By Barry Whitworth, DVM

Over the past few years, Theileria orientalis has been detected in cattle in Oklahoma. Early cases were primarily diagnosed in adult cattle. However, more recent cases in Oklahoma have been identified in stocker cattle. All cattle producers should be familiar with the clinical signs of this disease and observe their cattle daily for any signs of trouble.

In the United States, the first case of theileriosis was identified in Virginia in August 2017. These cattle exhibited clinical signs of weakness and anemia. An initial diagnosis of anaplasmosis was made. Blood samples from the animals were tested for Anaplasma, Babesia, and Leptospira. Test results were negative for all three; however, a blood protozoan was detected. This organism was identified as T. orientalis genotype Ikeda. Since this initial herd outbreak, the organism has been detected in several states.

Cattle infected with and showing illness from T. orientalis genotype Ikeda may exhibit clinical signs such as fever, weakness, anorexia, and exercise intolerance. If forced to move, affected cattle may stagger and gasp for air. If stressed excessively, they may collapse and die. Upon examination, the gums, eyes, or vaginal mucosa may appear pale (white) or yellow in color. Reproductive losses, including stillbirths and late-term abortions, may occur, along with a reduction in milk production.

Clinical signs reported in adult cattle in Oklahoma include anemia, sudden death, weight loss, abortion, failure to thrive, and failure to calve. In stocker cattle, weight loss, anemia, poor performance, and sudden death have been reported.

Because Anaplasma marginale and T. orientalis genotype Ikeda produce similar clinical signs, distinguishing between the two can be challenging.

One notable difference is that clinical signs are more commonly observed in young cattle infected with T. orientalis, whereas this is less common in cattle infected with A. marginale. Additionally, cattle with anaplasmosis often display aggression, whereas those with T. orientalis genotype Ikeda typically do not. A laboratory test is required to definitively differentiate between the two diseases.

Haemaphysalis longicornis has been identified as a possible vector of T. orientalis genotype Ikeda. In 2017, the United States Department of Agriculture’s (USDA) National Veterinary Services Laboratories (NSVL) confirmed the presence of H. longicornis, commonly referred to as the Asian longhorned tick (ALT) or bush tick. In efforts to determine how the tick arrived in the United States, USDA officials discovered it had been present in West Virginia as early as 2010. The tick has now been confirmed in at least 26 states, including Oklahoma. There is also some evidence suggesting additional insect vectors may transmit T. orientalis genotype Ikeda. Needle transfer is another possible route of transmission.

The ALT has been identified in Craig and Mayes counties in Oklahoma. This tick thrives in areas with high humidity, such as wooded regions, brush, or tall grass. Ticks are often found where large numbers of wildlife congregate, such as along deer trails. Producers seeking more information about the ALT can visit the USDA website at: https://www.aphis.usda. gov/livestock-poultry-disease/ cattle/ticks/asian-longhorned.

In other countries, treatments have been developed for T. orientalis. Unfortunately, no approved treatments are currently available in the United States, and no vaccines exist for this disease. The best defense is prevention: purchasing cattle free of the organism, avoiding blood transfer between animals, and implementing effective tick control measures. Producers should purchase cattle from reputable sources. Instruments should be cleaned between animals during procedures such as castration or dehorning, and needles should always be changed between animals. External parasites must be controlled using appropriate insecticide treatments. In addition to insecticides, pasture management strategies—such as rotation to avoid wooded or brushy areas where ticks thrive—are important. Patch burning may also help reduce tick populations.

Theileria orientalis remains a concern for some cow/calf and stocker producers in Oklahoma. Producers seeking more information about T. orientalis genotype Ikeda should contact their local veterinarian or Oklahoma State University County Extension Agriculture educator.

References Hammer, J. F., Emery, D., Bogema, D. R., & Jenkins, C. (2015). Detection of Theileria orientalis genotypes in Haemaphysalis longicornis Ticks from Southern Australia. Parasites & vectors, 8, 229.

Oakes, V. J., Yabsley, M. J., Schwartz, D., LeRoith, T., Bissett, C., Broaddus, C., Schlater, J. L., Todd, S. M., Boes, K. M., Brookhart, M., & Lahmers, K. K. (2019). Theileria orientalis Ikeda Genotype in Cattle, Virginia, USA. Emerging infectious diseases, 25(9), 1653–1659.

Spickler, Anna Rovid. (2019). Theileriosis. Retrieved from http://www.iastate.edu/DiseaseUbfi/factsheets.php.

Watts, J. G., Playford, M. C., Hickey, K.L. (2016). Theileria orientalis: A Review, New

Zealand Veterinary Journal, 64:1, 3-9.

By Ann Asher

Then there are the diseases and pests that younger generations have only read about.

For decades, New World screwworm belonged in that second category. Older ranchers remembered the days when a simple branding wound or a newborn calf’s navel had to be watched closely because it could attract one of the livestock industry’s most destructive pests. Veterinarians still taught students how to recognize it, but for many producers, screwworm was something that had been conquered long before they ever worked their first set of cattle.

This summer, that changed. On June 3, 2026, the U.S. Department of Agriculture confirmed New World screwworm in a calf in South Texas, marking the parasite’s return to the United States after decades of successful eradication. While Oklahoma has not reported any confirmed cases, the discovery has ranchers across the Southern Plains paying close attention. The concern isn’t just where screwworm is today, but where it could be tomorrow.

Unlike the common maggots that feed on dead tissue, New World screwworm larvae feed on living flesh. Adult female flies are drawn to fresh wounds and natural body openings, laying hundreds of eggs at a time. Within hours, the larvae hatch and begin burrowing into healthy tissue, enlarging the wound as they feed. Left untreated, an infestation can become life-threatening.

There are some livestock problems that today’s ranchers know by heart. Pinkeye. Foot rot. Horn flies. Internal parasites. Most producers have dealt with them at one time or another.

The list of potential hosts is long. Cattle, horses, sheep, goats, pigs, dogs, wildlife and, in rare cases, people can all become infested. Even relatively small injuries—a wire cut, a tick bite, a branding wound, a castration site, a dehorning wound or a newborn calf’s healing navel—can provide an opportunity for the fly.

Fortunately, today’s producers have one advantage their grandparents often did not: they know what they’re looking for.

A wound that continues to grow instead of heal should never be ignored. Bloody or watery discharge, a strong foul odor, swelling, pain, visible larvae and unusual behavior such as excessive licking, head shaking or isolation from the herd all warrant a closer look. While these signs can indicate several different conditions, they should also prompt producers to consider the possibility of screwworm and contact their veterinarian immediately.

The return of screwworm has also reminded many people of one of agriculture’s greatest success stories.

During the mid-1900s, New World screwworm cost American livestock producers millions of dollars each year. Rather than relying solely on insecticides, scientists developed what became known as the Sterile Insect Technique. Millions of sterile male flies were raised and released into affected areas. Female screwworm flies mate only once during their lifetime. When they mated with sterile males, no offspring were produced. As generation after generation failed to reproduce, screwworm populations steadily declined until the pest was eliminated from the United States and later pushed farther south through Mexico and much of Central America.

That same strategy is once again leading the response.

Federal and state animal health officials have increased surveillance in affected areas, established movement controls where necessary and resumed sterile fly releases to prevent the pest from becoming established. Veterinarians, livestock markets and producers are all part of the early detection system, with every suspicious case helping officials determine where additional monitoring may be needed.

For Oklahoma producers, the message is one of awareness rather than alarm.

As of this writing, no cases have been confirmed in Oklahoma. Even so, Oklahoma shares a long border with Texas, and livestock routinely move throughout the region for sales, breeding, shows and grazing. That makes vigilance especially important during fly season.

Routine herd checks have always been one of the best management tools available, and they are even more valuable now. Fresh wounds should be treated promptly and monitored until they heal. Newly branded or processed cattle deserve extra attention, as do newborn calves, horses with injuries, sheep after shearing and any animal recovering from surgery or trauma. Wildlife can also serve as hosts, making complete prevention impossible, but early detection can make all the difference.

If producers suspect screwworm, they should avoid simply treating the wound and moving on. Instead, they should contact their veterinarian or the Oklahoma Department of Agriculture, Food and Forestry so the case can be evaluated and, if necessary, samples collected. Rapid reporting is one of the most effective tools available for limiting the spread of the pest.

Perhaps the most encouraging part of this story is that agriculture has faced this challenge before—and won.

The same science that eliminated New World screwworm from the United States decades ago is once again being deployed. Researchers understand the insect’s life cycle. Veterinarians know what to look for. Producers are better connected than ever through Extension services and state animal health agencies.

Screwworm may have returned to the United States, but so have the tools that defeated it the first time.

For Oklahoma livestock producers, the best response is also the simplest: keep an eye on your animals, don’t ignore wounds that aren’t healing, and report anything that doesn’t look right. When it comes to screwworm, finding one case early is far better than finding many too late.

Few inventions changed the face of American agriculture as much as the steel plow. To settlers moving westward in the 19th century, the fertile black soils of the Midwest and Great Plains looked promising, but farming them proved nearly impossible with the tools of the day. Wooden and cast-iron plows stuck, broke, or clogged in the thick sod. That all changed in 1837 when a Vermont-born blacksmith named John Deere hammered out a new kind of plow with a polished steel blade. His design cut the earth clean, shed the sticky prairie soil, and opened vast new regions – including Oklahoma and Texas – to farming.

Early plows had served farmers in the eastern United States well enough. Wooden moldboards or cast iron blades could turn light, sandy soils. But when settlers reached the tallgrass prairies, they met a stubborn enemy: a dense mat of roots, sometimes several inches thick, holding sod together like a woven carpet. Trying to pull a wooden or iron plow through it was slow, exhausting work. Soil clung to the blade, forcing constant stops to scrape it clean. Even strong teams of oxen could only manage short furrows before the plow failed.

John Deere, working in Grand Detour, Illinois, spotted a solution. Drawing on his blacksmith skills, he repurposed a broken saw blade and shaped it into a curved plowshare. Unlike rough iron, the highly polished steel let the sticky prairie soil slip cleanly off with each pass. His first prototype, built in 1837, was followed by commercial models within a few years. Farmers who tested them quickly spread the word.

By the 1840s, Deere’s “self-scouring” plows were in high demand. They allowed a farmer to cut deep into prairie sod, overturning wide furrows that aerated the soil and prepared it for planting. What had once taken days of backbreaking work could now be done in hours. The barrier of tough sod, which had limited settlement and discouraged cultivation, was broken.

As thousands of families streamed westward after the Civil War, they carried Deere plows – or imitations of them – on wagons and trains. By the time Oklahoma was opened to settlement in the late 1800s, the steel plow was already a fixture on homesteads. In North Texas, it helped transform open prairie into wheat, corn, and cotton fields.

From Tool to Transformation

The steel plow was not just a better blade; it was a turning point in the history of American agriculture. By making prairie soils farmable, it opened millions of acres to cultivation. Wheat and corn production surged, fueling both local economies and national markets.

In Oklahoma and Texas, the plow shaped settlement patterns. Towns sprang up around fertile farmland, and railroads laid lines to carry grain and cotton to distant buyers. Farmers who once raised just enough for their families began producing surpluses. The steel plow helped push the U.S. toward becoming a global agricultural power.

But the story was not without consequences. Breaking the sod meant breaking the natural cover that had held prairie ecosystems together for centuries. Grasslands that had supported bison and protected soils were replaced with monoculture crops. While the plow unlocked prosperity, it also set the stage for soil erosion and, decades later, the Dust Bowl of the 1930s.

Culturally, the steel plow became a symbol of progress. John Deere himself built a company that still bears his name, and the green-and-yellow brand became synonymous with farming. Homesteaders told stories of how the polished blade “sang through the sod,” making it possible to turn dreams into harvests.

Even today, antique Deere plows stand in museums, barns, and pastures as reminders of the first great tool of prairie agriculture. Many families keep them as heirlooms, rusted but intact, a testament to the determination of those who first broke the land.

The steel plow was more than a piece of iron and wood. It was a key that unlocked the Great Plains, shaping the settlement of Oklahoma, Texas, and much of the West. It allowed farming where farming once seemed impossible, bringing prosperity and growth, but also altering landscapes in ways that would echo for generations.

Like barbed wire and windmills, the steel plow is part of the story of how ingenuity and necessity met on the frontier. It reminds us that every invention carries both promise and responsibility, and that the land we farm today still bears the marks of tools first forged nearly two centuries ago.

References

Deere & Company. Company History. https://www.deere.com

Smith, Philip. The Emergence of Agriculture in the Great Plains. University of Oklahoma Press, 1986.

Library of Congress. John Deere and the Invention of the Steel Plow.

National Museum of American History. “Plowing the Plains.” Smithsonian Institution.

Oklahoma Historical Society. Agriculture and Settlement in Oklahoma.