen in beef of cattle and water buffalo
aged less than three years.
Objective : The epidemiological investigation of Sarcocystis spp. infected meat in Bangkok and Lampang.
Materials and Methods : Samples for each of the tongue and beef of cattle and water buffalo, pork from Bangkok
markets and pork of domestic swine from some remote villages in various subprovinces (Ampurs) in Lampang
were obtained for microscopic examination by H and E and selectively by PAS staining.
Results : The microscopic S. fusiformis cysts were seen in all five specimens of tongues and ten specimens of
muscles of cattle and water buffalo obtained from fresh-food markets in Bangkok. Ten samples of pork from
Bangkok markets revealed no coccidian infection. The microscopic S. meischeriana cysts were seen in three
specimens of swine muscles collected from two subprovinces in Lampang.
Conclusion : The present merozoites in coccidian cysts retrieved from beef and pork are similar to those
previously observed in human intestine. This may histologically indicate an invasive sarcocystosis by both
species leading to a condition presently known as chronic inflammation of undetermined etiology in man.
Keywords : Sarcocystis fusiformis, Sarcocystis bovihominis, Sarcocystis meischeriana, Sarcocystis suihominis
