WESTERN DUCK SICKNESS 45 



WESTERN DUCK SICKNESS A FORM OF BOTULISM 



In 1910, the tremendous mortality among ducks and other birds 

 in the vicinity of Great Salt Lake, Utah, first attracted continent-wide 

 attention, when tens of thousand of ducks were found dead in this re- 

 gion. The sickness continued to take its toll in succeeding years, and 

 there has been a notable increase in the number of points of outbreak. 

 Distribution of the disease conforms in general to the region of alkaline 

 waters and soils of the Western States and the southern part of the 

 Western Canadian Provinces. 



The disease, though varying in intensity from year to year, is con- 

 sidered to be the greatest drain upon western waterfowl due to any 

 single natural agency. 



Some idea of the extent of the ravages of the disease is given by 

 Kalmbach and Gunderson (1934) who, speaking of one district only, 

 say: "Estimates of dead ranging from less than 100,000 to more than 

 300,000 made at Great Salt Lake in August, 1929, give a general idea of 

 the severity of the epizootic in that year .... in 1932, an estimate was 

 made of the number of dead on the south shore of Willard Spur. Sec- 

 tions of the shore line 100 yards in length were taken as units and the 

 readily visible dead counted. For a distance of 6 to 8 miles dead ducks 

 were scattered on the flat terrain in numbers ranging from 8,000 to 

 10,000 to the mile. It was estimated that there were 150,000 dead on the 

 south shore of Willard Spur and the adjacent Bear River Bay. Many 

 more thousands lay scattered on the east, north, and west shores, and 

 an indeterminate number were hidden in the vegetation of the Bear 

 River Migratory Bird Refuge or obliterated on the mud flats. It was es- 

 timated that fully a quarter of a million water-fowl perished from duck 

 sickness in this general area during 1932." 



In early stages of the investigations of the disease it was thought 

 that the sickness was due to toxic action of certain soluble salts found in 

 alkali. It has now been established, however, that the malady is a form 

 of botulism, caused by a bacterium, Clostridium botulinum, type C. 



This organism thrives under conditions of decay of dead organic 

 matter, animal or vegetable, in an alkali environment; shallow, stag- 

 nant water and hot weather are factors that greatly favour development 

 of these conditions of decay. The disease is, in effect, a form of food 

 poisoning. No instance of human beings contracting botulism through 

 eating the flesh of infected birds is known. 



In summarizing remedial measures which might be applied, Kalm- 

 bach and Gunderson (1934) suggest that lasting and effective means of 

 prevention of the disease lie in modifying or eliminating the conditions 

 that favour the development of the organism. By flooding mud flats and 

 shallow, stagnant water areas with deep or flowing water, temperatures 

 are reduced and, through a process of dilution, the poison may be re- 

 duced to the point of harinlessness. The expedient of temporarily cutting 

 off all water from infected areas has also been used effectively where the 



