The Centers for Disease Control and Prevention is working with public health, agricultural, and academic experts to understand the possible threat posed by the spread of the Asian longhorned tick (Haemaphysalis longicornis) in several U.S. states since its discovery in 2017, according to today’s Morbidity and Mortality Weekly Report. "The full public health and agricultural impact of this tick discovery and spread is unknown," said Ben Beard, Ph.D., deputy director of CDC's Division of Vector-Borne Diseases. "In other parts of the world, the Asian longhorned tick can transmit many types of pathogens common in the United States. We are concerned that this tick, which can cause massive infestations on animals, on people, and in the environment, is spreading in the United States."