Strongyloides stercoralis is a parasitic nematode that can cause the disease strongyloidiasis. It has a complex life cycle involving both free-living and parasitic stages. The parasite penetrates intact skin and has two life cycles - an intestinal cycle that can persist for decades, and a pulmonary cycle seen in severe infections. Symptoms range from mild skin symptoms to severe pneumonia-like symptoms. Diagnosis involves examining stool, sputum, or gastric/duodenal samples for eggs or larval stages. Treatment involves ivermectin and albendazole. Prevention relies on good hygiene and sanitation practices.