Recurrent isosporiasis over a decade in an immunocompetent host successfully treated with pyrimethamine.

Recurrent isosporiasis in an immunocompetent host is reported. The patient suffered from chronic intermittent diarrhea for over a decade. Multiple short-term administrations of trimethoprim-sulfamethoxazole followed by pyrimethamine, or albendazole combined with tinidazole could not control the relapses. However, treatment with pyrimethamine, 25 mg/d for 20 weeks, was successful.