AVIAN DISEASES 187 



In the warfare against the ravages of disease a most rational 

 hygiene of the poultry yards must be observed, and in order to under- 

 stand thoroughly those factors which have to do primarily with elim- 

 inating the trouble, it is to the use of disinfectants and antiseptics that 

 we must resort. Here again the science of bacteriology lends a helping 

 hand, for data concerning the efficiency of disinfectants can be ascer- 

 tained only by bacteriological technique. It then becomes the duty of 

 the scientist to direct his entire attention to those factors which in 

 themselves are sufficient to allow a foothold for many an infectious 

 disease. It is no less a fact among domestic birds than with human 

 beings, that infection may take place by contaminated food, the par- 

 ticular parasite or organism being transmitted in such manner. All 

 the modes of spread are recognized, and just as the spread of human 

 diseases are held to be matters of public concern and preventive measures 

 are instituted by expert bacteriologists, so also should the spread of 

 diseases among domestic fowls be of the same great concern to the 

 poultryman if he is desirous of maintaining his birds in a healthy 

 condition. 



Probably one of the most difficult problems in relation to avian 

 diseases lies in the prompt recognition of the cause, so that measures 

 may be employed immediately to allay the trouble. With the large 

 poultry farms it may appear that careful observation of hygienic meas- 

 ures involve too much time, but under many circumstances and espe- 

 cially at this infant stage in our knowledge concerning avian diseases 

 the application of searching and delicate parasitological and bac- 

 teriological tests are often necessary to determine the proper method 

 of procedure. 



The great losses to poultrymen from the disease known as "black 

 head " or " coccidiosis of turkeys " has called scientific men to make 

 thorough investigation and a specific parasite known as a coccidium 

 has been claimed to be the cause. Dr. Geo. B. Morse, of the Bureau of 

 Animal Industry, United States Department of Agriculture, 1 states that 

 this coccidium may infect turkeys, ducks and pigeons. It has a defi- 

 nite life cycle. He describes it as a certain circular, sometimes slightly 

 oval, cyst, 12 to 25 microns in diameter, containing granular matter 

 which may fill the cyst or occupy only a portion of it. These are per- 

 manent cysts and may be voided in the feces of the bird. These only 

 require warmth and moisture for their development into sporozoites by 

 which the disease is transmitted to other birds. By the destruction of 

 the malarial parasite within the body of man y we may break the life 

 cycle and thus interrupt the continuity of the transfer between man and 

 mosquito in the transmission of this disease. In like manner, the 

 scientist can plan to break the cycle of these avian parasites within the 



1 Circular 128 (1908), Bureau of Animal Industry, Dept. of Agriculture. 



