Some recent observations on the gapeworm (Syngamus trachea) in pheasants.

Abstract

The nematode parasite causing the 'disease' known as gapes in poultry and game birds, Syngamus  trachea, has in the past been the subject of intense study and inquiry. Notable work in previous years has been recorded by such authors as Clapham, Olivier, Ortlepp and Taylor. Recently, however, little has been published about this parasite whose life history and biology must be one of the most intriguing and complex to appreciate. The reason for decline in attention is obvious. The parasite has ceased to be an economic problem in the poultry industry in recent times due to the profound changes in the method of breeding and rearing of chicken and turkeys. Modern methods of poultry management make it impossible for the animals to even see soil and grass let alone pick up parasitic infections from them. As often happens, the amount of attention and study a parasite receives declines as sharply as its economic importance diminishes. Syngamus is still, however, an important source of losses to rearers of pheasants and partridges not only in this country but throughout the world. It was for this reason that the Game Research Association decided to make this parasite the subject of one of its investigations and to attempt to appreciate the significance of the organism by research into basic life history and biology principles. At the same time new drugs are being tested for efficiency in control.

The life history of the parasite was first described by Ortlepp (1923) who gave detailed information on the egg development and life cycle of the worms found in the trachea of chicken. Much of the research on this parasite in pheasants was performed by Clapham and this author's vast output of literature included further contributions of knowledge of the life cycle especially concerning vector hosts (1934, 1935a, 1939a, 1939b), and possible cures (1935b, 1950a, 1950b). Madsen (1952) gives a very comprehensive survey of the, occurrence of Syngamus and other nematode parasites of game birds. Olivier (1942, 1944) published information on possible acquired immunity of pheasants to Syngamus. Taylor (1935, 1938) produced information on the longevity of the infective stages of the gapeworm in its vector hosts. So far, however, little is known of the distribution of reservoirs of infection, especially during the winter months when birds harbouring the parasites never seem to be seen in the wild. Little is also known of the range of invertebrates that can act as vectors for the worm; of which of these vectors are the most important; whether different vectors are important in carrying over the infection in different regions; or of the effects of different soils, if any, (whether directly, or indirectly by affecting the vectors). Until now, no effective anthelmintic treatment for the parasite has been available.