Doctors have been warned to be on the lookout for "imported" hantavirus cases as American passengers return home from a cruise hit by an outbreak of the deadly disease. New Jersey joined five other states on Friday in announcing it was tracking residents who were onboard the MV Hondius, where eight cases of the illness were confirmed, with three deaths. Seven American passengers left the Dutch cruise ship last month, and 17 more are due to disembark in the Canary Islands on Sunday before being brought home.