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.