Strongyloides stercoralis (threadworm) – Free-living female

This free-living female is approximately 1 mm long and 60 µm in diameter, and the esophagus is rhabditiform. Conversely, the parasitic parthenogenetic female is about 2.2 mm long, and 50 µm in diameter. On this pic, half a dozen of eggs are well visible in the uterus. The worm is surrounded by a few Trichuris trichiura eggs.