OUTBREAKS SINCE 1932 
The foregoing are just a few of the high lights in the story of 
"botulism manifested "before its cause Was discovered and "before information 
regarding its history and range was compiled (l). The most important out- 
breaks occurring within the past 5 years (1933-37) are discussed in the fol- 
lowing paragraphs. It must be explained, however, that definite bacteriolog- 
ical proof of the presence of this disease is rarely available. When such a 
diagnosis is lacking, records have been included on the ba.sis of symptoms 
noted, the course of the epizootic, and the nature of environmental condi- 
tions. 
It is emphasized, furthermore, that the reported outbreaks doubtless 
constitute only a fraction of those that actually occur. The more disas- 
trous ones and those that appear in frequented areas are likely to be re- 
corded, but many minor on; a may be in inaccessible areas, and these, in the 
aggregate^ may account, fpr^a^ignif i cant total of dead birds. Hence this 
presentation does not purport to be a comprehensive summary of the outbreaks 
of avian botulism that have occurred during the period indicated. 
In the United St ates 
In the United States, botulism among wild birds during the past 5 
years has appeared in what might be termed normal frequency . and intensity 
as judged by the history of the malady daring the past quarter of a cen- 
tury. Although there have been no outbreaks of mammoth proportions com- 
parable with that of 1910, mortality has been severe, and the disease has 
appeared in an increasing number of localities. The latter circumstance 
is of particular significance, since it may be indicative of a spread of 
the organism and the malady or an increase in the prevalence of conditions 
conducive to it. 
In the Bear River section of Great Salt Lake, Utah, one of the old- 
est known points of infection, conditions in 1933, 1934, and 1935 showed 
improvement over those prevailing when the disastrous outbreak of 1932 oc- 
curred (see page 2). Although several thousand dead were found there dur- 
ing each of the 3 years, this number reflected a relatively favorable con- 
dition in this highly infected area, particularly in view of the fact that 
extremely low water prevailed. In 1936 mortality increased, and a con- 
servative estimate of the losses placed the total number of waterfowl 
succumbing to botulism in the Salt Lake Valley at 50,000, about a fifth of 
the toll of 1932. Birds died not only on the deltas of all three rivers 
flowing into Great Salt Lake— the Jordan, the : : iear, and the Weber — but many 
thousands perished at other points in the valley even as far south as Utah 
Lake, which, from experiences of earlier years, had become known as a point 
of infection. 
In 1936 the Biological Survey and the Utah State Game and Fish De- 
partment cooperated in an extensive program of salvaging disabled birds 
and frightening healthy ones from infected areas. In 1937 the disease 
again appeared in marked intensity at the northern end of Great Salt Lake, 
