Miscellaneous Intestinal Nematodes

Macracanthorhynchus hirudinaceus: This species is a common parasite of pigs. Humans will also serve as the definitive host, but only a few such infections have been reported. (It is possible that many infections in humans go unreported.) The adult worms are found in the definitive host's small intestine. Female worms measure up to 60 cm long, while males generally do not exceed 10 cm. Such sexual dimorphism is common in the Acanthocephala.
An egg of Macracanthorhynchus hirudinaceus. The eggs of this species measure about 80µm in length.