DES MOINES, Iowa (AP) — Federal agriculture officials say the virus that killed more than 8 million baby pigs in 2013 and 2014 likely came into the United States on reusable tote bags used in international trade. The U.S. Department of Agriculture also said Wednesday that the porcine epidemic diarrhea virus closely matched one found in China in 2012. The virus killed nearly 10 percent of the nation’s hog population, reducing pork supplies and causing record prices last year.