The suspected hantavirus outbreak on the MV Hondius cruise ship , which has killed three people and sickened at least three others, has two likely causes — and both are bad news for the 150 passengers on board, experts said. The most likely scenario is that passengers on board contracted the virus from the feces, urine or saliva of infected rats or mice. That’s the usual transmission vector, according to physician Zaid Fadul, a former Air Force flight surgeon.  But there’s one strain of the