Gapeworm infection in poultry their prevention and control

Alok Kumar Singh^1#, Deepali Tiwari² Pradeep Kumar³and N. D. Hirani⁴

¹Department of Veterinary Parasitology, College of Veterinary Science & A.H., Rewa

²B.V. Sc & A.H., Student, College of Veterinary Science & A.H., Rewa

³Department of Veterinary Parasitology, DUVASU, Mathura

⁴Department of Veterinary Parasitology, COVSc &A. H., Kamdhenu University, Junagadh

^#corresponding author- email: alok122@gmail.com

Gapeworms i.e. Syngamus trachea are classified within nematodes that affects the ‘respiratory system’ of birds as the adult worms reside in the trachea (or windpipe) and due to its lodgement, it often produces a gurgling sound or ‘tracheal rattle’ that may be confused with respiratory problems. Gapeworm is commonly found in poultry birds common in pheasants, but it also affects chickens, guinea fowl, and turkeys. The presence of gapeworms can result in considerable losses in pheasants and turkeys. The most notable sign of gapeworm infection is gasping in birds for air, often referred to as ‘gaping’. Furthermore, head shaking and neck stretching are commonly observed for proper air passage. When birds are held, a gurgling sound can frequently be heard, which indicates a ‘tracheal rattle’. The gasping for air associated with gapeworms is often misdiagnosed as another respiratory issue. In severe cases of infestation, suffocation may lead to death as gaseous exchange insufficiency occurs.

Gapeworm infestation can occur directly when birds consume eggs that have been either ingested or expelled by infected birds, or by consuming infected feed and water also indirectly through intermediate hosts such as earthworms or snails. Young birds, particularly those under 8 weeks of age, are particularly more susceptible to gapeworm. Gapeworms generally inhabit the trachea (windpipe) but may also be found in the bronchi and lungs. Typically, eggs are gathered from the ground or from intermediate hosts like earthworms or snails. The eggs hatch, allowing the larvae to penetrate the intestinal walls and migrate to the lungs and bronchi of young birds. It is at this point that they undergo a larval moult before moving up to the trachea. Once they arrive at this site, male and female gapeworms attach to one another these are y shape in together where male worm anchors female worm . This entire process takes about 7 days. When fully matured, they display a ‘Y’ shape and measure between 1 to 2 cm in length. Gapeworms release eggs that are either coughed up onto the ground or swallowed and later excreted in the faeces. The gapeworm, scientifically referred to as Syngamus trachea, is a parasitic nematode that resides in the trachea of both domestic and wild birds worldwide.

Life Cycle:

Chickens become infected with S. trachea by inadvertently consuming larvae that have contaminated the surrounding environment, feed, or water by faeces from an infected bird. Numerous wild bird species can harbour S. trachea, shedding the larvae in their droppings. Chickens may also become infected indirectly by ingesting earthworms, snails, or slugs that carry the infection. Regardless of the method of infection, once chickens ingest the larvae, these will migrate through the gastrointestinal tract until they reach the trachea, where they reproduce, lay eggs, feed on blood, and reside. The eggs may either be coughed up or swallowed by the chicken. If swallowed, they will be excreted with the faeces, further contaminating the environment with additional eggs for other flock members or even for the same bird to ingest, leading to an accumulation of more worms or the infection of others. The prepatent period lasts between 17 to 20 days.

Clinical Signs:

Affected chickens are frequently seen stretching their necks, opening their mouths, and gasping or gaping for air. This gaping occurs due to the presence of multiple worms in the trachea, resulting in a partial to complete obstruction of airflow. Without treatment, heavily infested birds often succumb to suffocation. Smaller chicken breeds, such as bantams and younger chickens, are more severely impacted by gapeworms. This is associated with the size of the chicken’s trachea; when there is a larger space available for the worms to attach, they are less likely to cause a blockage that prevents the chicken from breathing and death. The signs are yawning, gurgling or respiratory distress, loss of appetite, and ultimately coughing and choking, along with head shaking, decreased feed intake, and an unthrifty appearance also observed. Affected areas include the trachea (windpipe), bronchi, and lungs.

Transmission:

• It occurs through intermediate hosts such as earthworms or snails, as well as directly by birds that consume eggs that have been coughed up or excreted in faeces. Intermediate host present in environment ingest infected eggs and during feeding by birds it gets entered into GI tract of susceptible host causing infection.

Other names:

• Gapes, red worms, forked worms, Y worms, or gape Worm.

Diagnosis includes:

• History – it includes queries of general health of birds and presence of intermediate host and environmental analysis of sustainability of worm, feeding and watering pattern in farm and precautionary measure adapted for prevention.
•  Clinical signs – gasping is common sign in birds which indicate respiratory distress, gurgling sound, respiratory rattle, head stretching etc is commonly observed.
•  Physical examination – presence of worms and common sign of respiratory stress.
• Faecal flotation method (to detect eggs in faeces) of infected birds
• Identification of worms in the trachea during postmortem examination.

Treatment:

• Albendazole is administered orally to each bird, with a repeat dosage after 2 weeks.
• Safeguard 10% Liquid Dewormer, such as Fenbendazole, is used off-label in poultry. It should be introduced into the flock’s drinking water at a dosage of 3 mL per gallon for a period of 3 days, with a repeat every 3 weeks.
• 1% Ivermectin Injectable is also applied off-label in poultry. This medication can be given orally to each chicken or mixed into the flock’s water supply. For oral administration, the dosage is 0.25 mL for large chickens and 0.1 mL for bantams. If mixed in water, the dosage is 4 mL per gallon. Fresh preparation is required daily for 2 days.
• Pour-on Ivermectin (5 mg/mL) is utilized off-label in poultry. It is intended solely for external use and should not be administered internally to the birds. Apply it topically to each chicken using an eye dropper on the skin at the back of the neck. Bantams should receive 3 drops, standard-sized birds 4-5 drops, and large breeds 6 drops. This should be repeated in 2 weeks.
• Levamisole Soluble Drench Powder is also used off-label in poultry. It is added to the flock’s water supply. It is crucial to note that severely weakened chickens should not receive this medication, as it may impair their ability to fight infections. Administer at a rate of 10 mL per gallon of water for only 1 day, with a repeat in 7 days, and again 7 days thereafter.

Prevention and control:

• Tilling the soil in the pens at the conclusion of the growing season aids in diminishing residual infections.
• Treating the soil to eradicate earthworms, snails, and slugs.
• Rotating the areas designated for poultry confinement.
• Implementing an effective worming strategy, rotating grazing areas, and avoiding contact with ground frequented by wild pheasants.
• The bird should be separated from turkeys who play a symptomless carrier for infection.
• Rearing under moist ground should be avoiding, regular removal of faeces and sanitation is essential.
• Isolation and segregation of newly introduced bird in the flock.
• Sick bird should be treated with suitable drugs and kept in another shed.
• Young birds should be separated from adult birds such as turkey to prevent cross contamination.
• Practice bio security measure by keeping poultry yard and farm clean, dry, prevent entry of wild birds and intermediate host to break lifecycle transmission.
• Avoid overcrowding in birds as respiratory transmission can cause large birds’ mortality.
• Proper monitoring, bio security measure, sanitation and effective treatment is sufficient to control gapeworm infection in birds and minimal economic loss in farm.