CDC : Acute Muscular Sarcocystosis Among Returning Travelers - Tioman Island, Malaysia, 2011

Morbidity and Mortality Weekly Report (MMWR)from CDC, excerpt :

" GeoSentinel (the surveillance program of the International Society of Travel Medicine and CDC) has identified 32 cases of suspected acute muscular sarcocystosis in travelers returning from Tioman Island off the east coast of peninsular Malaysia. All the patients traveled to Tioman Island during the summer of 2011. Within days or weeks of returning home, all experienced fever and muscle pain, often severe and prolonged. All had peripheral eosinophilia, and most had elevated serum creatinine phosphokinase levels. Most were tested for acute trichinosis and toxoplasmosis by serology, and all of these tests were negative. Approximately half of the patients were identified in Germany; others were reported elsewhere in Europe, and in North America and Asia. Muscle biopsy from two patients demonstrated organisms consistent with sarcocystosis, one from a group of five ill travelers and one from a group of three.

Sarcocystis spp. are intracellular protozoan parasites.* Humans are the definitive host for Sarcocystis hominis and Sarcocystis suihominis, acquired by eating undercooked sarcocyst-containing beef or pork, respectively. The parasites reproduce sexually in the human intestine, where infection can cause acute gastroenteritis; however, most S. hominis and S. suihominis infections are thought to be asymptomatic (1). Although the specific species have never been identified, humans can become intermediate hosts for at least some of the 130 Sarcocystis spp. that are transmitted between predator and prey in nature. In these cases, humans ingest oocysts or sporocysts in food or water contaminated with feces from an infected predator animal. Nonspecific symptoms might arise during the reproductive and migratory phase of the parasite within the vascular endothelium. The parasite ultimately disseminates to skeletal, cardiac, and smooth muscle, where it forms sarcocysts containing large numbers of parasites that are infectious for a definitive host. Sarcocyst formation can provoke eosinophilic myositis, as occurred in this outbreak. No proven treatment exists for human muscular sarcocystosis, but in all previously reported cases, symptoms resolved over weeks to months."