TABLE OF CONTENTS
Macracanthorhynchus hirudinaceus (Thorny-Headed Worm)
Macracanthorhynchus hirudinaceus, commonly known as the giant thorny-headed worm of swine, is an acanthocephalan parasite that primarily infects pigs. It is characterized by a retractable proboscis armed with rows of recurved hooks, which firmly attach the parasite to the intestinal wall. Although infections are often subclinical, heavy parasite burdens can cause intestinal inflammation, granuloma formation, and, in severe cases, intestinal perforation and peritonitis.
The life cycle of Macracanthorhynchus hirudinaceus is indirect and requires dung beetles as intermediate hosts. Pigs become infected by ingesting infected beetles while rooting in contaminated environments.
Parasite Overview
- Common Name: Thorny-headed worm
- Definitive Host: Pig
- Predilection Site: Small intestine
- Intermediate Host: Dung beetle
Taxonomical Classification
- Kingdom: Animalia
- Phylum: Acanthocephala
- Class: Archiacanthocephala
- Order: Oligacanthorhynchida
- Family: Oligacanthorhynchidae
- Genus: Macracanthorhynchus
- Species: Macracanthorhynchus hirudinaceus
- Common Name: Giant thorny-headed worm of swine
Morphology
The female measures approximately 35 cm, while the male measures approximately 10 cm. The cuticle is transversely wrinkled. The proboscis is small and armed with six rows of recurved hooks.
Life Cycle
Pigs become infected by ingesting infected beetle larvae or infected adult beetles.
Pathogenesis
The worms attach to the mucosa of the small intestine, causing inflammation and granuloma formation at the site of attachment. In some cases, the worm may penetrate the intestinal wall, resulting in peritonitis.
Clinical Signs
Emaciation and weight loss.
Diagnosis
Fecal examination for the presence of eggs.
Treatment
- Levamisole: 7.5 mg/kg body weight (oral)
- Ivermectin: 0.5 mg/kg body weight (SC)
