Fears are growing over a potential international health scare after dozens of passengers left an expedition cruise ship without knowing they may have been exposed to hantavirus — a rare but potentially fatal disease spread by rodents.

Authorities are particularly concerned about 29 travelers who departed the MV Hondius on April 24 at the remote island of St Helena, just under two weeks after the first reported death onboard. Those passengers later traveled home to several countries, including the UK, the US, and Australia.

Unlike the remaining guests and crew still aboard the vessel — who are reportedly following strict isolation and sanitation measures — the passengers who disembarked earlier resumed everyday activities before learning they could have been exposed to the virus.

One Spanish traveler still on board told local media that passengers dispersed rapidly across multiple continents after leaving the ship.

“The Australian returned home to Australia, the American passengers flew back to different parts of North America, and others headed to England and the Netherlands,” the passenger reportedly said.

British health officials have confirmed that seven UK nationals were among those who left the cruise early. At least two of them are now self-isolating as a precaution after concerns over possible exposure.

Meanwhile, US passengers who had boarded the expedition in Ushuaia, Argentina, are now reportedly under observation in states including California, Georgia, and Arizona.

The outbreak onboard the luxury expedition vessel has already claimed three lives and triggered an international investigation into how the infection began.

According to Argentine authorities, investigators believe the virus may have originated during a birdwatching excursion near a landfill site in Ushuaia, often nicknamed “the end of the world” because of its location at the southern tip of Argentina.

Their leading theory suggests that a Dutch couple who later died may have contracted the disease while visiting a rubbish dump heavily populated by seabirds and rodents shortly before the ship departed.

Hantavirus infections are rare but can become extremely serious, with some strains carrying mortality rates of up to 40 percent. The illness is commonly associated with exposure to rodent droppings, urine, or saliva.

Health agencies are continuing to monitor former passengers and trace potential contacts as concerns grow that the outbreak may already have spread far beyond the isolated cruise route where it first emerged.