Strongyloides stercoralis (threadworm) – Free-living female and larvae

This free-living female (A) is about 1.1 mm long, and 40 µm wide. Eggs are produced that rapidly transform into 1st-stage rhabditiform larvae (B) that are 200-300 µm in length, and 15-18 µm in width. These larvae molt then develop into infective 2nd-stage or filariform larvae, that are 500-600 µm in length, and 15-20 µm in width.