|Esposito, Douglas - Centers For Disease Control And Prevention (CDCP) - United States|
Submitted to: Clinical Microbiological Reviews
Publication Type: Review Article
Publication Acceptance Date: 2/1/2015
Publication Date: 2/25/2015
Citation: Fayer, R., Esposito, D., Dubey, J.P. 2015. Sarcocystis in Humans. Clinical Microbiological Reviews. 28(2):295-311.
Interpretive Summary: Sarcocystis is a protozoan parasite affecting a wide range of hosts including livestock, wildlife, birds, and humans. The life cycle and disease aspects were reported by ARS scientists several years ago and those related publications have served in large part as a guide for diagnosing and determining the sources of the disease in humans. Recently ARS scientists have served as advisors to the Centers for Disease Control involving an outbreak of muscular Sarcocystis in persons, mostly from Europe on holiday in Malaysia, who returned home with symptoms remarkably similar to those reported in cattle and sheep by ARS scientists. A second outbreak was reported among Malaysian students who visited another island. The present manuscript has compiled all published reports on human infections, microscopic and molecular detection methods, animal sources when known, the clinical signs of intestinal and muscular infections, geographic location of infected persons, and treatment strategies. This report will serve as the most comprehensive guide for veterinarians, physicians, epidemiologists and other health care workers encountering this parasitic disease in humans.
Technical Abstract: Humans serve as definitive hosts for two known species of Sarcocystis, acquired from eating undercooked pork or beef, and resulting in gastrointestinal infection. Sporocysts excreted from these infected persons are each infectious for pigs and cattle, the intermediate hosts, resulting in the development of infectious cysts in the meat. Humans can also serve as accidental intermediate hosts with muscular sarcocystosis for unknown species in which it is presumed that primates are the natural intermediate hosts and reptiles or other carnivores are the definitive hosts. Recently, clinicians evaluating travelers returning ill from Malaysia with fever and myalgia noted the biphasic aspect of the disease, reported earlier by ARS scientists for cattle, and sheep, including elevated serum enzyme levels, eosinophilia, myalgia (100%), fatigue (91%), fever (82%), headache (59%), and arthralgia (29%). Sarcocystis nesbitti DNA was recovered from one biopsy sample, indicating for the first time that a reptile was the source of the parasite causing human infection and contaminated water was the likely method of transmission. Details of the life cycle of Sarcocystis species and attempts at prophylaxis in experimental animals and therapy in humans are included in this report.