Sarcocystis

Excerpt

Sarcocystis species are intracellular protozoan parasites. They were first reported by Miescher in 1843 as white threadlike cysts in the striated muscles of a house mouse, and they were referred to as Miescher tubules for the next 20 years. For many decades, it was unclear whether they were protozoa or fungi. Similar structures were found in 1865 in pig muscle. Subsequently, in 1967, these spindle or crescent-shaped bodies were studied under electron microscopy, and organelles were observed like those in apicomplexan protozoans of Toxoplasma and Eimeria.

Sarcocystis species have a heteroxenous (ie, more than 1 obligatory host) life cycle based on a prey-predator host relationship of definitive and intermediate hosts, identified in 1972. Over the years, about 150 symptomatic human cases have been reported, with more than 100 Sarcocystis spp known; most have been isolated from muscle tissues of various intermediate hosts, including mammals, birds, and reptiles. See Image. Life Cycle.