WHO center confirms human-to-human hantavirus spread on cruise ship, killing 3 of 13

In April 2026, 13 passengers aboard the cruise ship M/V Hondius developed severe respiratory illness consistent with hantavirus pulmonary syndrome, and three died. The ship had departed Ushuaia, Argentina, on April 1. The WHO Collaborating Center at the University of Geneva and Geneva University Hospitals analyzed samples and identified the Andes virus, a strain known to circulate in southern South America.

Researchers published findings in Science after combining contact tracing with viral genome sequencing. The first case appeared on April 3, soon after departure, but a later case developed symptoms May 31, 60 days after leaving Argentina, beyond the usual maximum incubation period for rodent-to-human infection, about six weeks. That patient had close, prolonged contact with another confirmed case. Sequencing in 10 of 13 patients showed highly similar viral genomes. The evidence is observational, relying on timing, contact patterns and sequence similarity.

Most hantaviruses spread to people through dust contaminated by rodent secretions, not through casual person-to-person contact. The Andes virus is an exception, with documented spread only after close, prolonged contact. The findings did not establish casual transmission. The outbreak strain was genetically close to natural Andes virus lineages circulating in Argentine Patagonia, according to a second Science paper. That finding counters rumors of an engineered, reassorted or unusually mutated virus. Independent comparisons across laboratories in France, Switzerland, the Netherlands, Spain, Canada, Senegal and South Africa strengthened the genomic conclusions.

The result matters because cruise ships concentrate people from many countries in shared indoor spaces for days, a setting where close, prolonged contact can occur. Confirming human-to-human transmission of the Andes virus in this environment gives public health teams a clearer reason to trace contacts, isolate cases and test close exposures after a rodent-linked introduction. It also shows how quickly a localized Patagonian virus lineage can be linked to an international outbreak through coordinated laboratory work.