a genus of parasitic nematodes of the family Syngamidae. Syngamus infest the respiratory tract of birds. The males reach a length of 6 mm, and the females a length of 20 mm. The males are in a constant state of conjugation with the females. There are ten species, the most typical being S. trachea, which parasitizes chickens, turkeys, and many wild birds. The life cycle usually does not include an intermediate host, although it may include such reservoir hosts as earthworms, mol-lusks, and various insects. Syngamus cause gapeworm infection, which may result in the suffocation of birds, especially young individuals, if large numbers of the parasite are present. The infection is treated by introducing a weak aqueous solution of iodine with potassium iodide or sodium salicylate into the trachea of diseased animals.