1. The blood of southern cattle containing the piroplasma produced the
disease when injected into a healthy susceptible animal.
2. The animal with piroplasma in its blood, did not convey the disease,
in the absence of ticks, to a susceptible animal kept with it.
3. The animal with piroplasma in its blood and covered with ticks
conveyed the disease to a susceptible animal kept with it.
4. The ticks hatched and raised in glass vessels in the laboratory, when
put on susceptible animals, infected them.
5. Ticks taken from cattle harboring the piroplasma, and put on the skin
of susceptible animals, or on their pastures in the warm season,
infected the exposed stock.
6. The six-legged larvæ developed in the laboratory from the eggs of
mature ticks, taken from cattle having the piroplasma, conveyed the
disease.
7. On bare pastures as far south as Washington the winter frosts
destroyed the ticks so as to render the pastures safe on the following
season.
8. Ticks artificially raised in a warm laboratory, produced the disease
when placed on susceptible cattle in a warmed stable (65° to 80° F.) in
winter.
9. In the Gulf states, in stables which the cattle occupy constantly or
enter twice daily for milking or feeding, the ticks may live through the
entire winter. The same has occurred in the warm swill stables in the
north.
10. When taken into a new locality, it is rarely the mature ovigerous
ticks that bite and infect the native cattle of the place, but the next
generation of larvæ, so that time must be allowed for the laying and
hatching of ova.
11. Ovipositing usually occupies about a week, while hatching varies
with the temperature from two to six weeks.
12. Cases can be adduced in which native cattle followed, on the same
pasture, the tick-bearing infecting cattle, and remained for a week or
more, and yet escaped, the larvæ being as yet unhatched from the ova.
Other native cattle, following these two or three weeks later, perished
almost without exception.
13. This delay in the hatching may be indefinitely prolonged, and thus
in the southern states, the winter may be tided over, without the loss
of vitality in the ova, especially if it is covered by leaves, moss,
wood, or decaying vegetable matter.
14. When dealing with lung plague in Chicago in 1888, I noted the facts
that every cow that entered a city stable through the stock yards during
the dry, hot, midsummer weather died of Texas fever within a month,
while those that passed through the same yards during a particular rainy
week, all escaped. Berkau has shown that, in the absence of the coating
of the glutinous saliva, the eggs do not hatch, and here we may assume
that this covering was washed off by the rains and the eggs perished.
15. It has long been noticed that the ticks are scarcely at all
dangerous to young calves living on milk. This applies not only to
calves born of cows native to infected localities, and therefore
possibly having a congenital immunity, but also to the calves of
northern and susceptible cows, and which were exposed simultaneously
with their dams. It suggests a special defensive power in even the
bovine system when sustained on animal food. In the Bureau of Animal
Industry experiments, calves of four months, already using vegetable
food freely, sickened but still, as a rule, recovered.
16. The Bureau fed three cattle with adult live ticks (2000 to one
animal) but no infection resulted.
17. Four cattle were injected intravenously with the liquid charged by
crushing ticks in a mortar with distilled water. In some cases the
liquid was put through a Pasteur filter, in others only through two
thicknesses of filter paper. No infection ensued.
18. Lignieres injected, subcutem, in different animals the pulp of the
ticks at all stages of life, ground in a mortar with distilled water,
but found in no case tristeza as the result nor any destruction of red
globules.
The apparent paradox involved in the last three items probably finds its
explanation in the statement of Nicolle and Adil-Bey that, in biting,
the tick instils into the wound a venomous saliva which causes local
congestion and infiltration and presumably operates on the blood
globules as well. Curtice describes the two racemose glands situated
under the head shield, the secretions of which are pressed out by the
movements of the mouth ring and appendages. How much of this irritant
and toxic action is inherent in the saliva, and how much due to the
protozoan contained in it, has not been shown. Nicolle, Adil-Bey and,
later, Lignieres showed a similar toxic property in the blood. Three to
five cc. of blood taken from an acute case at the crisis and injected
into the marginal vein of the ear in a rabbit, killed the subject in a
few seconds. A similar amount thrown into the peritoneum of a Guinea pig
destroyed life in a few minutes. It is probable that the dilution of the
venom in the mass of tick pulp and distilled water reduced its toxic
quality to such a low ebb that the red globules were comparatively
unaffected by it and successfully resisted the attacks of the microbe.
The name _Boöphilus bovis_ was given to the bearer of the Piroplasma by
Cooper Curtice who made a special study of the tick, and its
development. For the description see _Parasites, Ixodes_. Among the most
marked and distinctive features of the female are the extreme shortness
and relative breadth of the rostrum, the slender palpi, the eight rows
of spines on the lower surface of the labium, the smooth mandibles with
terminal hooks, the limbs long, slender, in seven segments, and each
furnished with a terminal pad (pulvillus) and one hook (fore limbs) or
two hooks (hind). Curtice has identified the ticks of hæmoglobinuria in
various other countries with the boöphilus. The _Garrapata_ of Mexico
and the West Indies, the Hæmaphysalis rosea of Cuba (Koch), the Ixodes
Annulata of Florida (Say), the Ixodes Dugesii of Italy (Nequin), the
Ixodes Algeriensis and the Ixodes Egypti he found to be identical. There
may be some doubt as to the Rhipicephalus Annulatus Microplus of Buenos
Ayres, but as it agrees with the boöphilus in size, in the thickness of
its rostrum, in the eight rows of hooks on the lower surface of the
labium, in its host and habits, in the fact that it transfers the
piroplasma to cattle, and that it prevails on the same continent in what
were formerly colonies of Spain it is in all probability the same tick.
Curtice holds that it was originally a North African tick, which was
carried by the Spaniards to their American colonies. The Rhipicephalus
Annulatus of Roumania is probably the same, together with the ticks that
convey the Piroplasma in the other countries of Europe. There remain the
Hæmaphysalis of South Africa and the “Scrub-tick” of Australia to be
identified with, or differentiated from the Boöphilus. The life history
of the Queensland “scrub” tick coincides with that of the boöphilus of
America (Pound). As Australia derived her cattle from Britain it is
improbable that the tick was imported from Europe.
_Lesions._ If the course of the disease has been short, followed by an
early death, the carcass may be full and rounded, but if the animal has
been sick for five or six days there is marked loss of condition and
weight—emaciation. As after any other affection occurring during very
hot weather, decomposition sets in early, though not quite so speedily
as in anthrax, in which the subject dies full of rich blood. Something,
too, depends on the condition at death, putrefaction being manifestly
slower in protracted and debilitated cases. The color of the skin, the
mucosæ and normally white tissues varies in the same way. As it has been
largely seen in our northern States (and Australia) in fat cattle, which
contracted the disease in railway cars, cattle markets, or dealers’ or
butchers’ parks, etc., the deep orange hue of the white tissues is one
of the most marked features, and even the muscles have a deep mahogany
yellow hue. In poor milch cows and stock cattle in the South, on the
other hand, the icteric hue is often conspicuous by its absence. Cattle
killed early for experimental purposes may also show less icterus. The
color appears to be influenced largely by the abundance of red globules
in the blood when the animal was attacked, by the rapid destruction of
these globules, and the saturation of the blood and tissues with
hæmoglobin in solution. The presence of ticks on the skin, especially
along the ventral aspect, inside of the thighs, on the scrotum, udder or
perineum, sufficiently explains the number of minute infiltrations into
the derma, the oozing of blood or serum, and the matting of the hairs
into little tufts.
The _pale, watery condition of the blood_ was recognized as one of the
most constant features in 1868, together with the disappearance of the
red globules. The clot is remarkably soft and, at the crisis of the
disease, the serum is of a reddish hue by reason of the hæmoglobin in
solution. When, however, the urine is no longer stained, the hæmoglobin
having been eliminated, the serum assumes its normal pale amber hue. For
the first counting of the red globules in this disease we are indebted
to the Bureau of Animal Industry. The average count in healthy cattle
approximated to 6,000,000 per mm. of blood, and in three days this would
descend to 4,000,000, 3,000,000, 2,000,000 or even 1,183,000. The rates
of decrease was ⅛ to ⅙ of the entire number in one day. In case of
recovery the repair of the red globules was slow, from one to two months
being required to bring them up to the normal standard. Lignieres claims
recoveries after the count had gone as low as 300,000 per mm., and in
fatal cases, a few hours before death, it may be but 31,000 per mm.
In high conditioned animals, with high fever often aggravated by travel,
the muscles may be dark and firm, but in those out of condition and in
the advanced anæmic stages of the disease the muscles are pale, and
there may be subcutaneous œdema below the chest and belly. These last
features are especially noted by Smith and Kilborne.
The _lungs_ are usually normal. Sometimes limited congestions,
punctiform petechiæ, emphysema and small areas of œdema or hepatization
are noticed (Smith and Kilborne).
The _pericardium_ contains a little bloody serum and is marked by
petechiæ.
The _left heart_ is usually empty, but the _right heart_ full of fluid,
or later, of clotted blood, in the latter case without buffy coat. The
endocardium, and especially on the musculi papillares, is marked by
petechiæ, punctuate or in considerable patches. The cardiac capillaries
are full of blood, with numerous piroplasmata.
The _peritoneum_ often contains a little reddish serosity, and a slight
gelatinoid exudation is sometimes found around the kidneys or elsewhere
in the abdomen. Petechiæ are frequent.
The _stomachs_ usually show petechiated spots on the mucous membranes,
and more or less diffuse congestion. Sloughing of the mucosa at such
points is not uncommon, and even perforation of the folds of the third
and fourth stomachs. The Bureau of Animal Industry and Lignieres both
found these stomach lesions very inconsiderable. The smaller pinhead
erosions described by Gamgee were identified by the Bureau of Animal
Industry as bites of the strongylus convolutus. The _small intestines_
are usually moderately congested.
The _cæcum_ and _colon_ show more congestion, becoming at times of a
deep red or almost black hue, and considerable extravasation of blood
may take place. This is especially marked in the rectum, which may be of
a port wine hue, comparable to that seen in rinderpest or hæmorrhoidal
anthrax. The fæces are often dry and massed in balls in cæcum and
rectum, while if diarrhœa has set in, the discharges may be colored with
blood or blood elements. Yet in the cases reported by the Bureau serious
lesions of the intestines were rather the exception, and some subjects
showed scarcely any lesion.
The _liver_ is usually enlarged, averaging three to five pounds heavier
than in a healthy ox of the same weight. In these enlarged and congested
cases it is of a deep yellowish brown color, and often shows yellow
spots on the darker ground. Microscopically each acinus has a bright
yellow centre from which yellow radiating canals diverge to join the
peripheral gall duct. In the superficial or portal portion of the
acinus, the hepatic cells are granular from fatty change, yet the
nucleus is usually still recognizable. Toward the central zone it may
have disappeared. The further this has advanced, the softer, the more
easily pitted and the more friable the liver. The congestion of these
radical gall ducts with the dense colored bile, displays the structure
of the acini in a clear and beautiful way, which no injection can
accomplish. When the affected tissue is teased out and placed under the
microscope the inspissated contents of the bile canaliculi may be seen
as yellow cylindroid casts sometimes bifurcated to represent the union
of the two canals. If stained in Ehrlich’s acid hæmatoxylin, the
necrotic elements refuse to take the stain so that the contrast between
the dead and the living tissues is enhanced. Fatty degeneration is
common in the liver of healthy beef cattle so that this is less
significant than the congestion of the acini, and the phenomenal
distension of the radical gall ducts with inspissated bile.
The _gall bladder_ is usually full (½ pint to 1 quart or more), and its
mucous membrane congested and sometimes petechiated. The _bile_ is thick
and viscid, like tar, it may be yellowish green, darkening on exposure
and contains hæmatoidin crystals and abundance of flocculi showing
bright yellow or orange by transmitted light and reddish brown by
reflected light.
The _spleen_ is always enlarged, often enormously so. From an average
weight of 1.5 lb. to 1.7 lb. for a 1000 lbs. ox, it will rise to 2, 7 or
even 10 lbs. One measured 27 inches long by 7½ inches wide and in the
centre 3 inches thick (Rauch). Even in apparent health the Gulf coast
cattle have spleens averaging about 2½ lbs.
The spleen is gorged with blood which appears purple as seen through the
stretched and attenuated capsule, and darker petechial spots are found
at intervals. When cut into, the pulp alone appears dark, brownish red,
grumous, and showing under the microscope many red blood cells, larger
cells granular and undergoing fatty degeneration, yellow flocculi,
crystals of hæmatoidin, and granules of black pigment. It is the excess
rather than the nature of these agents that is significant. The pulp may
be pressed or washed out, bringing the trabeculæ and Malphigian bodies
into view.
The _kidneys_ are most seriously affected in acute and rapidly fatal
cases. There may be œdema, with blood staining and even extravasation on
their lower surface and in the adipose tissue. The gland may be enlarged
and the cortical substance congested of a dark brownish red or black.
Its capillaries are gorged with red globules in which the piroplasmata
are very numerous. The medullary portion is much paler, and with fatty
granules in the epithelium, and oil globules in the tubules. The renal
pelvis is more or less petechiated and marked by extravasations.
The _bladder_ is marked by petechiæ and usually contains some quarts of
urine more or less deeply stained with hæmoglobin. The depth of color is
in exact ratio with the extent and rapidity of the destruction of red
globules, and of the elimination of their coloring matter. When the
destruction is proceeding rapidly the urine may be as dark as port wine;
when their disintegration has lessened it may be pale though the
temperature is still high (105° F.) In slight and tardy cases there is
reason to believe that the redness of the urine may be omitted
altogether as is the icteric discoloration of the mucosæ, and hence
cases seen in animals indigenous to the protozoan fever districts, have
been described as a distinct disease. In these mild cases and advanced
stages there is usually a certain amount of albuminuria remaining. In
the early stages the urine is strongly alkaline, effervesces with acids,
and has a high specific gravity (1030–1040); later when abstinence and
suspended digestion and assimilation causes the patient to subsist on
its own tissues the reaction may become distinctly acid and the specific
gravity reduced (1010–1020). It no longer effervesces. During
convalescence while there is a great deficiency of red globules and
other blood solids, the urine tends to become pale and watery, of a low
specific gravity, and lacking in even its normal pigments.
The _womb_ will at times show petechiæ and in pregnant cows the fœtus
will show sero-sanguineous effusions or even extravasations in the chest
or abdomen, and hæmoglobinuria (Lignieres).
_Incubation._ Outbreaks occurring in the North, in herds into which
southern infected cattle have been brought, were at first held to
indicate an incubation of thirty or forty days (or even sometimes
sixty-five), but this is now explained by the time required for the
laying and hatching of the eggs of the mature ticks and the evolution of
infecting young larval or seed ticks. The actual incubation, as shown by
the subcutaneous or intravenous injection of the blood of an infected
ox, extends from three to ten days. The hyperthermia is usually shown on
the third day, and the more manifest outward symptoms on the sixth.
Extreme heat of the weather, a special susceptibility of the animal
infected, and especially a large dose of the blood and protozoa will
hasten somewhat the onset, but three to six days may be set down as the
rule after the ticks have introduced the parasite into their victim.
Cattle taken from the northern states and placed on southern pastures,
or passing over trails already well stocked with the ticks, are infected
at once and sicken in from three to ten days. Cattle in their northern
home placed on a previously uninfested field with southern cattle just
arrived, do not suffer for thirty, forty, sixty, and in exceptional
cases, even ninety days. The paradox is explained by the time wanted for
the laying of the eggs and the hatching of the tick larvæ. The female
tick does not lay eggs until she is fully mature, and if the ticks on a
southern ox are still immature there is a variable period of delay until
the eggs are mature enough to be deposited. Then the ovigerous tick
drops off her host and spends one week in laying her eggs. In warm
weather these eggs take three to four weeks to hatch, so that usually
five weeks elapse before the young (seed ticks) can climb upon the ox
and infect him. Add three to six days more for the actual incubation and
we account for about six weeks of delay in the appearance of the disease
in northern cattle. If we consider further that a wet season occurring
after the eggs have been laid and before they are hatched tends to
divest them of their protective covering and to expose them to
destruction, and that, in any case, a cold season will delay the
hatching until the recurrence of warm weather, and that the absence of
bovine victims will doom the new-born larva to an arrest of development,
so that a further indefinite delay may be entailed, we have abundant
explanation of the frequently delayed evolution of symptoms. Yet in
general terms the apparent prolongation of incubation is due to
fortuitous circumstances which delay the infection, and not to any
actual extension of the incubation itself.
_Symptoms of Acute Type._ Cattle infected outside the area of habitual
prevalence and stock from noninfected districts, conveyed into the
infected ones in hot weather, usually contract the disease in its acute
and fatal form. The period of the year is often significant, a number of
animals being attacked at once in the hot dry period of late summer or
autumn—July to September in North America, February to May in Argentina.
The first symptom is a rise of temperature, and this may last two or
even three days before other morbid phenomena are noticed. It may rise
to 104° F. in the first day and later to 107°, 108° or 109°. The more
acute the case and the hotter the weather the greater the rise. The
highest records are obtained late in the day, the lowest in the morning.
The temperature often rises for two to four days, and then suddenly
drops with the occurrence of collapse and imminent death. While the
thermometer is of the highest value in taking the temperature, yet the
extraordinary hyperthermia is easily detected by grasping the root of
the horn or ear, or by feeling the nose, feet, anus or lips of the
vulva.
After 2 or 3 days the respirations become accelerated to 60 to 100 per
minute, and the pulse to 90 to 100 or more. There is complete loss of
appetite and rumination after the development of these symptoms, the
mouth is hot and it may be dry, the muzzle dry, the head pendent, the
eyes dull or semiclosed and congested (usually icteric), the bowels
confined, to be relaxed again as the fever subsides. A disposition to
stand or lie down in water has been frequently noted. Nervous symptoms
are usually present. The extreme dulness, languor, and apathy, the
drooping head and ears, the unsteadiness of the support the animal
staggering or propping himself up by spreading all four limbs, and the
tendency to assume and retain a recumbent position, are marked phenomena
in our domesticated northern cattle. The paresis may absolutely
incapacitate the animal from getting up. In our wilder range cattle it
may show itself in active delirium and Lignieres notes the same of the
Pampas cattle in Argentina. The animal lying dull and apathetic
(triste), on being approached may raise his head, open his eyes and
glare threateningly at the intruder. Sometimes when trembling violently,
and swaying ready to fall, he will marshal all his remaining energy to
plunge at a man on foot or mounted. Some have become blind and
unconsciously walked against obstacles, others have been noticed to run
in wide circles.
The milk secretion is suppressed, any little that can be drawn in the
advanced stages having a thick, creamy appearance. Abortion is common in
the pregnant cow.
The condition of the urine has, however, always drawn especial attention
and the names _red-water_ and _hœmoglobinuria_ have accordingly been
largely applied to the disease. When, in infected areas, the milder
types of the disease have failed to show _red-water_ (Jamaica), the
identity of the affection with Texas fever has even been denied. Shortly
after the rise of temperature, the urine becomes turbid, and this
gradually encreases to a more or less deep red. It assumes its darkest
hue when the destruction of red globules is most active and during
convalescence it disappears. The suppression of urinary secretion may
account in some cases for the absence of this symptom even at the crisis
of the fever, yet, as a rule, it is present at such time, and, even
though it may have escaped notice during life, the _red-water_ is found
in the bladder at the necropsy. It may be of all grades, from the merest
tinge of redness to a reddish brown, coffee-grounds, or blackish aspect.
The coloration is not due to red globules, but to the hæmoglobin which
has escaped from the disintegrating globules, and been eliminated by the
kidneys. It is always associated with albumen, and, in the advanced
stages and during convalescence, when the elimination of hæmoglobin has
ceased, that of albumen continues in small amount for weeks.
The thin, watery appearance of the blood when the disease has reached
its height, is constant and even more characteristic than the
_red-water_. A single drop drawn from the skin will show to the naked
eye the pale, thin, transparent appearance, but examination under the
microscope will confirm this. It remains, too, for a length of time,
being recognizable for a month in cases of recovery. In connection with
the watery blood, the mucosæ and the muzzle (if naturally white) assume
a pallid aspect. This is best marked in the absence of icterus, yet even
with the yellow discoloration, the absence of ramifying red vessels is
very characteristic.
The bowels are at first constipated and the fæces passed in small, hard
balls. Later they may assume a reddish brown or chocolate color, and a
covering of mucus and fine blood clots. Diarrhœa supervenes in some
cases. In passing the fæces, the everted mucosa usually shows a dark red
color.
_Course and Duration._ Acute cases, above all if traveled or otherwise
excited, may terminate in death in 24 to 48 hours. More commonly death
will take place in 4 to 7 days. Some patients survive longer, but owing
to the extraordinary loss of blood globules and the lesions of important
solid tissues they are unable to rally, become steadily weaker and
perish in from two weeks to three months. Such animals are pale and
bloodless, weak on their limbs, careless of food, and encreasingly
emaciated. The pulse is weak and irritable and the eyes sunken. The
temperature becomes normal or nearly so, soon after the suspension of
the hæmoglobinuria. In cases of recovery there remains for a month or
more an unnatural pallor, with marked loss of condition and weakness
which are only gradually overcome. Convalescent animals are liable to
die of indigestion when overfed.
The _mortality_ averages not less than 90 per cent. in susceptible
mature cattle from a healthy district in the hot season. Later, from
October onward, the tendency is to a milder type of disease and a
greater ratio of recoveries.
_Symptoms of the Mild Type._ This is seen mainly in cattle indigenous to
the Texas fever district, in sucking calves, and in mature cattle from
healthy districts but attacked during the cool or winter season. It can
be produced at will by placing a limited number of ticks (5 to 20) on
the skin of susceptible cattle, especially in the cool season. Again, it
occurs as a relapse in cattle that have survived an attack earlier in
the season.
Though there are all gradations from the violent type, yet we may set
down as mild all cases in which the temperature does not rise above 105°
F., running frequently about 103° F. There is loss of appetite, dulness,
languor, costiveness, scanty urine, albuminous but not hæmoglobinuric,
pallor of the mucosæ, and marked loss of condition. Examination of the
blood shows the presence of the parasite in the red globules but usually
in the coccus or round form only, and the destruction and disappearance
of the globules is much less marked so that, though the blood is anæmic
and watery, it is not nearly so much so as in the violent and fatal
cases. Without the examination of the blood it may be impossible to
distinguish these cases from other febrile affections, yet occurring as
they do in the infected district in a number of animals at once, in the
cooler season, and showing albuminuria, and marked anæmic symptoms, they
should lead to suspicion and a search for the boöphilus on the skin, and
the oligocythemia and the protozoa in the blood.
_Differential Diagnosis from Anthrax._ As anthrax is the one disease
with which Texas fever is most likely to be confounded, it may be
profitable to collect in tabular form their differential features:
=Protozoan Cattle Fever.= =Anthrax.=
A disease of given districts, Prevails in rich, swampy
wooded, swampy, uncultivated, impermeable soils: not
and places where cattle from permanently implanted on open
these districts are taken. well drained lands.
Always shows Boöphilus, minute or Has no essential connection with
mature, on the skin of the the Boöphilus: latter usually
patient. absent.
Extends in warm season, as the Practically never conveyed by the
Boöphilus from an infected Boöphilus.
district is introduced.
Can be carried by the Boöphilus
apart from cattle.
Infection destroyed by winter Infection not destroyed by winter
frost above 35° of N. latitude. frosts.
Attacks bovine animals only. Attacks mammals, generally,
especially herbivora.
Lapse of 5 to 6 weeks after Outbreak may occur at once after
introduction, for tick introduction of infection.
development, precedes outbreak.
Confined mainly to summer season. Occurs at any season: most
prevalent in summer.
Sucking calves nearly immune. Sucking calves susceptible.
Mucosæ become increasingly pale; Mucosæ dusky brownish red, not
icteric in violent attacks. pallid, nor icteric.
Urine red or blackish in acute Urine exceptionally red: blood
cases at height of the disease. globules, in some cases.
Hæmoglobin. Albumen.
Blood becomes increasingly thin Blood becomes thick, tarry,
and watery: Oligocythemia. incoagulable; not watery nor
oligocythemic.
Blood reddens more or less in air: Blood reddens little, or not at
then becomes darker. all on exposure.
Spleen greatly enlarged, purplish, Spleen greatly enlarged; pulp very
often firm: pulp reddens dark does not redden in air.
slightly in air.
Liver enlarged, congested, often Liver enlarged, congested, dark
yellow, with fatty and necrotic red or violet.
areas: remarkable yellow
injection of radical bile ducts.
Bile abundant, thick, tarry. Bile fluid.
Kidneys pale, or congested, black. Kidneys congested.
Lymph glands slightly enlarged, Lymph glands enlarged; often
petechiated or (rarely) hæmorrhagic, black; peripheral
hæmorrhagic. œdema.
Pallor in violent cases, in Tissues generally reddish,
plethoric, icterus of tissues, bloodvessels dark, prominent.
especially of white ones.
Muscles in acute cases mahogany Muscles pale, grayish, unless they
colored. are seat of congestion or
extravasation.
Blood and its red globules show Blood shows bacillus anthracis,
the pyroplasma in different but no pyroplasma.
forms.
_Treatment._ Up to the present medical treatment has been essentially
unsatisfactory. Lignieres gave quinia sulphate in large doses by the
mouth, and in doses of 2½ drams subcutem daily, before and during
infection without any visible effect on the progress of the disease.
Methylene blue to (¾ to 1¼ dr.), salicylate of soda (7½ drs. daily),
arsenious acid (1¼ dr. daily), cacodylate of soda (7½ grs. subcutem)
were also tried with no good result. The Metropolitan Board of Health,
New York, claimed a succession of recoveries under the use of carbolic
acid in the drinking water and sprinkled on the ground so that the
animals inhaled it. The cases were, however, the survivors after the
first and more acute cases had perished, and the results no doubt
depended largely on the mildness of the attacks. The same agent in other
hands has not been equally successful. A large number of other agents
have been used in vain.
Among the most important measures are a laxative food, like flax seed
gruel, a careful picking of all ticks from the surface, the washing of
the skin with a 5 per cent solution of creolin, and the removal of the
animals to a tick-free pasture, lot, or building. This at once arrests
the introduction into the blood of fresh and continuous accessions of
the pyroplasma and, if begun early enough, will determine a mild and
non-fatal case.
_Prevention._ The prevention of the protozoan cattle fever is based on
the life history of the parasite, and may be directed (1st) to the
_destruction of the Boöphilus Bovis_; or (2nd) to _encreasing the
resisting power of the exposed animal, to the Piroplasma Bigeminum. 1st.
Destruction of the Ticks. (a) On the cattle._ The _picking of ticks from
the skin_ is effective if the object is to make the animal safe for a
few days only as the boöphilus habitually clings to the skin of the one
ox from the stage of seed tick to that of ovigerous female, ready to
drop off and lay its eggs. An animal going direct to slaughter may
therefore be sent through an uninfested district, even in the hot season
with a fair amount of safety, after the careful gleaning of the ticks.
The greatest care, however, must be taken to manipulate thoroughly all
parts of the skin and above all, the ventral aspect, the inner sides of
the limbs, the scrotum, udder and perineum. The animals must be shipped
at once after such gleaning of ticks with no further opportunity of
taking on a new supply, the cars and other conveyances must be cleaned
and treated with acaricides and the litter burned as soon as they are
vacated, and the cattle must be passed over no loading banks, chutes nor
yards that may by any possibility be used for other cattle unless these
are going into slaughter house.
The picking will safely remove all the larger larvæ, and the mature
ticks which are ready to lay their eggs, but it cannot be implicitly
trusted to remove also the all but invisible embryos or seed ticks, and
if the host is preserved these grow up and mature, while if they are
accidentally dropped or brushed from the surface, they climb upon the
first available ox and mature on that. By passing from ox to ox they may
be kept alive for a time in the pens adjoining the slaughter house, but
fortunately they do not travel over a few feet and if no cattle escape
from such pens there is small risk of their preservation.
_Dipping_ or _smearing_ to destroy the seed ticks on the skin becomes an
essential adjunct to, or substitute for, picking. The Bureau of Animal
Industry has experimented largely on dips with most important and
valuable results, even if they have proved only in a measure successful
and desirable. Aqueous dips they early discarded. Poisonous agents like
corrosive sublimate and arsenic are liable to poison through absorption
and licking, with the added drawback that neither these nor calcium
sulphide are at all effective in destroying the ticks. Proprietary sheep
dips were abandoned on similar grounds. Baths of cotton seed oil were
introduced by Francis, but proved not quite effective even when phenic
acid, benzine, gasoline, or different mineral oils were added. _Paraffin
oil_ gave the best results, and later a staple sold as _extra dynamo
oil_, which in combination with _sulphur_ (1:100) proved most
destructive to the ticks, was adopted. But in the hot season, when such
dipping is required, any one of these baths produced _heating_, and
illness in the cattle, and together with the exertion and excitement
served to rouse into dangerous activity the germs already present in the
blood. Ophthalmia, too, was a very frequent result. If the cattle could
be kept on their native pastures the dipping might be permissible, but
this was to lose the object aimed at—the wholesomeness of these cattle
on uninfected ranges. When shipped north in the hot weather the losses
were so great as to be prohibitory.
If, however, it could be reserved for use on the southern pastures, to
prevent the maturing of the ticks and the laying of eggs for a future
generation, it might be employed to rid the infested pastures of the
boöphilus, and consequently of infection. The question, then, is reduced
to the comparative advantage of the destruction of the ticks, on the one
hand, and the cost of frequent dipping throughout the warm season, on
the other. The following season there ought to be no ticks left.
Cooper Curtice advocates kerosene 1 gallon in combination with an equal
amount of lard, 1 lb. sulphur, and 2 lbs. pine tar. Melt the lard, add
the sulphur and tar, bring to the boiling point, cool, add the kerosene
with stirring. Rub daily with a brush on the whole skin but especially
inside the arms and thighs. On tick-infested pastures it must be
continued through the season, and if thoroughly done will leave the
fields tick-free the following year. Like oil dipping it would
manifestly be incompatible with immediate shipment on a long railway
journey, but Curtice vouches for its efficacy as a means of eliminating
ticks from southern pastures. The main question is the expense. What
would be perfectly adapted to small herds of very domesticated cattle in
North Carolina would be a herculean and expensive task in the large
herds of Texas. Curtice mentions cotton seed oil, fish oil and even a
small proportion of linseed oil as good substitutes for the lard.
_Destruction of Ticks on Pastures._ Fields, farms and larger areas can
be freed from the boöphilus by the thorough application to the cattle
pastured on them of one of the above-described methods, provided that no
strange cattle are admitted on the land. The ticks are sluggish and,
unless carried on the bodies of animals, do not crawl many feet from
where they drop. If cattle are kept in the next lot, they should not be
allowed to come in contact with the treated or protected stock, but a
double fence with an interval of five or six feet, will prove a
sufficient barrier to the advances of the tick, apart from its bovine
host.
_Cultivation_ of a tick-infested soil for one year or more, with
complete exclusion of cattle from November or December until March or
April of the second year thereafter, will exterminate the ticks. During
the intervening summer there may be plenty of young live ticks on this
land, but, in the absence of the bovine host, and blood, these cannot
reach maturity, lay their eggs and thus leave new generations. In the
course of the second winter therefore they are exterminated. In
restocking such land, it is all important to see that the cattle placed
upon it do not introduce any ticks on their bodies. Equally essential is
it, to see that cattle are excluded from the cultivated land in winter
as well as in summer. During warm days ovigerous female ticks, dropped
from the skins of such cattle, may produce eggs and larvæ to start a new
crop in the coming summer. But as has happened to the wood ticks of the
North, so in the South, cultivation of the soil and the exclusion of
cattle for a length of time, will exterminate the race of ixodes.
_Exclusion of cattle for two winters and the intervening summer_ will
eradicate the ticks even in the absence of cultivated crops. To reach
full maturity and propagate its kind, the tick must have bovine blood.
If therefore the ticks of a whole season (spring, summer and autumn) are
denied bovine victims, and thus cut short in their development, no crop
is left for the succeeding spring. If then a cattle pasture is divided
in two parts by a double fence with an intervening space of 5 or 6 feet,
and if the cattle are confined to one of these parts for a whole year
and are transferred to the second half in January after dipping or
smearing with ixodicide oil they may be kept entirely free from ticks
thereafter. That half of the pasture which is abandoned in the second
year, will be tick-free and salubrious in the third year.
Another resort, advised by Curtice when a large tick-free pasture is
available, is to place the infected cattle in a pen, and _soil_ them for
three weeks, no longer. Then transfer them to another clean pen and
_soil_ them there for three weeks more. Then examine closely, and if
entirely free from ticks they can be put in the large clean pasture.
Should they still carry a few ticks they should be placed in a third
clean pen for two weeks more, when they will be tick-free and may be
turned into the large pasture without the formality of examination. This
is substantially based on the period of parasitism of the tick on the
skin of the ox, and its development from the newly hatched larva (seed
tick), to the ovigerous female. This period is from three to four weeks.
The greater number of the ticks are therefore dropped off as mature
ticks to lay their eggs in the first pen, while the remainder are
similarly left in the second pen. As the stock leaves the two pens in
succession long before the deposited eggs have had time to hatch out,
they can take on no more ticks and emerge from the second pen clear and
safe. The same pens cannot be used repeatedly, as the eggs develop into
seed ticks in 15 days in hot weather, and at once attack cattle.
A stockowner who, independently of his fellows, adopts one of the above
expedients in an infested district, is however confronted by the risk of
the infection of his herd, by the accidental or careless contact of his
cattle with outside ones, and especially with the places where they have
been. A broken fence and the entrance of tick infested cattle, or the
escape of his tick-free cattle into infested lands, will be the death
warrant of all that have not been previously exposed to the disease.
Another consideration is that this rigid seclusion of the protected herd
must be continued indefinitely so long as ticks are maintained anywhere
in the district. The protected animals cannot be driven over a highway
without exposing them to almost certain death. Even if a group of
adjacent stockowners agree to purify their respective farms, they cannot
debar their less careful neighbors from using the highways for
tick-infected stock, nor from turning such out on adjoining fields. The
veriest scrubs, admitted to the highways, woods and unfenced grounds,
keep up the general diffusion of the fever germ and its tick bearer and
undo the best directed efforts of any combination of owners of high
class and valuable stock.
Well directed legislation, excluding cattle for one or two years, from
all woods and unenclosed lands, and enforcing some one of the available
methods for the clearing of fenced and stocked lands (cultivation,
pasturage by cattle on alternate years, frequent dipping or smearing,
passing the stock through a succession of pens), could be made to put an
end for all time to the obnoxious tick. If even some other than bovine
animals should be discovered to harbor the boöphilus and pyroplasma it
could be included in the prohibition and the work made complete. The
results would far more than compensate for any necessary outlay.
Illinois, with 55,414 square miles of area has over 3,000,000 cattle.
The coast states from Virginia to Texas, with Arkansas, Indian Territory
and Oklahoma, amount to 767,215 square miles, and in the same ratio
should sustain 43,340,040 head. A stock of 25,000,000 at $20 per head
would amount to a capital of $500,000,000. Immune from the pyroplasma
these cattle would draw freely on the best blood of the north and under
the milder skies would compete with the northern cattle on more than
equal terms. Living in the open air, they would in the main escape
tuberculosis and the other stable-propagated diseases of the north, and
their dairy and beef products would enter the market free from
suspicion, and command a readier sale, if not a higher price. The stock
themselves could be moved to northern markets at all seasons without
restriction, and escape the serious losses that now come from a sudden
transfer, while pyroplasma-infected and susceptible, to the violent
excitement of travel, and the frost-bound destination. Their owners
could watch the markets and sell in the best, in place of being
compelled, as at present, to hurry them in during November and December,
and to sell often at a ruinous sacrifice. With the extinction of the
boöphilus the present unrestricted pasturage and all other privileges
now enjoyed would return, freighted with a value never borne before, and
the few Southern cattle and cattle products need fear no competition in
the markets of the world, and could no longer be justly subjected to any
restriction.
There would remain the constant danger of the introduction of the
boöphilus anew from Mexico, the West Indian Islands and the Central and
South American States, where in the absence of frosts the boöphilus
cannot be extirpated in the same way, and here accordingly all
importation must be forbidden. Cattle from Southern Florida and from
islands on our Southern Coast may demand a similar exclusion. There is
too much at stake to permit any laxity, and no infected area should be
allowed to send out its cattle until it has been abundantly well proved
that such district or State is absolutely tick-free.
2d. _Immunization: Encreasing the Resistance to the Piroplasma
Bigeminum._ That cattle can be fortified to resist the attacks of the
piroplasma is shown in the immunity possessed by the indigenous herds
generally, in the regions infested with this parasite and the boöphilus.
To begin with, there may be a survival of the fittest, the more
susceptible strains of blood having been long ago cut off. But the
immune southern cattle if kept for years outside of the infested area
and then returned to it, suffer a mortality about as great as that of
northern cattle in the same circumstances. Their earlier immunity,
therefore, is not merely a racial difference, but must be due in
greatest part to an acquired resistance, and further, this resistance is
not permanent but must be renewed at short intervals. The immunity may
be in part acquired in the womb of the infested dam, in the last months
of gestation, but it is chiefly post-natal through the attacks of the
ticks.
_a. Infection of sucking calf._ The indigenous cattle acquire immunity
mainly through the attacks of the boöphilus, in the first month or two
when they are still on an exclusively milk diet, that renders the
piroplasma practically harmless. Following a parallel method, calves,
living on milk alone, can be taken into the infected regions and exposed
to the attacks of the ticks with safety, and with the result of
protection for the future. Escaping the first invasion, they continue to
harbor as many ticks summer after summer, as will reinforce yearly their
acquired power of resistance, so that they continue measurably safe
though spending the life in the area of the infection.
Francis and Connoway applied this to Jersey calves of two to six weeks
old applying to each 25 to 50 ticks. It led to slight hyperthermia, some
dulness and inappetence, but on recovery they all gained flesh and
condition. Two died from exposure but necropsy showed no sign of Texas
fever. The following summer all were infested with 200 to 500 ticks
apiece but not one sickened in consequence. These were Jersey calves
(the least susceptible breed) and the experiments were made in cool
weather in autumn. The limitation of the practice to the cool fall or
winter months renders the operation much more safe.
_b. Infecting Older Animals by a limited number of Ticks._ Yearling
Jerseys, Holsteins and Shorthorn were subjected to 25 to 50 ticks in
July, they showed only slight rise of temperature, and later resisted
the free exposure to tick infestation. It must be recognized that these
were still young animals, with presumably greater resisting power than
the mature, but on the other hand they were of the susceptible northern
herds, they were first infested in the hottest season, and the acquired
resistance appears to have been perfect throughout the succeeding
summer. The added precaution of subjecting them, in late autumn or
winter only, to the ticks raised in a warm room or thermostat, would add
greatly to the safety of the operation. After recovery from the effects
of the first crop of ticks, a second crop of 50 to 100 should be placed
on the skin so that the system may be thoroughly habituated to them and
the measure of resistance correspondingly strengthened.
This measure may be advantageously applied to valuable cattle that are
to be moved into the infecting territory, but it has serious drawbacks.
The relative strength of the poison introduced by the ticks to the
susceptibility of the animals on which they are placed, can never be
perfectly gauged, and a certain small but appreciable number of deaths
result from this first infesting. This has been observed in North and
South America, Australia, Roumania and Turkey. Again, the plan entails
the necessity for clean, non infected premises (lots or buildings) for
each fresh lot of cattle, as the places previously used are left in a
tick-infested condition, and are likely to furnish a dangerous excess of
ticks to any susceptible animal. The buildings could, of course, be
disinfected and purified, but this entails considerable expense.
_c. Infection by Graduated Injections of Blood Containing the
Pyroplasma._ Up to the present this is the most promising method of
securing resistance to the pyroplasma. It is advised to take the blood
from an immunized northern animal or from one indigenous to the infected
district. Such an animal is not, however, strictly speaking _immunized_.
It has acquired a _tolerance_ so that it is no longer in much danger of
succumbing to the pyroplasma, but it does not exclude the pyroplasma
from its system. The _micro-parasite_ is still found in the blood,
though mainly in the coccus-like form in the interior of the red
globules. The animal to be fortified against the disease is therefore
inoculated with the germ of the disease itself, though it may be, at the
time, in a somewhat inactive form. If, however, the inoculated animal is
specially susceptible, or if the dose is excessive, the disease is
produced in deadly form. The virulence is less in the case of blood
drawn from a northern animal just recovered from the disease, than from
an animal indigenous to the infected district, and which harbors the
pyroplasma, it may be in spore form (Lignieres), without showing obvious
disease. The former source of the blood is therefore the more desirable,
while the latter is the more easily obtained. The precaution, however,
should be adopted of reducing the dose when taken from an indigenous
animal. Another important precaution is to select the winter or cooler
season for the operation rather than the summer.
The animal which is to furnish the blood may be fixed in stocks, or held
with a bull ring, or it may be cast so that it can be kept still. The
hair is clipped or shaved from over the jugular vein in the upper third
of the neck and the surface is washed with soap and water and with a
five per cent. aqueous solution of carbolic acid. A thick cord inch (¼
inch) is tied tightly around the back part of the neck so as to compress
and raise the jugulars. With a sharp pointed bistuory sterilized by
boiling, a small incision is made through the skin, directly over the
centre of the jugular and a cannula and trochar ⅒th inch in diameter and
sterilized by boiling, is passed obliquely upward through the coats of
the vein and the trochar withdrawn. The blood flows through the cannula
and is received in a sterilized (scalded) glass beaker. The blood is
stirred slowly with a sterilized glass rod until all the fibrine has
coagulated when the latter is lifted out and the remaining liquid blood
is ready for use. The blood is injected with a hypodermic syringe which,
with its nozzle, has been thoroughly sterilized by boiling. The point
selected for injection is usually back of the scapula on the middle of
the chest. The skin is clipped or shaved, washed with soap, soaked in a
five per cent. carbolic acid solution, then pinched up, perforated with
the point of the bistuory, and with the nozzle of the syringe passed
through this wound the blood is injected into the subcutaneous
connective tissue. The slight wound may then be covered with tar or
collodion or merely left undressed. The mass of blood in the connective
tissue may be diffused through its meshes by rubbing so as to favor
absorption.
The dose of defibrinated blood employed is 5cc. if from an _immunized_
northern ox, or 3cc. or even 2½ cc. if from an indigenous animal. The
animal operated on should be in good health and condition, well fed, and
kept if possible in the shade, in a cool stable, or under trees.
In some respects it is preferable to operate on the animals before they
are moved from the north or other noninfected territory, but as there is
danger of infection in preserving and carrying the blood, the treatment
is more conveniently deferred until the animal reaches the infected
region where the blood can be had fresh. In such cases the animals
should be shipped in carefully disinfected cars, and before leaving they
should be liberally oiled or larded so that the ticks will not climb
upon them, in being led to their stable. They must be kept stabled until
the febrile effects of the injection have entirely passed, usually a
month or more.
_d. Injection of Blood from Bodies of the Ticks._ In view of the
difficulty of shipping infected blood without danger of contamination or
sepsis, and the occasional accidents that happen to animals injected
with such blood outside of the infected area, attempts have been made
with dried blood, or that charged with antiseptics (calcium oxalate), or
that had been frozen, but in every instance the virulence of the
pyroplasma was destroyed. Dalrymple and Dodson availed of the blood
drawn by mature ticks, which, in their blood-gorged condition, were
shipped to the points where the injections were to be made. The mature
ticks charged with blood were taken from infected indigenous cattle, and
at once shipped. On their arrival they were washed externally with a
mercuric chloride solution (1:1000) to destroy any adherent saprophytic
or other bacteria, mashed in a sterilized mortar, with a few cubic
centimeters of boiled water and the fluid portion drawn off and injected
subcutem, into the animal to be protected. From 3 to 12 mature female
ticks were used for each animal. The results were the same, only milder
than when the blood of the indigenous animal was used direct, and the
subsequent tolerance of the pyroplasma proved satisfactory.
It is difficult to explain the moderate effect of the considerable mass
of blood injected in such cases, as compared with the deadly effect of
the small amount that could come from the insertion of the rostra of
even 50 or 100 ticks. But perhaps the venomous saliva instilled in
concentrated form into the bites, protects the pyroplasma in the very
limited area, until it gains sufficiently in numbers and force to hold
its own even in the circulating blood.
_Limited Value of Artificially Induced Tolerance._ It must be added that
all these measures for securing a partial immunity in the individual
animal, and which enable us to safely introduce previously susceptible
cattle into an infected district, virtually imply the continuance of the
infection and infection bearer (boöphilus) for all time. They give no
promise of the extinction of the bovine infection at even a remote
future time, nor the abolition of the taxes for prevention, which must
oppress the southern cattle owner so long as the disease continues. They
are most valuable measures truly, but mere temporizing ones at the best,
and they could just as well give place to the more sanitary, economical
and statesmanlike measures for its radical extinction.
_Marketing of the Beef._ The piroplasma is not communicable to man, so
that the carcasses of well conditioned cattle, which bear the infection
need not be rejected as human food. It is only in severe and advanced
cases in which anæmia, emaciation and pallid innutritious muscles are
marked features, that the flesh is objectionable, and then only as being
somewhat lacking in nutriment and digestibility,—not because of
poisonous qualities. Danger of infection to cattle might be apprehended,
but, if used outside the infected area, the second condition of the
disease—the boöphilus—is lacking, while within the existing area of
prevalence of the fever, the propagation from the carcass to the animal
is infinitely less likely than from one live animal to its fellow.
_Federal Restrictions on Cattle within Infected Areas._ The orders of
the Secretary of Agriculture prohibit the removal of cattle from the
following states and territory into any states that extend northward of
the line indicated: California, Oklahoma, Indian Territory, Arkansas,
Tennessee, Virginia and the states south of these to the Gulf of Mexico.
Exceptions are made in the case of fat cattle, sent out of an infected
area, for immediate slaughter at the point of destination; conveyed in
cars or boats placarded as containing Southern cattle and receiving no
other; fed and watered enroute in yards that admit no local or other
cattle and which can be reached without passing over any highway or
unfenced open ground; and unshipped at their destination directly into
yards reserved for Southern cattle only and within the same enclosure as
the slaughter house. If reshipped the cars used must be subjected to the
same restrictions. The cars, boats, chutes, alleyways, pens and troughs
are to be disinfected by thorough cleaning; by saturation of all wood
work, etc., with a mixture of 1½ ℔s. lime, ¼ ℔. phenic acid and 1 gallon
of water, or ¼ ℔. chloride of lime in a gallon of water, or a jet of
steam under a pressure of 30 ℔s. to the square inch. The manure and
litter must be mixed with quicklime, or saturated with a 5 per cent.
solution of carbolic acid, or secluded in a well fenced enclosure from
February 1st to November 15th of each year. This is made the duty of the
stock yard companies.
Cattle may be freely moved north from the infected area at any time from
November 1st to December 31st, if inspected by an officer of the U. S.
Dept. of Agriculture and found free from infection.
Provision is also made for sending infected cattle northward at any
season, if they have been first dipped and pronounced free from the
disease by an inspector of the department.
Cattle from Mexico are admitted under analogous rules.