Gapes - the disease and a review of recent methods of treatment.
Syngamus trachea, the 'gapeworm, has long been known in birds and was first described in the early 19th century by Montagu (1811). The respiratory disease caused by this nematode, or parasitic worm, is commonly known as 'gapes', from the sign of gaping, but the pathologist and veterinarian also know it as 'syngamiasis'. The gapeworm is most often found in the Galliformes but also in the Passeriformes, including such common hosts as Corpus frugilegus, the rook, C. corone, the carrion crow, C. monedula, the jackdaw, and Sturnus vulgaris, the starling.
Gapes will kill a bird when the infestation is very severe or if the windpipe becomes blocked, but equally the condition of affected birds may deteriorate sufficiently to increase the chance of trouble from other causes. It is, perhaps, one of the easiest diseases to identify. A sick bird breathes deeply and stands gaping, but in addition it will periodically cough and flick its open bill sideways as if attempting to physically dislodge the worms from its trachea or windpipe. This characteristic movement is known as 'snicking'.
The following review describes the life-cycle of the gapeworm and the various methods used over the years to deal with it, especially drug treatment. Aspects of diagnosis and husbandry are included in a paper by Howman (1979) and a general background to parasitic and other diseases in gamebirds and wildfowl is provided by Anon (1974) and Beer (1977).