[Muscular sarcocystosis after travel to Malaysia: a case series from Germany]

Since 2011, about 100 travellers to the island of Tioman, Malaysia, have been diagnosed worldwide with suspected muscular sarcocystosis, a previously only sporadically observed parasitic disease. Source of infection and therapy remain unclear. Final diagnosis requires microscopic identification of cysts in muscle biopsies. The study objective was a systematic description of characteristic symptoms, laboratory investigations and treatment response.

Systematic case series.

The 26 cases of 5 centers for tropical medicine in Germany showed a characteristic biphasic development: symptoms began in general 2 weeks after mid-holidays (min. 7.5, max. 22 days) with unspecific fever and headaches lasting for almost 1 week. After an asymptomatic period of 2 weeks, severe myalgia (6.5, scale 0-10) and fever developed and lasted for about 6 weeks (min. 7, max. 207 days), accompanied by creatin-phosphokinase(CK)-elevation (up to 3.5 times), and eosinophilia (2.9 times). One out of two muscle biopsies revealed a cyst typical for sarcocystosis. In 6 out of 7 patients an increase in Sarcocystis-specific antibody concentration could be demonstrated by ELISA. Treatment with systemic steroids and albendazole, or ivermectin resulted in significant symptomatic improvement in most of the patients. One patient was treated early with cotrimoxazole and subsequently did not develop a second phase of the disease. All patients had stayed in the North-West of the island Tioman.

Muscular sarcocystosis develops in a biphasic pattern with initial fever and later prolonged myalgia, eosinophilia, and CK-elevation. Steroids achieve symptomatic relief in the late phase. Early cotrimoxazole-therapy could possibly prevent parasitic muscle invasion. In fever after travel to Malaysia differential diagnosis should include sarcocystosis. The source of infection appears to be located in North-West of Tioman. Further studies are needed, including addressing early diagnosis and treatment.