Ancylostoma and Necator (Old World and New World hookworms)

The nematodes, Ancylostoma duodenale and Necator americanus, each about 1 cm in body length, are distributed worldwide. Before World War II, numerous cases were known in Japan, but now the infection has become rare. Humans get infected either by eating fresh vegetables contaminated with the infective larvae or by walking barefoot on contaminated soil, allowing larvae to penetrate the skin. The nematodes suck blood from the intestine, using the teeth around their mouth, and may cause anemia.