w nil progressive illness, prostration, death. 
The affected animals will be heavily infested 
with wood ticks around the head, chest, and 
l>ell\ Because of the association with ticks, 
epizootics are strictly seasonal, occurring in the 
spring months. Illness and fever rather than 
paralysis should distinguish tularemia from tick 
paralysis, which also may affect a flock in sud- 
den outbreak proportions. The heavy tick 
infestations associate tularemia outbreaks with 
special habitats, that is, with sagebrush areas 
in range land. It is not yet recognized as a 
disease of feed lot animals. The presence of 
unusual numbers of dead, or sick, tick-infested 
jackrabbits in the epizootic area should also 
suggest tularemia. 
Human Tularemia and the Sheep Industry 
Among the first human cases of tularemia 
reported in the sheep industry were two which 
originated in the general vicinity of Miles City, 
Mont. ( 14 . ). Both were of the ulceroglandular 
type, with onsets in August and May, respec- 
tively. One patient gave a history of being 
bitten by ticks; the other reported no definite 
source of infection except that he worked with 
sheep and had not handled rabbits. 
Four Montana cases of tularemia from sheep 
contact were reported by Winter, Farrand, and 
Herman (15). All patients had marked pul- 
monary symptoms but all recovered. The 
possibility of a primary pneumonic tularemia 
has been denied by some workers, who insist 
that lung involvement is a secondary process. 
We can only state that pulmonary complica- 
tions are very common in sheep-contact cases, 
and the handling of sheep, sheep pelts, or wool 
loaded with highly infectious tick feces would 
afford abundant opportunity for infection by 
inhalation. 
From the time the late Dr. R. R. Parker 
recognized tularemia as a tickborne disease, 
he kept records of all cases in western United 
States that came to his attention and he sent 
many letters of inquiry to physicians and 
State health officers requesting data on such 
cases. Information on cases associated with 
the sheep industry has been kept separately 
because of the interest of the Rocky Mountain 
Laboratory in tularemia as a disease of sheep. 
Additional information was obtained in 1944 
by means of a questionnaire sent to physicians 
throughout the sheep-raising area of the 
western States. This questionnaire especially 
requested information on sheep-contact cases 
of tularemia. A separate circular letter was 
addressed to members of the sheepshearers 
union, requesting information on illnesses 
associated with their work. 
Table 3. Occupational incidence of tularemia in the 
sheep industry, by State, 1934—52 
Occupation 
Colorado 
Idaho 
Montana 
Nevada 
Oregon 
Utah 
Wyoming 
Total 
Shearer . _ _ _ _ 
14 
9 
4 
1 
1 
15 
20 
64 
Owner 
1 
4 
34 
15 
54 
Herder.. _ _ 
3 
4 
7 
2 
2 
5 
19 
42 
Housewife 
3 
1 
4 
Other or unknown 
2 
2 
12 
I 
9 
25 
Total 
20 
19 
60 
3 
3 
20 
64 
189 
Table 4. Incidence of tularemia in the sheep 
industry, according to month, by State, 1934—52 
Month 
Colorado 
Idaho 
Montana 
Nevada 
Oregon 
Utah 
bt 
O 
Total 
January.. 
February _ .... 
i 
1 
March _ _ _ 
April . 
1 
2 
2 
1 
10 
--- 
... 
1 
4 
8 
3 
26 
May.. . . 
June 
11 
8 
5 
31 
7 
1 
1 
2 
2 
3 
29 
10 
84 
26 
July 
5 
1 
2 
4 
12 
4 
August.. . .. 
1 
3 
September. _ „ _ 
1 
2 
3 
October.. 
1 
1 
November. . 
1 
1 
December 
Unknown 
5 
3 
3 
1 
... 
8 
8 
28 
Total . 
20 
19 
60 
3 
3 
20 
64 
180 
Public Health Monograph No. 28, 1955 
II 
