Pulmonary parasitism of fowls and animals by a nematode of the closely related genera Cyathostoma and Syngamus is not uncommon. The best known species of these genera is Syngamus trachealis, which causes gapeworm disease of domestic pheasants and chickens. This parasite invades the trachea and bronchi and causes a peculiar stretching of the neck accompanied by a yawnlike opening of the beak; sometimes the worms are expelled in a tenacious mass of mucus. If the infestation is extreme, death may be caused by exhaustion or, less often, by asphyxiation.
According to the available literature, infestation of man by Cyathostoma has not been reported. A pair of forked worms recovered from the sputum of a woman residing in St. Lucia, West Indies, were figured and described by Leiper1 as a new species of the genus Syngamus. The animal host of this nematode has not been found; furthermore, a report of
JOHN JHS, SIMMONS JS, GARDNER LL. INFESTATION OF THE LUNG BY A NEMATODE OF THE GENUS CYATHOSTOMA. JAMA. 1929;92(22):1816–1818. doi:10.1001/jama.1929.02700480006003