Sixty percent of infection diseases are zoonotic, meaning they spread from animals to people. Among the deadliest, and most difficult to eradicate, among these are viruses, which is why they're so often in the news. This summer, an Ebola outbreak claimed dozens of lives in Uganda and the Democratic Republic of the Congo. In the U.S., nine people camping in Yosemite National Park were infected with hantavirus and three died. We're also experiencing the nation's worst-ever outbreak of West Nile Virus: so far 4,249 cases have been reported.