Diffuse and massive endocardial sarcocystosis in a lamb

Sarcocystosis is an important parasitic zoonosis caused by Sarcocystis species, an intracellular protozoan parasite of the Apicomplexa phylum and one of the most prevalent parasitic diseases among wild and domestic animals all around the world. Infection in the definitive host is mainly characterized by the formation of cysts in muscle tissue. In intermediate host skeletal muscles, diaphragm and heart are the favored locations for Sarcocystis spp. While we were examining the heart of a dead, three-month old lamb, incidentally, we observed striking, white and discrete spots, measuring 2-3 mm, that were diffusely distributed in endocardium. Microscopically, numerous sarcocysts were seen within cardiomyocyts and purkinje fibers. No different pathological modifications had been found in inflamed muscle fibers or surround interstitium. To the best of our knowledge, there is no case report about diffuse involvement of endocardium by Sarcocystis spp. and this uncommon form of sarcocystosis prompted us to place the current case on record.