Anatomical t'lianyes. Syiiiptoms. Diagnosis. 81 



and can get out only afteii the latter lias become torn or decom- 

 posed, either in the air passages of the host or after having 

 been coughed np into the outside world. In spite of the con- 

 tinuous copulation, the discharge of the ova is possible, accord- 

 ing to Railliet. In moist material, in water or in the air pas- 

 sages eel-shaped embryos are developed in from one to several 

 weeks. If ova or embryos are swallowed by fowl with food 

 or drink, they adhere, according to Walker, to the wall of the 

 esophagus or crop or they wander from there into the stom- 

 ach, to get into the kings and from there into the trachea, after 

 perforating the wall of the esophagus. 



Since it has been possible to produce the disease artificially 

 (Ehlers) by feeding embryos containing ova, it must be assumed 

 that the worm does not require an intermediary host for its 

 full development, and that hence ova liberated in the air pas- 

 sages may there go through all developmental stages. It is 

 therefore possible that the disease may be transferred directly 

 from sick to healthy birds, if the latter swallow the infected 

 secretion which the former have coughed up. Walker found em- 

 bryos of syngamus in infected neighborhoods in angleworms, 

 which undoubtedly ingested them with soil; hence fowl may 

 also infect themselves by the ingestion of angleworms. Klee 

 has shown that rooks which frequently harbor the parasite may 

 spreads the disease, as may also magpies and starlings. 



In a syngamus-enzootic among pigeons Rossi noticed a spread of the infection 

 to the young squabs by the mother's fee<ling them. The squabs succumlied to a 

 verminous inflammation of the crop. 



Anatomical Changes. The worms are generally found in 

 large numbers (30-40) in the air passages; Syngamus trache- 

 alis preferably in the trachea, Syngamus bronchialis deeper in 

 the bronchi. The mucosa to which the worms adhere shows ca- 

 tarrhal changes, also occasionally small abscesses ; the lungs are 

 frequently affected in Syngamus lironchialis infections. Both 

 species are not uncommonly found in the air vesicles. 



Symptoms. The sick birds begin to cough and they shake 

 their heads repeatedly; they expel masses of tenacious mucus 

 from the mouth. They often open their bills (hence the com- 

 mon English name of the disease ''gapes") and have a whistling 

 breath. Emaciation soon develops in spite of a good appetite. 

 The respiration becomes more and more difficult, abundant mu- 

 cus collects in the buccal cavity, the appetite gradually disap- 

 pears, the birds stand with ruffled feathers and they die totally 

 exhausted or even earlier during an attack of dyspnea. Older 

 birds sometimes recover if only few Avorms are present. 



Diagnosis. The disease can be diagnosticated upon detection 

 of the worms or ova coughed up with the secretion. The worms 

 may be seen in the trachea of larger birds on intense illumina- 



