As Asian Longhorned tick (ALHT) infestations and theileriosis cases climb across the U.S., the message from veterinary and entomology experts is clear: stay vigilant, but don’t panic.
During a Drovers exclusive round table on Farm Journal TV, Cassandra Olds, Kansas State University Extension entomologist, and Dr. John Currin, Virginia Tech extension veterinarian, provide a management blueprint for producers, using a real-time Tennessee outbreak to illustrate how to handle a worst-case scenario.
Unlike most ticks that rely on weather-dependent mating cycles, the ALHT is a biological outlier. A single female can clone herself without mating, creating thousands of offspring. This unique ability gives ALHT populations the explosive growth potential of a fly outbreak rather than a typical tick season — making rapid response and strategic management essential.
ALHTs carry Theileria orientalis, a protozoan parasite that infects red and white blood cells, causing anemia and, in severe cases, death. Bovine theileriosis is the disease caused by Theileria orientalis.
Travis Mundy’s account is the emotional core of the webinar — he laid hands on a heifer Saturday, saw nothing wrong Monday, and found her dead by Tuesday noon. They lost another one down that day and tried to save her, but lost her too.
While Mundy’s story is dramatic, it’s also a useful case study in how this invasive tick and the parasite it carries can ambush even well-managed herds.
Here are five key ALHT and theileriosis facts discussed by Olds and Currin during the round table:
1. Asian Longhorned Tick Reproduces Explosively Without Mating.
Olds explains the biology is what makes ALHT uniquely dangerous compared to native ticks.
“The key difference between this tick and our native tick species is that this tick can reproduce without mating, so a female tick will just make little clones of herself,” she explains. “This tick really has the potential to behave in a more explosive way, like a fly would.”
Olds also stresses this year’s tick pressure — ALHT and all ticks — is the result of several years of weather, not just one bad season. She points out the tick’s life cycle takes two to three years, with each stage feeding and then overwintering.
Two big climatic threats to ticks are drying out and temperature extremes. Olds says ticks do best with good moisture and high humidity — especially in leaf litter, tall grass and shaded areas.
Very mild winters and little snow mean fewer ticks are killed each year. More ticks survive into spring, so each year starts from a higher baseline. That means conditions over multiple winters and springs stack up to create today’s populations.
2. Most Theileria-Infected Cattle Show Zero Symptoms — Living With the Organism.
Currin lays out the Theileria picture clearly: “The vast majority of cattle, 99% of the cattle that are infected, don’t show clinical signs of a problem. But in a small percentage of animals they will develop severe anemia, and in some cases die.”
He also flagged a recognized risk group — calves. He stressed to Mundy what he needs to worry more about than cows aborting is the 2-month-old calf.
A key strategy in endemic areas is recognizing that total eradication of the organism within a herd may not be desirable. Low-level infection can actually provide a form of natural immunity, which Currin explains prevents future clinical disease.
“We actually don’t want animals completely clear of this organism if they’re in an endemic area, because that will just set them up to potentially get reinfected,” Currin says. “It appears that becoming infected and living with low levels, this organism likely protects that animal from having clinical disease almost all the time in the future.”
Both Currin and Olds say basic herd health is important to support immunity and to protect a herd from bovine theileriosis.
“All the best management practices that we have always recommended for livestock — providing good mineral nutrition, providing good protein and energy nutrition for those animals to maximize their immune system function, is likely important to try to help minimize problems,” Currin says.
Olds adds, “Making sure that nutrition is good, preventative measures are good, and then, for those who are receiving those animals, making sure that we’re keeping those animals healthy, happy, eating and low-stress. I think that goes a long way in mitigating some of the stress‑related responses we see in these cattle.”
3. No Food Safety Risk — But Resistance Management is a Real and Growing Concern.
Both experts emphasize beef remains safe, while warning producers against overcorrecting with dewormers.
“There is absolutely no concern on consuming our beef product based on either the tick or the Theileria organism itself,” Currin explains.
The good news about ALHT is that most common ectoparasite products still kill it. The bad news, say experts, is how easily fear can push producers into overusing the wrong tools.
“Anytime you use an insecticide, you’re breeding an insecticide-resistant population,” Olds says. “We need to be really, really careful, especially when we start having situations like these large infestations.”
Olds admits the best thing to kill ALHT is a pyrethroid spray that drenches the animals’ coats.
“Ticks are very susceptible to pyrethroids,” she says, noting that whole‑body sprays work better than pour‑ons in heavy infestations.
“People are getting a little bit scared and then they’re treating their whole herd with, for example, an ivermectin injectable, and this is bad from the selection of gastrointestinal nematodes,” she explains. “We don’t want to drive resistance in that population.”
4. Timing Treatment is Still Trial-And-Error, Even for the Experts
The experts agree how early-stage the science behind preventing ALHT infestations is and encourage producers to use a wait-and-see approach instead of mass applications.
“I think a better approach would be to play it by ear, and then wait and see how it goes, and then apply a product, rather than thinking about it like, okay, what can I apply,” Olds says.
Currin says the industry is 10 years away from having a reliable timing recommendation.
“The challenge is marrying up the timing of when you administer the product and when this tick swarming is,” he explains. “We don’t have the data. I hate to say this, but just being in those cattle regularly, and noticing that they’re starting to get ticks, and then apply. That is our current best recommendation.”
If using ectoparasite controls — treatments for ticks and flies — the experts encourage producers to move beyond anecdotal evidence and actually “gauge” the results to identify potential resistance or application errors.
“Look at the animals beforehand and get sort of a rough idea of where you’re sitting,” Olds stresses. “Then after the product has been used, take another look. Unless you’re sort of having some gauge of before and some gauge of after, it’s really hard to say whether a product works.”
5. Pasture Management May Matter More Than Any Treatment
“One of the current recommendations from a tick standpoint is to fence the cattle away from water, away from shade and trim the pastures really short — and that certainly makes sense from a tick standpoint, but from a beef production standpoint, maybe not quite as good,” Currin says.
Pasture management strategies do vary by region. Olds says prescribed burning works in Kansas to reduce tick load but she does not encourage that practice for all areas.
“I think clipping the pastures and especially in those wet, damp areas really helps,” Mundy says, comparing tick loads his herd has experienced in different locations.
The experts emphasize the spread of ALHT and Theileria is a serious concern for the cattle industry; they suggest the goal is proactive management and community communication rather than a reactive or panicked response.
“We’ve got to be vigilant, but not panic, and we’ve got to move forward as a community,” Olds summarizes. “We’ve got to look out for our neighbors, look out for ourselves, and just, keep communication open.”
Farm Journal TV hosted this exclusive roundtable about the pest: watch it for free here and you can sign up for more exclusive content.
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