Giant Thorny-headed Worm, Macracanthorhynchus hirudinaceus

The Giant Thorny-headed Worm (Macracanthorhynchus hirudinaceus) is a species of acanthocephalan parasite found in the intestines of pigs and other hoofed animals, and can occasionally appear in humans and dogs. The eggs of this parasite are usually found in scarabaeoid or hydrophilid beetles and other similar insects.

Worms of this species range in size from less than four-hundredths of an inch to over 15 inches. It causes enteritis, gastritis or peritonitis in affected hosts. While it generally does not occur in humans, it does so in regions typically where insects are consumed for dietary or medicinal purposes. Nearly all known human cases have involved infection of the gastrointestinal tract, although one case involved an immature acanthocephalan specimen being removed from a patient’s eye.

This is one of two main acanthocephalans known to infect humans; the other being Moniliformis moniliformis. In infected human hosts, these worms seldom mature and, if they do, they generally do not produce eggs.

Image Credit: An adult Macracanthorhynchus hirudinaceus (Acanthocephala: Archiacanthocephala: Oligacanthorhynchida). Credit: Division of Parasitic Diseases and Malaria team/Wikipedia

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