A dream trip has turned into a floating nightmare for passengers and crew aboard the MV Hondius , where a hantavirus outbreak has killed three and sickened at least four others . Nearly 150 people still on board are in quarantine after health officials confirmed that two passengers were infected with the Andes strain, a rare and dangerous version of the virus that can spread from person to person. But Dr. Jill Roberts , a molecular epidemiology expert with the University of South Florida College of Public Health in Tampa, told The Post that there’s another virus she considers an even greater threat if it ever reached a cruise ship. The MV Hondius is stranded at sea amid fears of potential spread of the rare hantavirus amid an outbreak on board. AFP via Getty Images “The one that keeps me up at night is measles,” she said.…