A hantavirus cluster on a cruise ship is spreading person to person, a first
Five confirmed cases and three deaths, all linked to Andes virus, the only hantavirus known to pass between people. WHO calls the public health risk low but says more cases are possible.
The World Health Organization is coordinating a multi-country response to a cluster of hantavirus cases aboard the cruise ship MV Hondius, after laboratory testing confirmed the pathogen as Andes virus — the only hantavirus species known to be capable of limited transmission between people [s1].
Briefing media on 7 May, Director-General Tedros Adhanom Ghebreyesus said eight cases had been reported at that point, including three deaths, with five of the eight confirmed as hantavirus infections [s1]. "While this is a serious incident, WHO assesses the public health risk as low," he said, while cautioning that "given the incubation period, it's possible that more cases may be reported" [s1].
How the cluster surfaced
WHO says it was first notified of the situation on Saturday, 2 May [s1]. A Disease Outbreak News item published two days later, on 4 May, described a cluster of passengers with severe respiratory illness aboard the ship, which was carrying 147 passengers and crew; at that point seven cases had been identified — two laboratory-confirmed and five suspected [s2]. By the time of the 7 May briefing, the confirmed count had risen to five and the death toll to three [s1].
Why Andes virus is unusual
Most hantaviruses infect people through contact with rodent urine, droppings or saliva, typically via inhaled dust in enclosed spaces — not from other infected people. Andes virus is the exception: WHO's briefing specifically flagged it as "the only species known to be capable of limited transmission between humans," tied to close and prolonged contact [s1]. That distinction is what elevates a cluster of cases traveling together on a single vessel from a shared-exposure event to a scenario health authorities have to actively rule human-to-human spread in or out of.
The response so far
Since being notified on 2 May, WHO says it has deployed an expert onboard the ship to support a comprehensive medical assessment of all passengers and crew and to gather information for evaluating their individual infection risk [s1]. The organization has also arranged shipment of 2,500 diagnostic kits from Argentina — where Andes virus is endemic and diagnostic capacity is well established — to laboratories in five countries, to expand testing capacity beyond the ship's port of call [s1]. WHO says it is also developing step-by-step operational guidance for the safe and respectful disembarkation and onward travel of passengers and crew [s1].
Dr. Tedros described WHO's priorities as ensuring affected patients receive care, that remaining passengers are kept safe and "treated with dignity," and preventing further spread of the virus [s1]. He also framed the episode as a case study for the instruments WHO relies on to manage exactly this kind of event: "This event demonstrates why the IHR exist," he said, referring to the International Health Regulations that define the rights and obligations of countries and WHO in responding to public health events that cross borders, "demonstrating the importance of global cooperation and solidarity in responding to health threats that know no borders" [s1]. WHO says it is coordinating closely with multiple countries under those regulations [s1].
What is not yet known
Neither WHO statement identifies the ship's itinerary, the nationalities of the affected passengers, or where exposure is believed to have occurred — whether from a shared source (such as rodent-contaminated areas the ship visited) or through onward transmission between passengers once symptoms began. Andes virus is endemic to parts of South America, and a shared-source exposure during a port call would carry different implications for other passengers and crew than a chain of person-to-person transmission would.
WHO's own framing — a low global risk assessment paired with an explicit warning that more cases are likely given the incubation period — reflects that uncertainty. Hantavirus infections can take one to five weeks to produce symptoms after exposure, which means the current case count may not represent the full extent of exposure aboard the ship.
What to watch
Whether additional cases emerge among passengers or crew as the incubation window plays out, and whether any of those cases show evidence of transmission chains distinct from the original exposure — the detail that would confirm or rule out sustained human-to-human spread. Also worth watching: whether the diagnostic kits WHO shipped to five countries turn up cases among passengers who have already dispersed to their home countries, which would test how well the disembarkation guidance WHO is developing actually functions in practice.
Sources
- [s1] World Health Organization, "WHO's response to hantavirus cases linked to a cruise ship," 7 May
- [s2] World Health Organization, "Hantavirus cluster linked to cruise ship travel, Multi-country," Disease Outbreak News, 4 May 2026. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON599
Sources
- WHO's response to hantavirus cases linked to a cruise ship — World Health Organization , May 7, 2026
- Hantavirus cluster linked to cruise ship travel, Multi-country (Disease Outbreak News) — World Health Organization , May 4, 2026
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