Texas Fever

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TEXAS FEVER
From 1865 to present
What is Texas Fever?
• In June 1868 a fatal outbreak was
reported among cattle in Illinois.
• It was characterized by high fever, anemia,
emaciation, and diarrhea.
• NINE OUT OF TEN cattle who got the
sickness died.
Why not Illinois Fever?
But if the outbreak occurred in Illinois, why
was it called Texas Fever?
The Mystery
Settlers quickly discovered that whenever
healthy Texas longhorns mixed with midwestern cattle from Kansas, Missouri,
Illinois, and Oklahoma, the mid-western
cows became ill with the disease.
But WHY was this
Important?
Cattle Drives 101
• In 1865 there was a great demand for
beef on the eastern coast of the US where
supplies of cattle were severely depleted
from the recently ended Civil War.
• Meanwhile, there was a plentiful supply of
cheap cattle in Texas and other
southwestern territories.
Cattle Drives 101
• Texas cattle ranchers and entrepreneurs
began hiring many cowboys to round up
and brand the unclaimed cattle and to
move them to the eastern markets.
• Unfortunately, most of the Texas
rangelands were isolated from any easy
transportation to the east.
Cattle Drives 101
• The task of the cowboy was to take part in
cattle drives where cattle were driven from
Texas to the railroad cow-towns.
Cattle Drives 101
• Between 1866 to 1895 some 10 million
cattle were taken to the railroad cow-towns
by way of cattle trails. These trials were
over 1,000 miles long and would take
between 12 and 16 weeks to complete.
The Disagreement
• To protect their own cattle from Texas
Fever, states on the cattle trail, such as
Kansas and Missouri, closed their borders
to Texas cattle.
• The Texans became angry and attempted
to defy the quarantines. They claimed that
the disease could not possibly come from
their cattle because they did not get sick.
Because the Texas longhorns did not seem
to be infected by the disease, many
people developed a great fear and respect
for the Texas cattle. Even some of the
Texas cowboys who herded the cattle
north refused to slaughter the animals.
To the Courts
In 1877, Texas took their battle to the U.S.
Supreme Court and won. The court declared
the laws of Kansas and Missouri closing their
borders unconstitutional as they hindered
interstate commerce.
The End of the Cattle Drives
However, the damage had
already been done. Once
the states closed their
borders, the era of the
cattle drives was
effectively ended, as
many of the main trails,
including the Shawnee
and Chisholm trails, were
never to be used again.
Inspection Stations
• But now that the
Supreme Court allowed
Texas longhorns to be
sent north, mid-western
cows started becoming
sick again.
• The states tried to set up
inspection stations at
border crossings, but they
were easy to avoid
because of the widely
unsettled state borders.
Bureau of Animal Industry
So under pressure from the states, the
federal government created the Bureau of
Animal Industry in 1884, with the intent to
regulate cattle traffic and suppress bovine
diseases.
Bureau of Animal Industry
The Bureau of Animal
Industry employed
many bright scientists
to try and discover the
cause of this
mysterious illness.
What was this mysterious illness?
Since the midwestern cows became sick
after being mixed with Texas longhorns or
grazing in the pasture soon after they were
gone, many people thought that the
longhorns generated toxic waste that killed
the other cows.
Louis Pasteur
However, another idea
stemmed from the
experiments of Louis
Pasteur, known for
his demonstration of
germ theory of
disease.
The Discovery
• This led to the
discovery in 1893 by
two scientists
Theobald Smith and
Frederick Kilborn who
found the microscopic
organism responsible
for Texas Fever, a
protozoan they
named Babesia
bigemina.
The Workings of the Parasite
It was discovered that the parasite first
enters the infected animal’s bloodstream,
and then inhabits and destroys the red
blood cells.
New Name for an Old Disease
The new name of Texas Fever became
bovine babesiosis, after the protozoan that
causes it. This is the current name that is
still used around the world.
The whole mystery was not solved
yet
How did the
protozoan infect
the cattle?
A Clue
• One important clue was when the Texas
longhorns spent the winter in the north, they no
longer infected the mid-western cattle.
TICKS!
This led many people to
suspect that cattle
ticks were involved
somehow.
They were correct!
• The same scientists that discovered the
protozoan found the vector to be cattle
ticks.
• The ticks sucked blood from an infected
animal, dropped in the grass, laid eggs
and hatched young ticks harboring the
protozoan, ready to infect more cattle.
Many settlers thought that the longhorns poisoned the
grass, which was partially correct. The ticks dropped off
of them and hid in the grass, ready to infect another
animal.
Ticks as the Vector
• But when the Texas longhorns spent the
winter up north, the ticks died from the
colder temperatures.
• And without the vector, there was no
disease!
Blood-sucking Insects
• This was a very important breakthrough
because it marked the first time a bloodsucking insect transmitted a disease.
• This later led to the discovery of
mosquitoes as vectors for malaria and
yellow fever.
But this was STILL not the whole story
Why were the Texas longhorns not
affected by the cattle ticks?
Only in modern times can we
understand why
• It turns out that the Texas longhorns had
developed an immunity to the parasitic
protozoan.
• When the calves were born, they had a
natural partial resistance to the infection
from antibodies in their mother’s milk.
Texas Longhorns had Immunity
The calf would only suffer a mild non-fatal
attack, and then develop resistance to the
parasite. When the calf became an adult
cow, it maintained its immunity by
constantly becoming re-infected by tick
bites, remaining a carrier of the disease.
But non-Texas cattle did not
When a cow from the
mid-west was
introduced to the
infected ticks, they did
not have any
immunity to the
parasite they
harbored, and the
illness quickly
became fatal.
Breaking the Transmission
After discovering that
without the ticks the
illness disappeared,
the Texas cattle were
dipped in arsenic,
beginning with the
first dipping vats on
the King Ranch in
1903.
Vaccines
When Northern cattle were brought in to Texas,
they could be immunized with small amounts of
blood from infected animals, a type of vaccine
known as a live vaccine.
Finally!
Even with all of these efforts, the disease
was not eradicated in the United States
until 1942.
In modern times…
Cattle fever in the rest of the world
The disease still inflicts millions of cattle all
over the world, in places such as
Southern Europe, South America, South
Africa, the West Indies, and Australia.
A New Threat from an Old Enemy
The disease is also starting to come back
to Texas. Although Texas has gotten rid of
the ticks, Mexico still has problems with
them. Because of our increased trade
relations with Mexico, the disease is once
again threatening our cattle population.
“Tick Riders”
To maintain the safety
of our Texas cattle,
Texas officials have
created a “permanent
quarantine zone” on
the border of the Rio
Grande, patrolled by
60 USDA “tick riders”
on horseback who
apprehend and
inspect stray livestock
in the zone.
Safety of our Cattle
• Texas Animal Health Commission field
personnel also are trained to collect and
identify ticks, as there is always a chance
that fever ticks could be carried northward,
or other dangerous foreign ticks could be
introduced from other parts of the world.
Conclusion
• Texas cattle fever nearly single-handedly
ended the cattle drives of the 19th century.
Even with extensive efforts of eradication,
the parasite still infects millions of cattle
around the world. However, through
solving this mystery, we have gained
knowledge about the source of disease,
leading to the eradication of many other
diseases.
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