Watch out for signs of Theileria orientalis
A new tick species has emerged, and it is costing cattle producers in more than one way. Ticks have a significant economic impact on the U.S. cattle industry, causing disease transmission, decreased gain, increased treatment expense, stress and reduced and milk production efficiency.
The Asian Longhorn Tick is originally from Eastern Asia and was first detected in a cow-calf herd in Virginia in 2017. It has since been detected in Arkansas in 2018, Missouri in 2023, Oklahoma in 2024. It was also recently discovered in Kansas in October.
Asian Longhorn ticks are able to reproduce without a male and can produce 1,000 to 2,000 eggs at a time. The females go through a process of essentially cloning themselves and one female tick has the potential to create an established population in a location in two to three weeks. It is a three-host tick which will spend 90% of its life off the host. The larvae, often referred to as seed ticks, feed on smaller animals. The nymph and adult stages target larger animals, including humans and cattle. The most common animals this tick has been found on include dogs, white-tailed deer, raccoons and cattle.
Theileria orientalis is a protozoan parasite carried in Asian Longhorn ticks. The protozoa causes disease by infecting the red blood cells. The immune system recognizes the infected cells as damaged and eliminates them which causes anemia. Signs and symptoms are similar to anaplasmosis: jaundice, fever and anemia. In mild cases cattle may exhibit symptoms such as an elevated temperature, depression and pale mucous membranes. In severe cases, cattle will show jaundice to the mucous membranes around the eyes and vulva, and severe depression. Pregnant animals may abort their calves and severe infestations can lead to death due to the stress of excessive blood loss and anemia.
There is no vaccine or treatment for Theileria as it is a protozoan and not a bacteria, therefore antibiotic treatment is not effective. As with anaplasmosis, the animal will become a lifelong chronic carrier of the disease. Because it is a bloodborne pathogen, there is a risk of transmitting the disease through needle use during vaccination. It can also be transmitted through biting insects such a biting flies and other ticks.
Kelly Loftin, an extension entomologist for the Division of Agriculture in Arkansas, said that a vaccine targeting five ticks–the lone star tick, gulf coast tick, American dog tick, black-legged tick and the Asian longhorn tick–is now available, but only through a veterinarian and approval from the Arkansas state veterinarian.
“The vaccination regime is an initial immunization followed by the administration of a booster 28 days later,” Loftin said. “This vaccine is designed to elicit production of antibodies that bind to proteins in the tick’s gut. It is hoped that this will prevent the tick from absorbing nutrients. And if fewer nutrients are absorbed, tick engorgement and egg production will be reduced.”
If you have cattle that are exhibiting signs of depression, late gestation abortion and general un-thriftiness such as rough hair coat, inspect those cattle for large infestations of ticks around the ears, armpits and tailheads. Contact your veterinarian who can provide guidance on the best tests for your cattle.
Stress plays a role in exhibiting symptoms as well where cattle can be carrying Theileria but will not start to exhibit signs until a stressful situation, such as calving, coming thru a hard winter, etc. Cattle can also show signs of a respiratory disease such as heavy breathing.
Management is key as there is no cure at this time, but supportive care can be implemented. Including minimizing stress, avoiding unnecessary handling, and ensuring access to feed and water. Monthly brush hogging of pastures and topical application of permethrin-based products can help reduce numbers of tick populations on the farm.
