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Thorny-headed Worm (Macracanthorhynchus hirudinaceus)

(505) These measure 100-400mm in length and are found in the intestine. The heads contain large hooks which hold the worm to the small intestinal wall and they cause nodular lesions. They are found in both temperate and tropical climates.

The life cycle

This is indirect, the larvae are eaten by the grub of the May beetle. The pig must then eat these to complete the cycle. The worms are prolific egg layers but it is an uncommon parasite.

Clinical signs

Large numbers can cause considerable damage to the small intestine and large numbers of nodules are formed. Mild diarrhoea and loss of condition occur.


  • See Fig.11-9. below
Management control and prevention
  • See introduction.

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