shed portions of the fleece. The report on 
these samples stated that a distinct break in 
the wool was evident in 7 of the 8 samples. 
Representative of these anatyses are the 
following (12): 
Lamb No. J+7 : Sample % blood. Small lock was 4 
inches long. Remainder of sample l}i inches long. 
Indicates the portion 2% inches long was mostly 
shed. Each portion sound. First growth is cotted 
and weathered. Second growth shows distinct crimp 
and is soft handling. 
Lamb No. 122: Sample blood. Length 3}i inches. 
Break 2}i inches from the tip (first growth). Portion 
on each side of break is sound. Weathered portion is 
harsh handling and felted. Short portion appears 
normal. 
Lamb No. 1^0: Sample % grade — about 2J4 inches 
long. Break in middle of sample. Some samples 
indicate complete shedding or loss of fiber outside of 
break. The weathered exterior portion is sound but 
appears dead or oxidized. The later growth is sound, 
appears normal having distinct crimp and good body 
(or substance). 
Not all of the lambs with broken fleeces 
gave positive agglutination tests. However, of 
17 lambs with evident wool damage, 7, or 41 
percent, were positive, whereas only 15 percent 
of the entire flock gave positive reactions. 
Any serious illness in a sheep may cause 
damage to the wool, and it is emphasized that 
this is an additional economic loss to owners of 
tularemia-affected bands. 
No case of human infection was associated 
with this flock of infected sheep, although the 
owner, the herder, and the dipping crew experi- 
enced gross exposure in handling sick and dead 
animals and in handpicking ticks from sick 
animals. 
Idaho Epizootics, 1952 
Several large bands of sheep, designated here 
as flocks A, B, C, D, and E, were affected with 
tularemia on the Arco Desert in central Idaho 
during the spring of 1952. We were first in- 
formed of this outbreak by Dr. F. X. McArthur 
of the Idaho Livestock Disease Control Labora- 
tory at Boise. Dr. McArthur forwarded two 
refrigerated jars of guinea pig tissues to the 
Rocky Mountain Laboratory. One sample was 
from an animal that had been injected with 
tissues of a lamb from flock A at Oakley, Idaho. 
This lamb had died and portions of the liver 
had been forwarded to the Boise laboratory by 
Dr. R. M. Thornburg of Burley, Idaho. Inocu- 
lum from this sample produced typical lesions 
of tularemia in guinea pigs, and a culture of 
P. tularensis was established. The strain 
proved to be highly virulent for domestic rab- 
bits as has been found characteristic of strains 
isolated from sheep. The other sample sent by 
Dr. McArthur contained tissues from a guinea 
pig that had been injected with ticks, D. ander- 
soni, removed from sheep of flock D, Ketchum, 
Idaho. We were unable to demonstrate infec- 
tion in this sample. 
Although the outbreaks had subsided by the 
time our tests were completed, two trips were 
made to the area to obtain additional samples 
and to obtain firsthand information on the 
extent of the epizootic. 
Histories and laboratory findings on the 
several flocks follow. 
Flock A 
Headquarters ranch for the flock A sheep is 
near Oakley, Idaho. Four separate bands of 
these sheep were grazed on the Arco Desert 
during the spring of 1952 and one band was 
severely affected by the epizootic. The imme- 
diate history of this band as related to us by 
the owner was as follows: 
One-half of the band was turned out to graze on the 
desert north of Milner, Idaho, on April 5. The re- 
mainder was turned out on April 7. The total band 
contained about 2,200 ewes and lambs. 
The first sign of illness was observed about April 20 
when a few lambs were noticeably stiff. By April 27, 
or 28, about 400 to 500 lambs were conspicuously ill 
and a few had died. 
On April 28 or 29, two sick lambs heavily infested 
with ticks were brought into the Thornburg Veterinary 
Clinic at Oakley, Idaho, where autopsies were per- 
formed and tissues sent to Dr. Scott B. Brown, In- 
spector-in-Charge, State of Idaho Sheep Commission, 
Boise, Idaho. A tentative diagnosis of tularemia was 
made by Dr. R. M. Thornburg. (Dr. Brown tested 
these tissues in experimental animals. Test animals 
died and showed lesions suggestive of tularemia. 
Tissues from test animals were forwarded to the Rocky 
Mountain Laboratory, where cultures of P. tularensis 
were isolated after animal passage.) Following the 
recommendations of Dr. Thornburg, this band and 
two others were sprayed on May 1 with a formulation 
containing benzenehexachloride to kill the wood ticks 
which were extremely abundant on the animals. One 
band was sprayed with lindane, which also contains 
benzenehexachloride. The general condition of the 
sheep improved markedly after spraying and losses 
moderated. About 28 lambs died in this band and 
a total of about 20 lambs died in the other 3 bands. 
Tularemia in Sheep ami in Sheep Industry Workers in Western United States 
6 
