New Delhi, May 13 -- More than 100 passengers aboard a luxury cruise ship hit by a hantavirus outbreak have now been evacuated, while health officials across several countries monitor passengers and close contacts for possible infections. Eighteen Americans have been placed in biocontainment units in Nebraska and Georgia.

So far, all 11 reported infections have been linked directly to passengers or crew aboard the MV Hondius, according to Tedros Adhanom Ghebreyesus, director-general of the World Health Organisation.

Hantaviruses usually spread through contaminated rodent droppings or urine. The Andes virus, identified on the cruise ship, is the only strain known to spread between people, though experts say it is unlikely to trigger a Co...