Sarcocystis was identified in biopsy specimens of skeletal muscle from two adults in Singapore and one in Bombay, and in muscle obtained at autopsy from an adult in Uganda, and in the heart of a child in Costa Rica. Review of case reports revealed that in seven reported cases, including three reported by Lindemann, non-parasite objects were misinterpreted as sarcocysts; in four instances organisms of undetermined classification were described, and in 35 cases true sarcocysts were observed. Among the sarcocysts seen in the 40 cases (35 old, 5 new), seven morphological types were recognized, each representing one to several different species, all of which are zoonotic and none of which can be designated Sarcocystis lindemanni. Among the four types of sarcocysts found in skeletal muscle, three closely resembled a corresponding species found commonly in monkeys: one from a man in Uganda corresponding to a species in Cercopithicus talapoin, forms from India resembling one or two species in Macaca mulatta, and forms from Southeast Asia resembling a species in Macaca fascicularis. Among three types of sarcocysts found in the human heart, one resembled a species commonly seen in the heart of cattle. Of the 40 Sarcocystis infections in man, 13 probably were acquired in Southeast Asia, 8 in India, 5 in Central or South America, 4 each in Africa and Europe, 3 in USA, 1 in China and 2 in unknown localities. Associated conditions include muscle soreness or weakness in 7 cases, subcutaneous swellings in 5, eosinophilia in 2, and periarteritis or polyarteritis nodosa in 2 cases. However, evidence of pathogenicity of the mature sarcocyst is inconclusive.
