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Chickens, turkeys, geese, guinea fowl, pheasants, peafowl and quail can all be infected. The organism is found in the trachea, bronchi and bronchioles.  

 

It is sometimes designated at "redworm" because of its colour or "forked worm", because the male and female are in permanent copulation so that they appear like the letter "Y". The life history of the gapeworm is peculiar in that transmission from bird to bird may be successfully accomplished either directly (by the feeding of embryonated eggs or infective larvae) or indirectly (by ingestion of earthworms containing free or encysted gapeworm larvae they had obtained by feeding on contaminated soil). Gapeworm larvae in the earthworm remain infective to young chickens for as long as 4 years. Slugs and snails may also serve as transfer or auxiliary hosts of larvae. S. trachea is the causative agent of "gapes" (laboured breathing due to parasites) in chickens, turkeys, peacocks and pheasants.

 

In the artificial rearing of pheasants, gapes are a serious menace. Confinement rearing of young birds has reduced the problem in chickens compared to a few years ago. However, this parasite continues to present an occasional problem with turkeys raised on range.

 

Young birds are most seriously affected with gapeworms. The rapidly growing worms soon obstruct the lumen of the trachea and cause suffocation. Turkey poults, baby chicks and pheasant chicks are most susceptible to infection. Turkey poults usually develop gapeworm signs earlier and begin to die sooner after infection than young chickens. Full-grown birds rarely show characteristic signs unless heavily infected.

Birds infected with gapeworms show signs of weakness and emaciation and usually spend much of their time with eyes closed and head drawn back against the body. From time to time they throw their heads forward and upward and open the mouth wide to draw in air. An infected bird may give its head a convulsive shake in an attempt to remove the obstruction from the trachea so that normal breathing may be resumed. Little or no food is eaten in the advance stages of infection, and death usually ensues.

Examination of the trachea of infection birds shows that the mucous membrane is extensively irritated and inflamed. Coughing is apparently the result of this irritation to the mucous lining. Lesions are usually found in the trachea of turkeys and pheasants but seldom if ever in the tracheas of young chickens and guinea fowl. These lesions or the male worm, which remains permanently attached to the tracheal wall throughout the duration of its life. The female worms apparently detach and reattach from time to time in order to obtain a more abundant supply of food.

Modern poultry practices, especially confinement rearing of broilers and pullets and caging of laying hens, have significantly influenced the quantity and variety of nematode infections in poultry.

 

For most nematodes, control measures consist of sanitation and breaking the life cycle rather than chemotherapy. Confinement rearing on litter largely prevents infections with nematodes using intermediate hosts such as earthworms or grasshoppers, which are not normally found in poultry houses. Conversely, nematodes with direct life cycles or those that utilise intermediate hosts such as beetles, which are common in poultry houses, may prosper. Treatment of the soil or litter to kill intermediate hosts may be beneficial. Insecticides suitable for litter treatment include carbaryl, tetrachlorvinphos (stirofos). However, treatment is usually done only between grow-outs. Extreme care should be taken to ensure that feed and water are not contaminated. Treatment of range soil to kill ova is only partially successful. Changing litter can reduce infections, but treating floors with oil is not very effective. After the old litter has been removed, spraying with permethrin or a mixture of Rabon and Vapona has proven effective for beetle control.

 

Raising different species or different ages of birds together or in close proximity is a dangerous procedure as regards parasitism. Adult turkeys, which are carriers of gapeworms, can transmit the disease to young chicks or pheasants, although older chickens are almost resistant to infection.

 

Syngamus approved compounds. Thiabendazole is currently approved for use only in pheasants at a level of 0.05% for 2 weeks and is effective when administered in the feed. Continuous medication of pen-reared birds has been recommended, but is not economical.

 

Several other compounds have been shown effective against Syngamus under experimental conditions. Methyl 5-benzoyl-2-benzimidazole was 100%efficacious when fed prophylactically at 0.0064% and curatively at 0.0125% to turkey poults. A level of 0.044% for 14 days has also been effective.

 

5-isopropoxycarbonylamino-2-(4-thizolyl)-benzimidazole was found to be more efficacious than thiabendazole or disophenol (2, 6-diiodo-4-nitrophenol). The level of control with three treatments of cambendazole* on days 3-4, 6-7, and 16-17 post-infection was 94.9% in chickens (2mg/kg x 50mg/kg) and 99.1% in turkeys (2mg/kg x 20mg/kg).

 

Levamisole*, fed at a level of 0.04% for 2 days or 2 g/gal drinking water for 1 day each month, has proven effective in game birds. Fenbendazole at 20 mg/kg for 3-4 days is also effective.

 

*Not approved for use in commercial poultry.