An outbreak of the rare hantavirus unfolded over weeks on a cruise ship as it sailed across the Atlantic Ocean . At least three passengers have died and several others are sick and were evacuated from the ship. Health authorities are trying to trace passengers who left the ship previously and people who might have had contact with them. More than 140 passengers and crew members are still aboard the Dutch-flagged MV Hondius as it heads for Spain's Canary Islands. Hantavirus is a rodent-borne infection that in rare cases can be transmitted from person to person, though the World Health Organization says the risk to the wider public is low because the virus can’t easily be passed between people. Here's a timeline of the outbreak: April 1 The ship sets off from Ushuaia in the far south of Argentina. Scheduled stops include Antarctica and several isolated South Atlantic Ocean islands. April 6 A 70-year-old Dutch man becomes sick on board with fever, headache and mild diarrhea.…