A rodent-borne illness is suspected of causing an outbreak aboard a cruise ship that has killed three people and sickened others. Studies indicate hantaviruses have been around for centuries, with outbreaks documented in Asia and Europe. In the Eastern Hemisphere, it has been linked with hemorrhagic fever and kidney failure. It wasn't until the early 1990s that a previously unknown group of hantaviruses emerged in the southwestern United States as the cause of an acute respiratory disease now known as hantavirus pulmonary syndrome.