A new tick-borne disease is killing cattle in the US

In the spring of 2021, Cynthia and John Grano, who own a cattle operation and sell performance horses in Culpeper County, Virginia, started noticing some of their cows slowing down and acting “spacey.” They figured the animals were suffering from anaplasmosis, a common infectious disease that causes anemia in cattle. But Melinda McCall, their veterinarian, had warned them that another disease carried by a parasite was spreading rapidly in the area.

After a third cow died, the Granos decided to test its blood. Sure enough, the test came back positive for the disease: theileria. And with no treatment available, the cows kept dying. In September, by which time the couple had already lost six cows and seven calves, Cynthia noticed a cow separated from the herd. She was walking up to it when it suddenly charged at her and knocked her over, breaking her shoulder blade. By that afternoon, the cow was dead.

Cattle owners like the Granos are not alone. 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. Researchers still don’t know how theileria will unfold in the United States, even as it quickly spreads west across the country. 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. Source: MIT Technology