Asian longhorned ticks continue to spread in Virginia, causing cattle worries

As Asian long-horned ticks continue to spread throughout Virginia and the United States, scientists are racing to understand how the species is expanding so fast and how they can keep a virulent parasite carried by the ticks from infecting herds of cattle.

“There’s a geographic niche for these ticks, and we are reaping that,” said Dr. Kevin Lahmers, associate lab director of Virginia Tech’s Animal Laboratory Services and a professor with the Virginia-Maryland College of Veterinary Medicine. But, he added, “We still have a lot to learn.”

Asian long-horned ticks have likely been in the U.S. since 2010, but seven cattle deaths in Virginia’s Albemarle County in 2017 found the species was carrying a new threat to livestock: a virulent form of the Theileria orientalis parasite, which can cause a disease known as theileriosis characterized by anemia, fever, jaundice, respiratory problems and weakness in cattle. In some cases, cows become so depleted that they spontaneously abort fetuses; in other cases, cattle die. Research has estimated this particular form of Theileria, known as the Ikeda genotype, causes mortality rates between 1% and 5%.