Three people have died and others have been sickened by what health authorities suspect is a hantavirus outbreak on a cruise ship in the Atlantic Ocean. Hantaviruses exist throughout the world and are spread by contact with rodents. It's rare but also possible for a hantavirus to spread between people. In severe cases, the virus can cause a deadly lung infection or hemorrhagic fever with kidney failure. There is no specific treatment or cure for hantavirus infections, but early medical attention can increase the chance of survival.