Ames-based Harrisvaccines Inc. on Monday announced that the U.S. Department of Agriculture has granted conditional licensure of its Porcine Epidemic Diarrhea Virus Vaccine. The conditional license, the first granted since the initial outbreak in April 2013, will allow the company to sell the vaccine directly to veterinarians and swine producers who are battling the highly contagious swine disease, the company said in a release. Since entering the United States just one year ago, the virus has spread to nearly 30 states and throughout North America, causing the death of millions of piglets. The virus cannot spread to humans, but it has cost the pork industry and consumers hundreds of millions of dollars. Harrisvaccines developed a vaccine within weeks of the outbreak, and has sold nearly 2 million doses through veterinary prescriptions.