Visual display of the Aldo Leopold papers : 9/25/10-4 : Species and Subjects

Jan. 128. 
The disease "tularemia" has assumed such proportions in the 
United States that it appears desirable that the Biological Survey 
issue a statement summarizing the available information and the 
procedure that may be recommended by field representatives of the 
Bureau in their work with the public. The information here pre- 
sented has been endorsed by the Surgeon General of the United States 
Public Health Service, and the recommendations made are concurred 
in by him. 
Tularemia is a plague-like disease of rodents transmissible 
to man, It was originally discovered in ground squirrels in Calif- 
ornia in 1910 by Dr. G. W. McCoy, of the United States Public 
Health Service. Later (1919) it was found in jack rabbits in Utah, 
in the work of Dr. Edward Francis and his assistants of the Public 
Health Service, and was definitely established as the debilitating, 
disabling, and frequently fatal disease locally known as "deer- 
fly fever," which was affecting residents and visitors locally in 
certain country districts in jtah. Of 500 human cases reported in 
the United States, 20 have terminated in death. 
Positive diagnosis of the disease, isolation of the causa- 
tive organism Bacterium tularense, and development of a successful 
cultural technique were important steps in the history of tularemia 
and of investigations of wild animals as carriers of this disease. 
Later work has disclosed human cases of the disease in all States 
except Washington, Wisconsin, New York, Delaware, and the New 
England States, twenty-five States having been added to the list 
in the two years 1925 and 1926, and four in 1927. The disease has 
also been definitely established as identical with the rabbit- 
borne disease in Japan, known as Ohara's disease, which affects 
people there. 
Discovery of tularemia has cleared up many puzzling cases 
of illness that in the past have doubtless been wrongly diagnosed 
as "flu," septic infection, blood poisoning, or other kindred dis-

eases, because of a superficial resemblance of the symptoms at some 
stage of the disease. Human cases have been traced to rabbits 
or other animals in the locality or to shipments of diseased ani- 
mals sold in the public markets. This specific knowledge lays the 
foundation for intelligent action in maintaining essential safe- 
guards and in protecting the ptblic in the use of important game 

Among game animals tularemia occurs in nature in jack rab- 
bits, snowshoe rabbits, and cottontail rabbits, and is responsible 
for some of the periodic epizootics that kill them off locally in 
great numbers. This provides a reservoir for infection of both 
wild animals and human beings. In the Western States the disease 
is carried from animal to animal and to man by the bites of infect- 
ed deer flies and ticks, and ticks  also transmit the infection to 
man in the Southern States. Ticks carry the infection through the 
winter, and the females transmit it through the eggs to the next 
generation. Man also becomes infected by handling rabbit carcas- 
ses, as in dressing them for the table or cutting them up for such 
purposes as feed for dogs, hogs, foxes, or chickens, or as bait 
for fish or such carnivorous animals as coyotes. In the Eastern 
States direct contact in dressing the carcasses is the common means 
of infection. 
Tularemia is likely to manifest itself first by pain, ten- 
derness, and swelling of lymph glands draining the region where the 
infection occurs, as those of the elbow or armpit when infection 
has occurred on the finger. These symptoms will probably occur 
withii two to five days after infection, An inflamed and painful 
ulcer may soon appear at a point where an insect bite occurred, or 
at an abrasion in the skin where the infection has gained entrance. 
This may be accompanied by sudden onsets of headache, aching pains, 
chills, prostration, general weakness, and fever. In some cases 
no external lesions are found. 
In wild rabbits a spotting of the liver and spleen with 
yellowish or whitish flecks is one of the most characteristic and 
easily recognized symptoms. Stupor or evidence of sickness in a 
rabbit should be regarded with suspicion, especially if an epi- 
zootic disease is prevalent. Diagnosis is made by inoculating 
guinea pigs or other susceptible animals with spleen or liver of 
a suspected rabbit or other wild animal and then examining a cul- 
ture isolated after the animals used in the experiments sicken or 
In addition to wild rabbits and hares, the California ground 
squirrel, Columbia ground squirrel, Utah ground squirrel, desert 
ground squirrel, pine squirrel, yellow-bellied chipmunnk, pocket go- 
pher, woodchuck, opossum, cat, porcupine, house mouse, deer mouse,