Strongyloidiasis is the condition of being infested with Strongyloides worms, most importantly Strongyloides stercoralis in humans. This small roundworm has an unusual life cycle: larvae in contaminated soil penetrate intact skin — typically the bare feet of people walking on infected ground — travel through the bloodstream to the lungs, are coughed up and swallowed, and mature in the small intestine. Light infections may cause only itching or mild gut symptoms, but in immunocompromised people the worms can multiply uncontrollably in a life-threatening hyperinfection. The disease is common in tropical and subtropical regions with poor sanitation. Diagnosis is by stool examination, treatment with antiparasitic drugs such as ivermectin, and prevention by sanitation and footwear.