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Gapeworms Overview

Gapeworm, Syngamus trachea, is a parasitic nematode worm found in the trachea of domestic and wild birds worldwide. S. trachea attach themselves to the bird's tracheal wall where they feed on blood, resulting in the development of lymphoid nodules, hemorrhagic tracheitis, bronchitis, and eventually asphyxiation. Female S. trachea lay their eggs in the bird's trachea, which hatch and are either coughed up or swallowed by the bird, later defecated out into the environment.

Infection with S. trachea often causes respiratory distress, resulting in the birds gasping or 'gaping'. The gaping is caused by the worm's blocking airflow into the bird's airway. Ducks are often seen stretching out their necks, opening their mouths and gasp for air producing a hissing noise as they do so. Without treatment, if birds are heavily infested they often die from suffocation.

Adult birds are usually not as severely affected as younger, smaller ducklings. The severity depends on the degree of infection and size of the bird. Smaller birds are more severely affected due to the narrower size of their tracheal opening.

S. trachea are transmitted to poultry orally through ingestion of the tiny parasitic eggs in infected bird's feces or through consuming earthworms, that are often infected with S. trachea. Wild birds often act as reservoirs of S. trachea--pheasants, ruffed grouse, partridges, wild turkeys, magpies, meadowlarks, robins, grackles, jays, jackdaws, rooks, starlings and crows.


Emitting a grunting sound
Difficulty breathing
Head shaking
Reduced feed intake
Unthrifty appearance


  • History
  • Clinical signs
  • Physical exam
  • Fecal exam


MethodMethod Summary
Fenbendazole5-20 mg/kg of body weight, administered orally, once a day for 5 days
Thiabendazole100 mg/kg of body weight, administered by mouth SID for 7-10 days


  • Tilling the soil in the pens at the end of the growing season helps to reduce the residual infection.
  • Treating the soil to eliminate earthworms, snails and slugs
  • Administering a wormer at 15 to 30-day intervals
  • Including a drug at low levels continuously beginning 15 days after birds are placed in the infected pens



Risk Factors

  • Crowding of birds
  • Unsanitary living conditions