THE DUCK SICKNESS IN UTAH. 13 
UNTENABLE THEORIES ADVANCED. 
Interest in the duck sickness has been so great among sportsmen 
and others that many theories as to its cause have been 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 resemblances 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 young 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. When 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. 
1U.S Dept.Agr., Bui. 217, p. 5, 1915. 
