\C)>< I'dn.TKV DISKASKS AM) TIIKIK TKKAT.M KNT. 



The presence of the worms causes an irritation and inflamma- 

 tion of till' nKiuhrane and stimulates the secretion of mucus. 

 Some (if the accumulation of worms and mucus Is expelled by 

 couj,diing. Sometimes jiart of it is swallowed and expelled with 

 the feces. The loosened material may be drawn into the deeper 

 air passages during inspiration. Death may occur from suffo- 

 cation i\ue to the obstruction of the air passages with worms and 

 mucus, or weak individuals may die fn^m loss of blood. 



Etiology. The only cause of the disease is the nematode or 

 thread worm Syngamus traclicalis Siebold, called the gape worm, 

 red worm, or forked worm. ( See figs. 47 to 49). These para- 

 sites obtain their nourishment by sucking the blood from the 

 mucous membrane of the trachea. They are attached in pairs 

 to the membrane by their sucker-like mouths. Beside bringing 

 about a considerable loss of blood the worms cause irritation and 

 inflari'iiation of the membrane and a copious secretion of mucus. 

 The Ivvo sexes are .so closely attached to each other that they 

 can not l)e separated without tearing. The body of an adult 

 female is swollen with thousands of eggs and occasionally con- 

 tains some embryos. The eggs are not laid but escape when the 

 Ixidy of tlie female is ruptured. This may take place with the 

 decomposition of tlie worm or the body may be torn In- the 

 coughing of the bird. The eggs may develop and grow to 

 adult worms within the trachea of the same bird. The worms. 

 cgg^ and embryos are often coughed up. Sometimes they are 

 swallowed and then some of the eggs and embryos may be passed 

 with the feces. Tlie worms coughed up are eagerly eaten by 

 the same or other birds and the ova and embryos are often taken 

 with contaminated food and (h-ink. Developing embryos have 

 been found in earth wcirnis living in infected -poultry yards, 

 and tliese will cause gapes if fed to chicks. 



The eggs and embryos need only warmth and moisture to 

 develop. Eggs may develop in the digestive organs. It is not 

 known hf)w the embryos reach the trachea from the digestive 

 organs. A large number of those eaten never reach the tra- 

 chea but are either digested or voided with the feces. Salmon 

 says : "Although there are some thousands of eggs in the adult 

 worms. 10 to 15 worms liave l)een fed to a single chicken, and, 

 as a result, not over 4 or 5 embryos would reach and develop 

 in the trachea." According to Theobald. Elder found copulated 

 worms where several of the females were full of worms 10 days 



