Three new cases of Ebola have been reported in Liberia. Reuters reports that despite the declared end to the Ebola outbreak in that country in May, the medical community is speculating that a cluster of infectious carriers somehow survived longer than was previously believed possible, or that there is a previously unknown means of transmission. Health officials "were monitoring 175 people believed to have come into contact with the three cases, though none had yet exhibited symptoms of the disease." The report notes that "A U.S. military operation aimed at helping Liberia's government counter the outbreak has mostly withdrawn. But the Centers for Disease Control and Prevention, a U.S. health body, said it was working with local authorities to study the origin of the cases and stop the virus spreading."