Foot-and-mouth disease (FMD) virus spreads much more aggressively in pigs than previous research suggests, according to a new study by U.S. Department of Agriculture (USDA) scientists. The study, recently published in Scientific Reports, shows that pigs infected with the FMD virus were highly contagious to other pigs just 24 hours after infection—long before showing any clinical signs of infection such as fever and blisters. Foot-and-mouth disease continues to be the most important foreign disease of livestock worldwide, said Jonathan Arzt, lead investigator and veterinary medical officer with USDA’s Agricultural Research Service (ARS). Although the United States has not had an FMD outbreak since 1929, this highly contagious viral disease, which is sometimes fatal, is still considered a serious threat to U.S. agriculture.