Strongyloidiasis is caused by infection with Strongyloides stercoralis. Manifestations of infection can range from asymptomatic eosinophilia in immunocompetent host to disseminated disease with septic shock in the immunocompromised host. Strongyloidiasis is endemic in tropical and subtropical regions and occurs sporadically in temperate areas. Burden of adult worms in infected humans can increase substantially via autoinfection. Among immunocompromised hosts, autoinfection can lead to hyperinfection syndrome where there is massive dissemination of filariform larvae to the lungs, liver, heart, central nervous system, and endocrine glands. Most infected patients do not experience prominent symptoms. The most common manifestations are mild waxing and waning gastro-intestinal, cutaneous, or pulmonary symptoms that persist for years; others simply have eosinophilia in the absence of symptoms.