Strongyloidiasis is the disease caused by the Strongyloides stercoralis parasite. This organism is an intestinal nematode with worldwide distribution, but is especially common in tropical and subtropical regions. The disease usually manifests as intestinal symptoms (mild diarrhea). In a minority of cases, the organism will become extra-intestinal and may lead to septic shock and meningitis.

Serological tests are useful in detecting infection by Strongyloides if the organism goes extra-intestinal and in excluding the organism from the diagnosis of other disorders (especially hematologic malignancies). Strongyloides infected patients are particularly at risk for severe complications if they are also immunocompromised.