The spread of a flesh-eating ulcer in parts of Australia is being described as a "rapidly worsening epidemic" and, to make matters worse, researchers say they don't know exactly where it comes from or how it is transmitted.Known as Buruli ulcer, the infectious disease initially appears as a small red lump that resembles a pimple or insect bite, Daniel O'Brien, deputy director of the department of infectious diseases at Barwon Health in Victoria told The Washington Post.