Page:Popular Science Monthly Volume 77.djvu/193

Rh In the warfare against the ravages of disease a most rational hygiene of the poultry yards must be observed, and in order to understand thoroughly those factors which have to do primarily with eliminating 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 ascertained 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 particular 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 measures involve too much time, but under many circumstances and especially at this infant stage in our knowledge concerning avian diseases the application of searching and delicate parasitological and bacteriological 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, states that this coccidium may infect turkeys, ducks and pigeons. It has a definite 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 permanent 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