It can be difficult to pinpoint when an invasive species makes landfall, but research scientist Andrea Egizi remembers when the Asian longhorned tick first crossed her radar. “It’s going to cost a lot of economic loss for producers,” says McCall, “whether or not they know it.” That contradicts the experience of McCall, the Granos’ veterinarian, who in 2020 encountered theileria in 40 of the Virginia farms she serves. In statements to MIT Technology Review, the National Cattlemen’s Beef Association, one of the largest cattle lobbying groups, said that occurrences of the disease remain rare in the United States. “You’re going to see deaths.”Īnd yet, while the US livestock industry has acknowledged theileria’s presence and the threat it poses, it seems to want to blunt concern. “I think in America, you’re going to see abortions,” he says. In the US, however, calving season can be year-round. Kevin Lawrence, an associate professor at Massey University who studies theileria in New Zealand, says that country has managed to avoid abortions because 95 percent of cows calve in the spring there, the same season he’s seen theileria infecting cows. In Japan and Korea, the combined loss is an estimated $100 million annually. In Australia, where the disease has been spreading since 2012 and now affects a quarter of the cattle, theileria costs the beef industry an estimated $19.6 million a year in reduced milk and meat yields, according to a 2021 paper. It can also cause anemia so severe that a cow will die. Theileria can cause cows to abort their fetuses. Some sale barns in Virginia saw the prevalence of theileria increase from two to 20 percent in just two years.
As it has spread in the US, so has theileria the disease has been found in cattle in West Virginia, North Carolina, Tennessee, Kentucky, Pennsylvania, and Kansas. The tick is native to Korea, China, Russia, and Japan. Theileria, which is in the same family as malaria, is being transmitted largely through the Asian longhorned tick, an invasive species first discovered in the US in 2017. If states can’t get the disease under control, then nationwide production losses from sick cows could significantly damage both individual operations and the entire industry. Researchers still don’t know how theileria will unfold in the United States, even as it quickly spreads west across the country. Livestock producers around the country are confronting this new and unfamiliar disease-if they can detect it in their herds at all-without much information. Cattle owners like the Granos are not alone.
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