Investigations into the Nature, Causation, and Prevention of Texas or Southern Cattle Fever Page: 61
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THE CAUSATION OR ETIOLOGY OF TEXAS FEVER.
fresh blood the corpuscle has a peculiar appearance. Its margin is
irregularly notched and creased, the border may be beset with pro-
jecting spine-like processes and its color may be darker than that of
the normal corpuscle. It has, to use a fitting expression, a wrecked
appearance. This change is more marked in some cases than in others.
Such corpuscles have lost their characteristic flexibility. They retain
their disc-like form, even after normal corpuscles have become shriv-
eled and folded in preparations kept under observation for some time.
The number of infected corpuscles circulating in the blood during
the high fever is usually quite small. It is difficult to make an approx-
imate estimate without careful counting. Probably one or two in a
single field of the 2-mm. objective, or from half to 1 per cent is near
the truth in most cases. In some, however, a long search is neces-
sary before one is brought into view. When the number grows larger,
death is not far distant and may be expected within twenty-four
hours. Toward the fatal termination, there may be from 5 to 10 per
cent of the corpuscles with the pyriform parasites present. Fig. 2
on Plate v is an illustration of a group of such infected corpuscles taken
from the blood on the last day. Very rarely large numbers of parasites
may be present and yet the animal recover. The only case of this kind
is No. 49, in which hemoglobinuria appeared at the same time. When
present in considerable numbers in the blood the infected corpuscles
usually appear in groups in the field of the microscope, as is shown in
the figure referred to, and not uniformly distributed.
When the fever has subsided and the number of red corpuscles has
been greatly diminished, the parasites disappear quite rapidly from the
blood. In fact, the reduction of temperature usually coincides with the
more or less complete disappearance of the infected corpuscles, and
their place is then taken by the large number of embryonic corpuscles
which begin to replace the losses. An occasional infected corpuscle
may be detected for some days or even a week after recovery has set
in. But they are so scarce that their detection is more of an accident.
After the subsidence of the fever, when there is a general sinking of
the vital powers, leading to death, the parasites may linger on in the
blood in small numbers or they may disappear as in recovering cases.
Parasites in internal organs.-With only 1 or 2 per cent, or even
10 per cent, of infected corpuscles in the circulating fluid, it would be
difficult to account for the enormous daily losses of blood corpuscles in
the acute fever. The difficulty is cleared up by sacrificing an animal
in the earlier days of the fever and examining the internal organs for
infected corpuscles. Large numbers of parasites are found within cor-
puscles in the capillary blood of congested areas, such as those of the
heart muscle and of the omentum. In the latter membrane there are
delicate fringes containing capillaries which may be placed entire on a
slide and examined with the highest objectives. In such capillaries in
the fresh condition, with perhaps a little iodized serum added, the pale61
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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/m1/61/: accessed April 25, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting University of Texas Health Science Center Libraries.