Crawling threat: Asian longhorned tick threatens Oklahoma livestock
Wednesday, May 21, 2025
Media Contact: Sophia Fahleson | Digital Communications Specialist | 405-744-7063 | sophia.fahleson@okstate.edu
Along Oklahoma’s northeastern border, a new invasive threat is beginning to make its presence known. The Asian longhorned tick, once confined to distant regions, is crawling into the state, sounding alarms for livestock producers, said Jonathan Cammack, Oklahoma State University Extension specialist for livestock entomology and parasitology and assistant professor of entomology.
The Asian longhorned tick, or ALT, is native to East Asia and has spread globally through trade, Cammack said.
“It was first found in New Zealand and Australia about 100 years ago,” he said. “Since being established in the northeastern United States, it has been moving south and west.”
This past summer, ALTs were identified in northeast Oklahoma, making Oklahoma the 21st state to have identified the pest.
“The Asian longhorned tick is known as a three-host tick, meaning each of its life stages — larvae, nymph and adult — requires a blood meal, usually from a different host animal species,” Cammack said.
Typically, in a three-host tick life cycle, larvae feed on smaller creatures, such as rodents. Nymphs target slightly larger animals, like raccoons. Adults prey on even larger animals, such as cattle or deer, he added.
“With the Asian longhorned tick, all three life stages have been seen feeding on the same species or individual,” Cammack said. “In the case of livestock, that could be a cow.
“We could have instances where as many as 1,000 of these ticks could be feeding on a single animal at a given time,” he continued. “That could result in the animal dying due to blood loss.”
Beyond feeding habits, the ALTs’ ability to reproduce can threaten the livestock industry, Cammack said.
With a single tick introduction, the population can be established at a quick rate, said Dr. Rosslyn Biggs, clinical assistant professor of veterinary medicine at OSU. Biggs also serves as an OSU Extension beef cattle specialist and veterinarian.
“The Asian longhorned tick can reproduce without mating through a process known as parthenogenesis, meaning they do not need a male to reproduce,” Cammack said.
By eliminating the need to find a mate, this reproductive strategy allows the population to grow faster, he said.
The small size of the ALT also contributes to the challenge of controlling its spread, Cammack said.
An adult ALT is easy to overlook, measuring from 3 to 5 millimeters, similar to the size of a sesame seed, Biggs said.
In addition to being small, the ALT can transmit a disease that affects livestock and presents challenges for livestock management, Biggs said.
The ALTs will parasitize multiple species, including, cattle, sheep, goats, horses, chickens, dogs, cats and multiple wild animals, she said.
“The tick can transmit a protozoan pathogen known as Theileria orientalis, specifically the Ikeda genotype,” Cammack said. “Since it is a protozoan and not a bacterium, it cannot be treated with antibiotics.”
ALTs can transmit this pathogen at a high rate, essentially impacting the livestock industry overall, he added.
T. orientalis has similar clinical signs to anaplasmosis, Biggs said.
“However, it has a different distribution, meaning that it has a tendency to impact young animals,” she said. “Anaplasmosis, on the other hand, typically affects older animals.”
Symptoms of T. orientalis include anemia, weakness and incoordination, which are also seen in anaplasmosis, Biggs said.
“We could also potentially see neurological signs due to decreased oxygen levels from reduced blood volume,” she said.
“The mortality rate for Theileria is variable,” she added. “In some instances, it has been as low as 3% and as high as 90% in herds that were infested.”
Oklahoma has not been exposed to T. orientalis Ikeda, so the state’s cattle population is naïve to the disease, Biggs said. No labeled treatment is available for the disease, which limits management options, she added.
“My recommendation for Oklahoma producers is if they suspect anaplasmosis and the cow is not responding to treatment, they should consider sampling for Theileria orientalis, specifically the Ikeda strain,” Biggs added.
To reduce the risks associated with T. orientalis, producers should implement preventative measures, she said.
The ALT is expected to remain a concern in Oklahoma, so treating the animals and environment is important, said Justin Talley, professor and head of the OSU Department of Entomology and Plant Pathology.
“Pasture rotation and patch burning can significantly reduce the tick population,” Talley said.
Implementing patch burning has been shown to reduce tick populations by more than 80%, Cammack said.
“It stands to reason that we could see the same impact of patch burning on this pest species, but we don’t have that data yet,” he said.
Chemical products labeled for tick control are effective against the ALT, Cammack said.
“If producers are concerned about their herds, they should start putting cattle through the chute,” Talley said. “When checking for ticks, inspect the head, neck, flank, tail and sometimes the back.”
If ticks are found on the animal and ALTs are suspected, collect a sample, and consult your veterinarian or a local OSU Extension educator.
The state veterinarian is monitoring reports of ALTs closely, Biggs said.
Producers should remain vigilant in monitoring their herds, Talley said. By taking proactive steps now, producers can protect their cattle and minimize the impact of this new invasive species, he added.
Would You Help with OSU Research?
Oklahoma State University College of Veterinary Medicine has an ongoing, internally funded research project focused on the spread of the Asian longhorned tick, Theileria orientalis, and anaplasmosis in cattle, led by Drs. Ruth Scimeca, John Gilliam and Rosslyn Biggs.
The team is seeking 20 to 30 cattle operations in Oklahoma and surrounding states to participate in the project.
Producers, in collaboration with their veterinarians, can submit up to 20 blood samples per operation for testing. They may also submit up to 15 ticks, if collected.
All laboratory testing and shipping supplies are provided at no cost to the participants. Producers and veterinarians will receive reports on the results of the testing.
“We are trying to assess if this tick has potentially marched further west,” Biggs said.
“Hopefully, this will lead to a better understanding of environmental factors, wildlife populations and future research opportunities,” she said.
Story by Katey Brickman | Cowboy Journal