Parasitology Diagnostic Laboratory

Strongyloides stercoralis

The image below is of Strongyloides stercoralis. Strongyloides stercoralis is an intestinal nematode with a very complex life cycle. Infection occurs when filariform larvae in the soil penetrate the skin and are carried in the blood to the lungs. From the lungs they travel up the trachea and are swallowed. Once in the intestine they develop into mature female worms that begin to produce eggs. These eggs, which are rarely seen, hatch in the intestine into rhabditiform larvae, the diagnostic stage. These larvae are 180-380 µm, and typically have a short buccal cavity and a prominent genital primordium. They are excreted into the feces, and once in the soil, develop into both male and female worms to complete the life cycle.