Syngamus (Gape Worm)

Syngamus

Only one member of this genus, Syngamus trachea, is of veterinary significance and parasitizes the upper respiratory tract of non-aquatic birds; it is commonly known as the 'gapeworm' and may be responsible for respiratory distress and death.

Major Specie	Host	Location/Site	Distribution
Syngamus trachea (Gape worm)	Domestic fowl and game birds such as pheasants and partridge	Trachea.	World wide

Identification

Gross:

• The reddish worms, large female (up to 2.0 cm) and small male (up to 0.5 cm), are permanently in copula forming a Y shape: they are the only parasites found in the trachea of domestic birds.

Microscopic:

• The worms have large shallow buccal capsules which have up to ten teeth at their base.

Epidemiology

• Gapeworm infection primarily affects young birds, but turkeys of all ages are susceptible,
• Disease is seen most fre­quently in breeding and rearing establishments where outdoor pens, such as are used for breeding pheasants, are in use. Infection may be initiated by eggs, passed by wild birds such as rooks and blackbirds; these may also infect earthworms.the adults often acting as carriers.
• Eggs may survive for up to nine months in soil
• L₃ for years within the earthworm or other transport hosts.

Life Cycle

Adult male and female are found incoupulob in trachea or bronchi

 

Eggs are laid in the trachea and then swallowed and passed in the faces. L₃ develops within the egg.

F/H becomes infected firstly by ingestion of the L₃ in the egg, by ingestion of the hatched L3 or thirdly by ingestion of a transport host (earth worm, slugs, snails and beetles) containing the L₃

After penetrating the intestine, the L₃ travel to the lungs, (4-6 hrs in experimental infection)

The two parasitic moults (L₃ to L₄ to L₅) take place in the lungs within five days by which time the parasites are 1.0-2.0 mm long

Copulation occurs around day seven in the trachea or bronchi after which the female grows rapidly.

PPP: 18-20 days.

Pathogenesis:

• The effects of S. trachea are most severe in young birds especially game chicks and turkey poults. In these, migration through the lungs in heavy infections may result in pneumonia and death. In less severe infec­tions the adult worms cause a haemorrhagic tracheitis with excess mucus production which leads to partial occlusion of the airways and difficulty in respiration.

Clinical Signs:

• Pneumonia during the prepatent phase may cause signs of dyspnoea and depression,
•    the pres­ence of adult worms and excess mucus in the trachea lead to signs of asphyxia or suffocation with the bird gasping for air; often there is a great deal of head shaking and coughing as it tries to rid itself of the obstruction. The clinical picture of 'gapes' may thus range from gasping, dyspnoea and death to, in less severely affected animals, weakness, anaemia and emaciation.

Diagnosis:

• Clinical History with epidemiology
• Clinical signs
• Coproscopy: :
• The ellipsoidal egg of S. trachea has an operculum at both ends.
•  
• PM findings: worms will be found attached to the tracheal mucosa.  

Treatment:

• In-feed thiabendazole and fenbendazole are effective, administered usually over periods of 3-14 days.
•  Nitroxynil and levamisole are also very efficacious when given in the water.

Control:

·         Young birds should not be reared with adults, espe­cially turkeys,

·         Runs or yards should be kept dry and contact with wild birds prevented.

·         Drug prophylaxis may be practised over the period when outbreaks are normally expected.