Parasitology Diagnostic Laboratory

Necator americanus (Hookworm)

The image below is of Necator americanus. Eggs of the roundworm Necator americanus are found warm moist soil, and contain filariform larvae that can penetrate human skin. Once under the skin, the larvae migrate through the heart and lungs. From the lungs they are coughed up and swallowed, finally arriving in the small intestine where they mature into adults. Diagnostic thin-shelled eggs in the stool are oval, approximately 60 x 40 µm with a space between the shell and the developing embryo, which typically consists of 8 to 32 cells. These eggs are indistinguishable from those of the hookworm Ancylostoma duodenale.