Three passengers have died, and seven others are ill aboard a ship anchored off Cape Verde, where passengers are currently unable to disembark. The World Health Organization (WHO) is overseeing the response to this situation.
The suspected cause of the outbreak is hantavirus, a pathogen carried by rodents that lacks both a cure and an approved vaccine. This virus is not typically linked to cruise ships. The MV Hondius, which embarked from Ushuaia, Argentina, on April 1, traversed Antarctica and St. Helena, and has become the focal point of what experts are calling an unprecedented outbreak in such a setting. Authorities in Tierra del Fuego, Argentina, from where the ship departed, have confirmed no prior cases of hantavirus there. However, WHO indicates that the virus is endemic in other parts of Argentina and Chile.
Upon confirming the suspected diagnosis, WHO swiftly launched an international response under the International Health Regulations (IHR). This response involves epidemiological investigations, laboratory testing, logistics support, clinical management, and medical evacuation of symptomatic passengers, all occurring concurrently. This illustrates the system functioning as intended: a pathogen crossing borders unexpectedly, necessitating rapid, coordinated actions across various countries and jurisdictions before the complete picture emerges.
The United States, having withdrawn from WHO in January 2025, did not receive any notification of this outbreak.
This separation from global health governance may have significant implications in six weeks when the FIFA World Cup 2026 takes place across 11 American cities.
The outbreak on the MV Hondius has prompted investigators to explore how this occurred.
Two potential causes are being considered. The first is contamination from rodents on the ship, leading to passengers inhaling the virus from infected excreta. The second, which could have broader implications, is infection with the Andes virus, a hantavirus strain known to spread between humans and endemic to the region of South America where the journey began.
Unlike other hantaviruses, the Andes virus can be transmitted from person to person. Confirming its transmission in a confined, densely populated setting would alter perceptions of outbreak risks in such environments. Hantavirus cardiopulmonary syndrome has a case fatality rate as high as 50%. The incubation period ranges from two to three weeks, sometimes extending to six. Therefore, individuals may be far from the exposure site when symptoms appear.
According to the WHO, there are 147 passengers and crew from 23 countries on the ship. As of Monday, there have been seven cases (two confirmed and five suspected), including three fatalities. The first patient, a 70-year-old man, developed a fever, headache, and gastrointestinal symptoms on April 6 while traveling from Ushuaia to St. Helena, and died on April 11 without microbiological testing. His 69-year-old spouse’s condition worsened during a flight to Johannesburg, where she died in the emergency department on April 26. A PCR test later confirmed her hantavirus infection. A third patient, a British national, developed a fever, breathing difficulties, and pneumonia on April 24 and was evacuated to South Africa three days later. He remains in intensive care with a confirmed infection. A fourth adult female died on Saturday after a rapid progression from fever and malaise over four days. Three more individuals with fever and gastrointestinal symptoms are under evaluation on the ship. The situation is still developing.
This incident underscores the need for real-time cross-border information sharing, a key focus of WHO’s mission.
It’s important to clarify what the United States lost by exiting WHO, often discussed in broad terms.
WHO’s operational value during outbreaks is significant. The Global Outbreak Alert and Response Network (GOARN), the IHR notification cascade, rapid risk assessments, and real-time sharing of pathogen sequencing data across member states are not mere diplomatic formalities. These are essential tools that shorten the time between detecting and responding to a threat. In outbreak medicine, every hour counts. The gap between receiving a WHO notification in a health ministry and that information becoming public can mean the difference between containment and spread.
The United States played a crucial role in establishing this system. We funded, shaped, and relied on it for many years. Now, having withdrawn, we access the same public information as anyone with internet access.
Throughout the year, this gap may go unnoticed, but it will be evident this summer.
The FIFA World Cup 2026 represents a highly complex mass gathering event on American soil. In December, the State Department anticipated 5 million to 7 million international visitors would pass through host cities over six weeks at the height of summer. Even if this estimate is high, millions will arrive from over 200 countries, bringing with them the world’s infectious disease landscape. Some may unknowingly carry illnesses. Some will seek care in American emergency departments, while others may return home before showing symptoms.
Mass gatherings intensify risks. They bring people together, accelerate transmission, and create conditions where a local issue can become an international event in one incubation period. Health professionals managing this tournament must know which pathogens are prevalent in countries with large delegations, which travelers are coming from outbreak zones, and which emergency presentations in July warrant concern rather than routine discharge.
These insights flow through WHO. The U.S. is no longer part of the discussions where they are generated and shared.
The MV Hondius situation will be resolved. Viral sequencing will eventually reveal whether the Andes virus transmitted between people in a confined space and what this implies for assessing risks in places like stadiums and transit hubs. Public health will gain insights from this, as it consistently does.
However, the immediate lesson, even before the World Cup begins, is this: In infectious disease management, information is critical. Early detection, characterization, and sharing of data provide more response options. We built the infrastructure to facilitate this, but we are no longer part of the system that operates it.
This summer, across 11 American cities, we will learn the consequences of this decision.
Krutika Kuppalli is an infectious diseases physician based in Dallas. Her expertise includes emerging infectious diseases, outbreak response, vaccine policy, and managing complex infections. She has worked with the World Health Organization.
