Usually, people are infected when they walk barefoot on contaminated soil.
Most people with this infection do not have any symptoms, but some have a rash, cough, wheezing, abdominal pain, diarrhea, and weight loss.
Rarely, a severe, life-threatening infection develops in people who have a weakened immune system because of a disorder (such as cancer) or drugs that suppress the immune system.
Doctors diagnose the infection by finding larvae in a stool sample or by detecting antibodies to Strongyloides in blood.
Ivermectin or albendazole is used to treat strongyloidiasis.

(See also Overview of Parasitic Infections.)
Strongyloidiasis occurs in warm, moist areas such as the subtropics and tropics, including rural areas of the southern United States.
Strongyloides worms are sometimes called threadworms.