What Is Hantavirus? The Rare Virus Linked to Cruise Ship Deaths

When a cluster of severe respiratory illness swept through the Dutch‑flagged cruise ship MV Hondius in April 2026, investigators quickly identified a rare culprit: hantavirus. Seven passengers developed fever, pulmonary symptoms and gastrointestinal complaints, two of whom were later laboratory‑confirmed to be infected and three of whom died.

The ship had sailed from Ushuaia, Argentina, and experts say passengers may have been exposed to the virus during shore excursions in South America, where Andes virus is endemic. Dr Charlotte Hammer of the University of Cambridge noted that although the ship’s passengers and crew face a higher risk due to shared exposures, the risk to the general public remains “very small”.

Dr Benjamin Brennan of the University of Glasgow emphasised that the World Health Organization (WHO) still needs to determine whether the infection was acquired in port or on board and whether limited person‑to‑person transmission occurred.

Hantaviruses are zoonotic RNA viruses belonging to the order Bunyavirales. They co‑evolved with specific rodent hosts and are divided into Old World hantaviruses found in Europe and Asia and New World hantaviruses found in the Americas.

Prof Sir Andrew Pollard of the University of Oxford explains that the New World viruses typically cause a life‑threatening respiratory illness called hantavirus pulmonary syndrome, whereas Old World viruses tend to cause haemorrhagic fever with renal syndrome. Because different hantavirus species are tied to particular rodent hosts, most human cases involve exposure to rodent urine, faeces or saliva rather than direct contact with other people.

Transmission occurs when people inhale aerosols generated from contaminated rodent excreta or, less commonly, through bites. Dr Giulia Gallo of the Pirbright Institute notes that household cleaning of rodent‑infested areas or touristic activities in endemic regions may create such exposures.

Human‑to‑human transmission is extremely rare; experts stress that only the Andes strain has been documented to spread between people under conditions of close and prolonged contact. Once infected, patients often experience non‑specific, flu‑like symptoms including fever, muscle aches and headache before rapidly progressing to respiratory distress and shock in severe cases.

New World hantavirus infections carry a case‑fatality rate of 30–40 percent, and there are no approved vaccines or specific antiviral treatments; care is supportive and usually requires intensive monitoring.

Despite the alarming cluster on the MV Hondius, experts urge perspective. Dr Hammer reiterates that outbreaks usually arise from a single environmental exposure and that “human‑to‑human transmission is rare”. Prof Mark Fielder of Kingston University emphasises that strict infection‑control measures isolating infected patients, monitoring close contacts and enforcing hand hygiene can limit onward spread.

The WHO reports that hantavirus infections remain uncommon globally and that, even in the Americas, only 229 cases were recorded in 2025 with a case‑fatality ratio of about 25 percent.

By early May 2026, WHO and national authorities assessed the public‑health risk as low and focused on contact tracing, testing and quarantine to protect passengers and crew. For travellers, avoiding contact with rodents and their excreta and seeking prompt medical care if symptoms appear are the main safeguards.