Nearly 40 passengers exposed to a deadly hantavirus outbreak are believed to have walked off a cruise ship without contact tracing and scattered across multiple countries, leaving authorities scrambling to find them.

Oceanwide Expeditions, the company that operates the Dutch-flagged MV Hondius, said Thursday that 29 passengers disembarked on April 24, nearly two weeks after the first death on board, while Dutch officials put the number closer to 40.

The passengers, representing at least a dozen nationalities, returned to their home countries across Europe, Africa and beyond, creating a complex international search effort, the company said, adding that nationalities of two of the people were unknown.

Health officials have already confirmed that at least one passenger who left the ship, a man who returned to Switzerland, tested positive for the Andes strain of the hantavirus, a rare variant that can spread between people through close contact.

CRUISE SHIP PASSENGER DESCRIBES UNCERTAINTY AFTER 3 DEATHS AMID HANTAVIRUS PROBE

The outbreak has already resulted in at least three deaths, while several others have fallen ill as the virus spread among passengers.

A Dutch man died on April 11, and his body was taken off the ship onto the remote South Atlantic island of St. Helena. His wife also disembarked there before flying to South Africa, where she collapsed and died at the Johannesburg airport.

Argentine officials told The Associated Press on Wednesday that the leading hypothesis is that the couple may have been exposed to rodents while visiting a landfill during a bird-watching tour in the city of Ushuaia, unknowingly contracting the virus before boarding the cruise ship.

RARE HANTAVIRUS HUMAN-TO-HUMAN TRANSMISSION SUSPECTED ON LUXURY CRUISE SHIP WHERE 3 HAVE DIED

Hantavirus usually spreads by inhaling contaminated rodent droppings. The World Health Organization (WHO) said human-to-human transfer is uncommon, but possible.

Additional evacuations followed the Dutch man’s death.

A British man was flown to South Africa from Ascension Island, according to the company, while three more people, including the ship’s doctor, were airlifted to Europe for treatment as the vessel drifted near Cape Verde.

With passengers dispersing across continents and limited records of their movements, officials in South Africa and across Europe are now working to reconstruct travel paths and identify anyone who may have been exposed.

The Associated Press contributed to this report.