THE DUCK RTCKNESS IN UTAH. 13 



UNTENABLE THEORIES ADVANCED. 



Interest in the duck sickness has been so great among sporl cm □ 

 and others that many theories as to its cause have beer propounded. 

 One of the first and most important attributed it to a disease of 

 bacterial or protozoan origin. A few birds examined early in the 



outbreak revealed many coccidia, and for a time these; were considered 

 the causative agents of the disease. Later investigations, however, 

 did not support this, and all efforts to find and isolate an organism 

 capable of transmitting the trouble from one bird to another failed. 

 For a brief account of the investigations made by the Bureau of 

 Animal Industry the reader is referred to the preliminary report. 1 



Superficially the duck sickness presents many resemblance i to 

 avian cholera. Examination of many hundreds of specimens by 

 the writer failed, however, to show any lesions whatever in the 

 viscera (except the irritation in the intestine that has been described). 

 Many blood smears were examined from the peripheral circulation 

 and the heart, with no result. In addition, a large number of experi- 

 ments were made in attempting to transmit the trouble. Healthy 

 birds were confined with sick birds or were given grain treated freshly 

 with feces taken from affected individuals. Some were fed forcibly 

 on fragments of organs or the entire stomach and intestinal content 

 of sick birds. The mucous lachrymal discharge in birds far gone 

 was transmitted to the eyes of some. Intravenous and hypodermic 

 transfusions of blood were made. All these experiments gave 

 negative results. It has been said that domestic fowls are very 

 susceptible to the duck sickness. Attempts to transmit the trouble 

 to hens were without effect. 



During three field seasons many hundreds of wild ducks were 

 kept in confinement. After the nature of the trouble was under- 

 stood (in 1914) healthy and sick birds were confined in the same 

 pens continually, with no attempt to avoid possible transmission 

 of the trouble, and in no instance did any of the normal birds contract 

 the sickness. Sick birds were handled constantly by the writer 

 and his assistants, but in no case did ducks or other birds tamed and 

 kept as pets around the laboratory contract the trouble. A young 

 great blue heron, reared by hand in 1916, was, with no ill effect, 

 fed often on the flesh of birds that had died from the. duck sickness. 

 This same year a considerable number of yoimg wild ducks were 

 reared for use in experiments. Once or twice a week these birds 

 were fed a bran mash containing a quantity of meat. TThen fresh 

 fish were not available, the bodies of ducks and other birds newly 

 dead from the duck sickness were ground up and fed to them, with 

 no harmful result. If the sickness had been contagious or infectious, 

 cases would have resulted under such treatment. 



iU.S Dept.Agr., Bui. 217, p. 5, 1915. 



