Investigations into the Nature, Causation, and Prevention of Texas or Southern Cattle Fever Page: 13
301 p. : ill. (some col.) ; 24 cm.View a full description of this book.
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HISTORICAL REVIEW.
Perhaps the most important and special contribution to the subject
since the earlier investigations of 1868 is the determination of the
boundary line of the permanently infected district by Dr. D. E. Salmon
(5, 6, 7).* From what has already been stated it will be readily under-
stood that this line marks the northern limit of the territory from which
cattle may carry the infection into the territory north of this line. On
the other hand to cross this line from north to south obviously places
cattle in the position to contract Texas fever under favorable conditions.
The investigations of Dr. Salmon have shown that this permanently
infected area does not extend north of the 37th parallel of latitude ex-
cepting along the eastern slope of the country, where it extends half-
way between the 38th and 39th parallel. The order of the Secretary of
Agriculture issued February 26, 1892, puts the following States and
Territories entirely within the permanently infected area: South Car-
olina, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, and
Indian Territory. The following are crossed by the boundary line and
are therefore not entirely within the infected area: Virginia, North Caro-
lina, Tennessee, Oklahoma, and Texas. The line as at present defined
begins at the Atlantic coast, passing westward on the 38th parallel, and
follows the lower boundary of Maryland to the Potomac. It then passes
westward across Virginia as far as the eastern slope of the Blue Ridge,
which it follows in a southwesterly direction through North Carolina, thus
exempting the cooler mountainous regions of these two States from per-
manent infection. It continues in a nearly westerly direction across
the southern strip of western North Carolina and the southern portion
of Tennessee. Across the Mississippi it follows the northern boundary
of Arkansas and that of the Indian and Oklahoma Territories and
finally passes southward through Texas on or near the 100th meridian.
In addition to this work of accurately defining the territorial distri-
bution of the infection nothing has been done to add materially to the
permanently valuable knowledge concerning this malady. Although
attempts have been made to discover the cause they were not success-
ful, as we shall be able to show. In 1889 the first systematic experi-
ments were made by the Bureau of Animal Industry and these were at
once fruitful in the discovery by one of us of a peculiar micro-organism
in the red blood corpuscles which corresponds in every respect with
what we should expect as the true cause. At the same time the other
showed by field experiments that the cattle tick was somehow necessary
to the transmission of the disease. These observations were fully con-
firmed in 1890. In the fall of the same year it was observed that when
young ticks hatched artificially are placed on cattle there is a sudden
extensive loss of red blood corpuscles accompanied by fever which
could in no way be explained by the simple abstraction' of blood. This
discovery, at once followed up by additional experiments, brought to
light the remarkable fact that Texas fever is caused by putting recently
*These numbers refer to the publications on this subject, p. 14.13
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Smith, Theobold & Kilborne, Fred Lucius. Investigations into the Nature, Causation, and Prevention of Texas or Southern Cattle Fever, book, 1893; Washington D.C.. (https://texashistory.unt.edu/ark:/67531/metapth143538/m1/13/: accessed March 28, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting University of Texas Health Science Center Libraries.