The last passengers have disembarked from the MV Hondius, a polar expedition cruise ship at the centre of a growing hantavirus outbreak, as authorities confirmed new cases across several countries and scientists published evidence that the virus spread between passengers on board. Three people have died, seven cases have been confirmed, and two more are suspected, according to the World Health Organization.

The MV Hondius — operated by Dutch company Oceanwide Expeditions — departed Ushuaia, at the southern tip of Argentina, on 1 April carrying 147 passengers and crew from 23 countries. The ship docked in Tenerife, in Spain's Canary Islands, where passengers have been evacuated over the past several days. Among the newly confirmed cases are an American, a French national, and a Spanish citizen quarantining in Madrid, while two British nationals are being treated in the Netherlands and South Africa. A French woman isolating in Paris is reported to be in deteriorating health, with 22 contacts traced. The US Department of Health and Human Services confirmed that two American passengers were repatriated on Sunday in biocontainment units and that all 17 US citizens on that flight are undergoing clinical assessment at a facility in Nebraska. Four Canadian passengers landed in British Columbia and are self-isolating, while Australia and New Zealand are repatriating their nationals to a quarantine facility near Perth, Western Australia.

A joint genomic study by laboratories in South Africa, Switzerland, and the Netherlands, published on the open scientific platform Virological, has confirmed that the strain responsible is the Andes variant of hantavirus, and that it spread from passenger to passenger during the voyage — the first internationally documented episode of person-to-person transmission of this strain aboard a means of transport. Researchers found the viral genomes of five infected passengers to be "practically identical," indicating a single chain of contagion following an initial rodent-to-human infection. The study also ruled out significant mutations: the sequenced strain shares roughly 98% genetic similarity with Argentine samples from 1997 and 2018, and the two mutations identified carry no functional consequences.

Andes virus is the only hantavirus known to spread between humans, a capacity established after a cluster in Argentine Patagonia in 2018–19 infected 34 people and killed 11. However, experts and the WHO stress that it does not have the characteristics needed to trigger a pandemic. Unlike SARS-CoV-2, which spreads efficiently through the air even before symptoms appear, Andes virus requires close, prolonged contact in crowded, poorly ventilated spaces — the conditions that existed on the MV Hondius. Fatality rates for American hantavirus strains, including Andes, can reach up to 50% in severe cases, but such infections remain rare globally. There is currently no licensed vaccine or specific antiviral treatment; care focuses on monitoring and managing complications.

The WHO recommends 42 days of quarantine for those exposed, reflecting the maximum incubation period. The US CDC's acting head, Dr Jay Bhattacharya, opted for a less restrictive approach, arguing that human-to-human transmission is rare and the situation should not be treated like Covid — a position the WHO said "may have risks." Countries are applying varying levels of precaution: Spain has placed some evacuees in mandatory quarantine at a military hospital, while the Netherlands has adopted a more flexible monitoring approach. Twenty-five crew members and two medical staff remain on board as the ship sails toward the Netherlands, where they will be quarantined on arrival.