WHO probes possible human spread of hantavirus on cruise

A polar expedition cruise ship stranded off Cape Verde with around 150 people on board has become the focus of a World Health Organization investigation into a deadly hantavirus outbreak, with publicly available information indicating that rare human-to-human transmission among passengers may have occurred.

Deadly outbreak unfolds on polar expedition voyage

The Dutch-flagged MV Hondius set sail from Argentina on April 1 for a weeks-long expedition cruise that included remote South Atlantic islands. According to published coverage and World Health Organization updates, a cluster of severe respiratory illnesses began emerging among passengers in early April, eventually leading to three deaths and several additional suspected infections.

The first known patient, a Dutch passenger in his seventies, developed fever, headache and mild gastrointestinal symptoms around April 6 while the ship was at sea. His condition deteriorated over the following days, and he died on April 11. A second passenger, believed to be his spouse and travel companion, also became ill after leaving the vessel and later died in a hospital in South Africa on April 26. Laboratory testing there confirmed infection with hantavirus.

By early May, the World Health Organization had been notified of seven confirmed or suspected cases linked to the voyage, including three fatalities, one patient in critical condition in intensive care, and several people with milder illness. The cases include passengers who disembarked and fell ill later, prompting health agencies in multiple countries to begin tracing close contacts on board and on subsequent flights.

As the scale of the outbreak became clear, Cape Verde refused to allow passengers and crew to disembark, leaving the ship anchored off the capital, Praia. Reports indicate that around 147 passengers and crew remain confined to the vessel while international arrangements are made for medical evacuations and a safe port of disembarkation.

WHO examines possible human-to-human transmission

Hantaviruses are typically spread to people through exposure to the droppings, urine or saliva of infected rodents. For most known strains, person-to-person spread is not considered a significant route of transmission. However, the Andes virus, found in parts of South America, has previously been associated with limited human-to-human spread among close contacts.

In its disease outbreak update on the cruise cluster, WHO noted that two of the earliest patients had recently traveled extensively in South America, including Argentina, before embarking. Based on this travel history and known risk areas, publicly available information suggests that they may have been exposed to the virus on land rather than on the ship itself.

What has drawn particular concern is the pattern of illness among other passengers. A small number of additional cases with severe respiratory disease and compatible laboratory findings do not appear to share the same clear environmental exposure to rodents. Timelines compiled from WHO technical briefings and news reports show that symptom onset for these passengers occurred between April 6 and April 28, in some instances after prolonged time together on board.

On May 5, WHO technical experts speaking at a press briefing said their working assumption was that some degree of human-to-human spread may have taken place among very close contacts, such as people sharing cabins or spouses. They emphasized that any such transmission appears to be rare and limited in scope, given the relatively small number of cases on a vessel where passengers and crew have lived in close quarters for weeks.

Ship stranded as evacuation and port plans shift

The outbreak has left the MV Hondius caught in a geopolitical and logistical bind. Authorities in Cape Verde initially declined requests to evacuate some of the sickest individuals locally, citing limited capacity to manage complex intensive care cases. As a result, medical evacuations have had to be organized over long distances, involving multiple countries.

In recent days, publicly available information shows that several patients, including the ship’s doctor, have been airlifted from Cape Verde to the Netherlands for advanced treatment. Another critically ill passenger, a British national, was previously evacuated to a hospital in South Africa, where intensive care specialists are managing severe respiratory failure consistent with hantavirus pulmonary syndrome.

Meanwhile, the ship has been searching for a safe harbor where remaining passengers and crew can disembark. Initial plans for the vessel to dock in Spain’s Canary Islands reportedly encountered setbacks as regional authorities weighed public concern and hospital capacity. News coverage on Wednesday indicated that Spain has now signaled readiness in principle to receive the ship in the Canaries under strict health protocols, though the timeline for arrival and disembarkation remains closely managed.

For those still on board, the prolonged period at anchor has created mounting anxiety. Accounts reported by international media describe older passengers in particular facing not only the fear of infection but also delays in care for unrelated medical conditions that would ordinarily be handled quickly ashore.

What this means for travelers and the cruise industry

The Hondius outbreak represents what researchers describe as the first documented cluster of hantavirus infections on a cruise ship. For an industry still recovering from the reputational shock of COVID-19, images of another vessel held offshore because of a respiratory virus are an unwelcome reminder of how quickly health events at sea can gain global attention.

Hantavirus infections remain rare worldwide, and public health agencies have stressed in open statements that the risk to the general traveling public is very low. The pattern on the Hondius, with a small cluster of cases despite weeks of close contact, appears consistent with earlier observations that even Andes virus, the strain most associated with person-to-person spread, does not transmit as easily as many respiratory viruses.

Nonetheless, the incident is likely to prompt fresh scrutiny of how cruise lines assess and manage less familiar infectious threats. Investigators are examining whether any environmental contamination involving rodents could have occurred on board or during land excursions, even if the initial exposure happened on shore. Operators may face new pressure to demonstrate robust pest-control measures, medical staffing and isolation facilities on smaller expedition vessels as well as on large ocean liners.

Travel medicine specialists cited in news coverage are also highlighting the importance of pre-trip advice for travelers heading to areas where hantaviruses circulate in wild rodent populations. That guidance generally includes avoiding contact with rodent nests and droppings, ensuring good ventilation in rural accommodations and seeking prompt medical care if fever and respiratory symptoms develop after travel in affected regions.

Global health response and next investigative steps

As of early May, the World Health Organization and national public health agencies are continuing to piece together a detailed picture of how and where the virus spread among Hondius passengers. Teams are mapping cabin locations, shared activities and excursion histories to better understand potential chains of transmission, both from rodents to humans and, potentially, between people.

Laboratories are conducting genetic analysis of virus samples from confirmed cases to determine the exact strain involved and compare it with sequences from recent outbreaks on the South American mainland. If the virus is confirmed to be an Andes-lineage hantavirus, genetic data could help clarify whether secondary cases on the ship are more consistent with a common environmental exposure or with limited human-to-human spread.

At the same time, health authorities in countries visited by the ship or connected through passengers’ onward travel are carrying out contact tracing and issuing guidance to clinicians. Hospitals in South Africa and Europe have been alerted to consider hantavirus infection in patients presenting with sudden respiratory failure and a recent history of travel on the Hondius or to specific South American regions.

For now, the outbreak remains contained to a very small number of individuals. Investigators say that understanding precisely what happened on the Hondius will help refine global guidance on hantavirus surveillance, infection prevention on ships and the management of future clusters in both travel and community settings.