Researchers with the University of Arkansas System Division of Agriculture are monitoring the spread of the Asian longhorned tick, an invasive species that poses a significant threat to cattle in the state.
The Asian longhorned tick (Haemaphysalis longicornis) was first confirmed in the United States in 2017, though earlier samples collected in New Jersey and West Virginia in 2010 were initially misidentified as rabbit ticks. The species carries the pathogen Theileria orientalis, with two genotypes — Ikeda and Chitose — confirmed in Arkansas.
The ongoing study to determine the prevalence of both the tick and the pathogen in Arkansas cattle is funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture.
So far, the tick has been confirmed in at least 20 states, primarily in the eastern U.S., with its range extending as far west as eastern Oklahoma. In Arkansas, it has been found in Benton, Boone, Independence, Newton, Searcy, and Washington counties. The Theileria pathogen has been confirmed in cattle in Arkansas, Baxter, Boone, Carroll, Lonoke, Marion, Searcy, and Washington counties.
Symptoms Resemble Anaplasmosis
Kirsten Midkiff, extension animal health and wellbeing specialist for the Division of Agriculture, said cattle infected with Theileria show symptoms similar to anaplasmosis, a bacterial disease familiar to many Arkansas producers.
“We’ll see weight loss, suppression of milk production, loss of appetite, anemia, and reproductive problems like abortions,” Midkiff said. “You may also see jaundice, weakness or reluctance to move, and even death in some cases.”
Although the tick poses no known threat to humans, its infestations can be severe, with host animals sometimes carrying hundreds or thousands of ticks. To date, no extreme infestations have been documented in Arkansas, but researchers have found the tick on 44 species of mammals and birds.
Other Transmission Risks
Theileria can also be transmitted through biting flies, other tick species, and contaminated needles. Midkiff urged producers to use clean needles during vaccinations to prevent spreading the pathogen between cattle.
Currently, there is no treatment for Theileria in cattle. USDA data shows mortality rates range from 1 to 5 percent but can reach 50 percent in severe cases.
Vaccine and Control Measures
A vaccine targeting five tick species — including the Asian longhorned tick — is now available, but only through veterinarians and with approval from the Arkansas State Veterinarian. The vaccination involves an initial dose followed by a booster 28 days later. Researchers hope the vaccine will reduce tick feeding and reproduction, though efficacy data is still being studied.
For now, producers can find tick control recommendations in the Division of Agriculture’s publication MP144, Insecticide Recommendations for Arkansas.
