1. An economically important genus of nematode parasites (family Trichostrongylidae) occurring in the abomasum of ruminants and causing severe anemia, especially in younger or previously unexposed animals. Some significant species are Haemonchus placei (in cattle, sheep, and goats), Haemonchus similis (in cattle and sheep), and Haemonchus contortus, the stomach, barberpole, or twisted wire worm of cattle, sheep, goats, and other ruminants, of which a few cases have been reported from humans; accidental parasite of humans.
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