How a rare Hantavirus outbreak on a cruise ship triggered a global health probe

A deadly hantavirus outbreak aboard the Dutch expedition cruise ship MV Hondius has triggered an international health investigation after multiple passengers developed severe respiratory illness linked to the rare Andes strain of the virus.

At the centre of the investigation are Dutch passengers Jan de Vries and his wife, Maria de Vries, whose illness is now believed to be among the earliest known cases connected to the outbreak. Health authorities across Argentina, Europe, and South Africa are now trying to determine whether the virus was brought on board by an infected passenger or whether limited human transmission occurred during the voyage.

How the cruise outbreak unfolded

According to media reports, the MV Hondius departed from Ushuaia, Argentina, on April 1 for an expedition voyage through the South Atlantic. During the journey, several passengers and crew members began developing symptoms of serious respiratory illness.

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Jan de Vries became critically ill during the voyage and died on board on April 11. When the vessel later stopped at Saint Helena, his body was removed from the ship. His wife, Maria de Vries, who had also fallen ill, was taken off the vessel at the same stop and later medically evacuated to Johannesburg, South Africa, where she died.

A German passenger also died during the outbreak, while several other passengers and crew members required evacuation and medical monitoring.

Argentine health officials believe Jan and Maria de Vries may represent the first known infections linked to the outbreak, reported NDTV.

Why probe is focusing on the couple’s travels

According to Argentina’s Ministry of Health, the couple arrived in South America in November and spent several months travelling across Argentina, Chile, and Uruguay before returning to Argentina in late March. They boarded the MV Hondius in Ushuaia on April 1.

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Since symptoms appeared soon after embarkation, investigators suspect the virus may have been contracted before the cruise began. In a bid to trace where exposure to infected rodents may have occurred, authorities are now reconstructing the couple’s travel history, reviewing rural stays, trekking routes, wildlife excursions, and accommodation.

Hantavirus is a rodent-borne virus that usually infects humans after exposure to rodent urine, saliva, or droppings, often in rural or enclosed environments. In severe cases, it can cause hantavirus pulmonary syndrome, a life-threatening respiratory illness.

What makes the Andes Strain different

Laboratory testing identified the Andes strain of hantavirus in at least two patients linked to the MV Hondius. This strain, found mainly in Argentina and Chile, is the only hantavirus known to occasionally spread between humans through prolonged close contact. That has made the outbreak especially important for epidemiologists.

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The key question here is, could the virus have spread on board. Cruise ships create close-contact environments, with passengers sharing cabins, dining spaces, corridors, and enclosed common areas for extended periods. Those conditions can complicate outbreak investigations.

However, investigators working with the World Health Organisation told AFP that the earliest infections "could not have originated on the cruise itself," suggesting at least one passenger likely boarded while already infected.

What health authorities are trying to confirm now

Argentina has launched an extensive epidemiological investigation. Health teams are retracing Jan and Maria de Vries’ movements across South America while field experts are being sent to areas connected to their itinerary to capture and test rodents. Scientists are also conducting genomic sequencing and contact tracing to determine exactly where exposure occurred.

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According to media reports, investigators say one detail has complicated the case. The Andes strain has not been detected in Tierra del Fuego, where Ushuaia is located, since 1996. That strengthens the theory that the couple may have been infected earlier during their travels rather than immediately before boarding.

Public health authorities say the overall risk to the wider public remains low. Still, the MV Hondius outbreak has drawn global attention because Andes hantavirus remains one of the few zoonotic viruses capable of limited human transmission.

For investigators, the movements of Jan and Maria de Vries may hold the key to understanding how the outbreak began and whether the virus spread beyond its original source.