Three passengers died. Seven people are sick. The ship is anchored off the coast of Cape Verde, with passengers unable to disembark and the World Health Organization coordinating the response.
The suspected cause is hantavirus, a rodent-borne pathogen for which there is no treatment or approved vaccine. It’s not the disease we associate with cruise ships. The MV Hondius departed from Ushuaia, Argentina, on April 1st and passed through Antarctica and the island of St. Helena, now the site of what infectious disease experts are calling a truly unprecedented outbreak in this type of situation. Notably, authorities in Argentina’s Tierra del Fuego province, where the ship departed, confirmed that no hantavirus cases had been recorded in the province. However, the WHO notes that the virus is also endemic in other parts of Argentina and Chile.
Within hours of confirming the suspected diagnosis, WHO launched a coordinated international response under the International Health Regulations (IHR), including epidemiological investigation, laboratory testing, logistics, clinical management, and medical evacuation of symptomatic passengers, all in parallel. That means the system is working as designed. Pathogens move faster than national borders to unexpected places, requiring rapid and simultaneous action across multiple countries and jurisdictions before the full picture becomes clear.
The United States, which withdrew from the WHO in January 2025, received no notification.
Isolation from global health governance will become even more important in six weeks when the 2026 FIFA World Cup opens in 11 American cities.
What you need to know about hantavirus, a disease suspected of outbreak on a cruise ship
The MV Hondius outbreak has investigators now asking the question, “Why did this happen?”
Two possibilities are being considered. The first is rodent contamination on board the aircraft, when passengers inhale aerosolized virus from infected faeces. The second is more serious. It is an infection with Andes virus. Andes virus is endemic in the region of South America where this voyage began, and is one of the strains of hantavirus for which human-to-human transmission has been recorded.
All other known hantaviruses are not transmissible between humans. If Andean virus transmission is confirmed in a closed, high-density setting, it will change the way we think about the risk of outbreaks in contained settings. Hantavirus cardiopulmonary syndrome has a mortality rate of up to 50%. The incubation period can be 2 to 3 weeks, and in some cases up to 6 weeks. By the time someone shows symptoms, they may be far away from where they were infected.
The ship is carrying 147 passengers and crew representing 23 nationalities, according to the WHO. As of Monday, seven cases (two confirmed and five probable) were reported, including three deaths. The first patient, a 70-year-old man, developed fever, headache, and gastrointestinal symptoms on April 6 while en route from Ushuaia to St. Helena, and died on April 11 without microbiological tests. His 69-year-old spouse’s condition deteriorated on a flight to Johannesburg and she died after being rushed to the hospital on April 26. Later, a PCR test confirmed that she was positive for hantavirus. The third patient, a British national, developed fever, shortness of breath and pneumonia on April 24 and was evacuated to South Africa three days later. He was tested positive for the infection and remains in intensive care. The fourth patient, an adult woman, died on Saturday after symptoms of fever and fatigue that started just four days earlier rapidly worsened. Three more people with fever and gastrointestinal symptoms are still being evaluated. The epidemiology is still unclear.
This is exactly the kind of signal that requires real-time information sharing across borders. It was created to be administered by the WHO.
I would like to know exactly what the United States lost by withdrawing from the WHO, as it is often explained in abstract terms.
WHO’s value during the outbreak is operational. The Global Outbreak Alert and Response Network (GOARN), IHR notification cascades, rapid risk assessments, and pathogen sequence data shared in real time across a network of member states: these are not diplomatic expediencies. These are tools that compress the timeline from detecting a signal to responding to it. Time is of the essence in outbreak medicine. The gap between WHO notifications arriving in health ministries’ inboxes and the same information published in public press releases can be the difference between containment and spread.
The United States helped build that system. We funded it, shaped its architecture, and relied on it for decades. Then we moved away from that, and now we’re dealing with public information on the same timeline as everyone else connected to the internet.
US completes withdrawal from WHO
During most of the year, the gap is diffuse and difficult to ascertain. That won’t be the case this summer.
The 2026 FIFA World Cup is one of the most complex large-scale events ever held on American soil. The State Department announced in December that it expected 5 million to 7 million international visitors to travel through host cities over a six-week period at the height of summer. Even if these numbers are overestimates, huge numbers of people from more than 200 countries will arrive, bringing with them the entire geography of the world’s infectious diseases. Some people may have a disease that they don’t even know they have. Some people may seek treatment in emergency departments in the United States. Some people fly home before they develop symptoms.
Large gatherings increase in size. These concentrate people, accelerate transmission, and create conditions for local signals to become international events within a single latency period. Clinicians and health departments working on this tournament need to know what pathogens are circulating in the countries sending the largest delegations, which travelers are arriving from endemic areas, and what symptoms at the emergency department in July would cause concern rather than a routine discharge.
Those answers flow through WHO. We are no longer at the table where they are generated and shared.
MV Hondius is resolved. Viral sequencing will ultimately reveal whether the Andes virus traveled between people in closed spaces, and what that means for how we assess risk in environments such as stadiums and transportation hubs in the future. As always, public health will learn from this.
But the lesson for now, before a single World Cup game, is this: In infectious diseases, information is the intervention. The earlier a signal is detected, characterized, and shared, the more options there are for responding. We’ve built the infrastructure to make that possible. Then I was left with a system to run it.
This summer, 11 American cities will find out what that decision will cost.
Krutika Kupari is an infectious disease doctor in Dallas. Her research focuses on emerging infectious diseases, outbreak response, vaccine policy, and clinical care of complex infectious diseases. She has extensive experience in COVID-19, mpox, and Ebola through collaboration with numerous global partners, including the World Health Organization.
