Prosthogonimus macrorchis

Prosthogonimus macrorchis, commonly referred to as the oviduct fluke, is an avian parasite found in regions of the United States and Canada near the Great Lakes. It is known for causing a reduction or termination in egg production in domestic fowl. The parasite inhabits mainly aquatic environments, surrounding the Great Lakes.

These parasites live inside the bird's oviduct, and grow to length of 7 to 9 mm (0.28 to 0.35 in). They can cause severe infections in hens, as they damage the bird's oviduct tissues which can result in inflammation, often leading to peritonitis and/or secondary invasion with bacteria that can worsen the infection. P. macrorchis produces small, oval eggs that are less than 15x25 micrometers.

Life cycle
P. macrorchis has a complex, indirect life cycle, which uses two intermediate hosts---the freshwater snail and dragonflies. Birds become infected by consuming both the contaminated dragonflies or snails.

Signs of infection include
  • Bright green colored droppings, which sometimes may contain flukes
  • Pasting (soiling) of vent feathers
  • Loss of appetite
  • Restlessness
  • Increased thirst
  • Difficulty breathing
  • Walk abnormally
  • Tense and hot abdomen

Treatment options
There are reports that praziquantel (5 to 10 mg/kg) and mebendazole (10 to 50 mg/kg) may be effective.


  • Order: Plagiorchiida
  • Family: Prosthogonimidae
  • Genus: Prosthogonimus


  • chickens
  • ducks
  • sparrows
  • crows

Associated Diseases