Human Invasive Muscular Sarcocystosis Induces Th2 Cytokine Polarization and Biphasic Cytokine Changes, Based on an Investigation among Travelers Returning from Tioman Island,

Sarcocystis nesbitti is a parasite responsible for a biphasic eosinophilic febrile myositis syndrome in two recent outbreaks in Ma-laysia. We demonstrate Th2 cytokine polarization in infected travelers, an overall cytokine production decrease in the early phase of the disease suggestive of initial immunosuppression, and elevated levels of proinflammatory and chemotactic cytokines in the later myositic phase. Muscular sarcocystosis, a parasitic zoonosis that has onlyrarely been reported clinically in humans in Southeast Asia (1), has come to recent attention because of two concomitant outbreaks in Malaysia. One outbreak occurred in 2012 on Pang-kor Island, located on the west coast of peninsular Malaysia (2, 3), and involved 89 students and teachers, mostly from Asia. The other one took place in two successive waves in 2011 and 2012 on Tioman Island, located on the east coast, and affected100 inter-national travelers (4–7). A third wave of infected travelers return-ing from Tioman Island was reported in 2014 (8), indicating an ongoing transmission from a still unknown source. Transmission on Pangkor Island has been linked to contaminated freshwate