Gapeworm infection (a common name for syngamiasis) is a parasitic disease caused by the common nematode parasite,Syngamus trachea
(otherwise known as the gapeworm). S. trachea
attach themselves within the duck's trachea, where they feed on their blood and reproduce.
The severity of the infection depends on the duck's age and size, and number of S. trachea
present in the trachea. Younger ducks and smaller duck breeds are usually more severely affected then large duck breeds and older, adult ducks. This is related to them having a more narrower tracheal opening---meaning a smaller number of S. trachea
can be present and still cause the duck to suffocate.
The presence of S. trachea
in the duck's trachea causes clinical signs related to mild to extensive blocking of airflow. Ducks are most commonly seen:
- 'Snicking', whihch is a combination of sneezing, coughing, and sideways flicking of their heads.
- Gasping or 'gaping', in which they are seen extending their necks outward and gasping for breath through their opened bills.
- Some may produce a hissing noise at the same time.
How Ducks are Infected
can have a direct or indirect life cycle. Direct meaning that it reinfects the hosts themselves (other ducks, poultry, and even wild birds), and indirect meaning it can also be found within certain mollusc species (slugs, snails, and earthworms). Ducks become infected either by consuming one of the species of mollusc containing S. trachea
, or by ingesting their eggs from the environment when an infected bird has coughed them up. 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.