• • • " , 

 .• • •. 



• • • 



It is quite possible to have the disease develop in the eyes 

 by the infection gaining entrance, and the bird irritating the 

 membranes by rubbing them against objects or by scratching 

 them with their feet. 



The disease is frequently spread by food or drink which is 

 contaminated with infective material. 



A very common source of the disease is the poultry show 

 where infected birds are exhibited, and conditions exist favor- 

 able to reduce the bird's resistance. It very frequently happens 

 that on the return of birds from the show the disease develops 

 in the course of a week or ten days. Sparrows and pigeons are 

 common carriers often transporting the infection great dis- 

 tances. This is a very important method of transmission 

 often overlooked. The disease has been observed in sparrows 

 in a number of cases and exhibiting in them the same charac- 

 teristics as in other birds. Sparrows and pigeons come in direct 

 contact with poultry at feeding time and thus infect them. It 

 is sometimes spread by such intermediary agents as infected 

 coops, clothing, etc. Young birds are more susceptible to the 

 infection than older ones. Pigeons and chickens seem to be 

 far more susceptible than other birds. 



It has been observed that one attack of the disease will pro- 

 duce immunity for a certain period. Either the skin form or 

 involvement of the mucous membranes confers equal immunity 

 against the opposite form. 



Pathology 



The post-mortem findings vary with the immediate cause of 

 death. In rare cases when death is due to suffocation early in 

 the disease only the acute conditions are noted. The body ap- 

 pears fairly well nourished, the mucous membranes are covered 

 with a thick slimy mucous which may occlude the upper air 

 passages. In the larynx, or somewhere along the trachea, pos- 

 sibly in the larger bronchi, will be found the mass of dense, 

 tough, yellowish material obstructing the lumen. 



In some cases when both eyes are involved death results 

 from starvation early in the disease. The body is emaciated. 

 The mucous membrane of the eyes, and often of the mouth 

 and respiratory passages show inflammation, and usually there 

 is a mass of this same yellow material in the conjunctival sac 

 distorting or obscuring the eyes. The skin around the eyelids 

 may also be involved. 



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