By Bunmi Yekini
Three passengers are dead and a cruise ship carrying 149 people from 23 countries is stranded off the coast of West Africa after a suspected outbreak of hantavirus, one of the world’s rarest and most lethal viral infections, turned a holiday voyage into a medical emergency at sea.
The World Health Organisation confirmed the deaths on Sunday after the outbreak was detected aboard the MV Hondius, a Dutch-operated expedition vessel now anchored off Praia, the capital of Cape Verde, an island nation off the west coast of Africa.
The three dead are cruise passengers. The person currently in intensive care in a South African hospital is the only laboratory-confirmed hantavirus case linked to the ship so far. There are five more suspected cases under investigation.
Cape Verde’s Health Minister has refused to allow anyone to disembark. WHO says it is working to evacuate two symptomatic passengers for urgent medical treatment.
Hantavirus is a family of viruses carried by rodents, primarily rats and mice, and transmitted to humans mainly through contact with infected urine, droppings, or saliva. People are most commonly exposed in enclosed or poorly ventilated spaces where rodent activity is present. Activities such as farming, forestry work, and cleaning cabins or sheds significantly raise the risk of infection.
Early symptoms include fatigue, fever, and muscle aches, symptoms so non-specific that they can easily be mistaken for influenza or COVID-19. What follows, in severe cases, is far harder to mistake. In the Americas, the virus progresses to hantavirus pulmonary syndrome, a condition in which the lungs fill rapidly with fluid, leading to respiratory failure and, in many cases, death.
In the United States, hantavirus carries a fatality rate of approximately 50%. There is no vaccine. There is no antiviral cure. Patients receive only supportive care, oxygen therapy, mechanical ventilation, and in severe cases, dialysis, while their bodies fight the infection alone.
The first passenger to fall ill was a 70-year-old man. He died on the ship, and his body was transferred to Saint Helena, a British territory in the South Atlantic. His 69-year-old wife became ill next, was evacuated to South Africa, and died in a Johannesburg hospital. The patient currently in intensive care is reported to be a 69-year-old British national.
The MV Hondius left Ushuaia, Argentina, more than a month ago, a detail now central to the investigation. Argentina and Chile are among the most active hantavirus zones on earth. The Andes variant of the virus, found specifically in southern South America, is the only known hantavirus strain with documented evidence of spreading directly between people, primarily through close, prolonged contact between household members or intimate partners.
There are two plausible explanations for how the virus reached the ship, according to Dr. Scott Miscovich, a family physician and infectious disease specialist. Either the vessel became contaminated with rodent feces or urine during its time in Argentina, or one of the passengers boarded already infected with the Andes variant and transmitted it to fellow travellers.
The second possibility is what is keeping scientists awake.
“When I first read this, I thought that they were making a misprint,” Dr. Miscovich told CNN. If the evidence points to human-to-human transmission on board, he said, it will “change the future of travel medicine and infectious disease and tropical medicine.”
Hantavirus is not a new disease. It simply rarely makes headlines.
The virus takes its name from the Hantaan River in South Korea, where it was first formally isolated in 1978. Scientists later traced outbreaks in Russia as far back as 1913, and confirmed it caused the haemorrhagic fever that hospitalized thousands of soldiers during the Korean War in the 1950s.
Its most dramatic emergence in the modern era came in the spring of 1993, in the Four Corners region of the American Southwest, the point where New Mexico, Arizona, Colorado, and Utah converge. A 19-year-old Navajo man was travelling with his family to his fiancée’s funeral when he began struggling to breathe in the back seat of the car. His family pulled over to call an ambulance. He died before help could save him, his lungs flooded with fluid. The ER doctors who received him were struck by the eerie similarity to his fiancée’s death just weeks before.
Investigators quickly found more cases. By the end of 1993, 48 Americans had been confirmed infected and 27 were dead, a fatality rate of 56%. The outbreak was later traced to a tenfold increase in the deer mouse population, driven by unusually heavy spring rainfall from an El Niño winter that flooded the region with vegetation and food for rodents.
The virus identified from that outbreak was eventually named Sin Nombre, Spanish for “nameless”, after the Navajo community objected to the disease being associated with their homeland following a wave of racial discrimination triggered by early media coverage.
Once scientists were able to examine historical tissue samples, they discovered that the first known human victim of hantavirus pulmonary syndrome was actually a 38-year-old man in Utah who died in 1959, 34 years before the virus had a name.
Worldwide, between 10,000 and 100,000 hantavirus infections are estimated to occur every year, with the largest burden falling on Asia and Europe, particularly China and South Korea, where thousands of cases of haemorrhagic fever with renal syndrome, the kidney-attacking variant of the disease, are reported annually.
In the Americas, the picture is grimmer by fatality rate. Chile recorded 35 confirmed cases and seven deaths in 2025. Paraguay recorded 27 cases, above its four-year average, including an outbreak among road construction workers, with six deaths and a fatality rate of 22%. The United States reported confirmed infections across five states in the same year.
The virus also claimed a high-profile victim in 2025: Betsy Arakawa, concert pianist and wife of Hollywood actor Gene Hackman, died from hantavirus pulmonary syndrome at their home in Santa Fe, New Mexico. Hackman died approximately one week later from heart disease.
As of Monday morning, 149 people, 88 passengers and 61 crew, remain aboard the MV Hondius with no confirmed timeline for disembarkation. WHO says it is coordinating medical evacuations and sequencing the confirmed virus sample to determine exactly which hantavirus strain is involved. That result will answer the question the entire infectious disease community is now watching: was this rodent contamination, or did the virus travel from person to person in the middle of the Atlantic Ocean?
WHO’s regional director for Europe, Hans Kluge, said there is “no need for panic or travel restrictions,” and that the outbreak does not represent a public health threat.
But among those still on board, the language is less clinical. Travel blogger Jake Rosmarin posted an emotional video from the ship Monday morning. “What’s happening right now is very real for all of us here. We’re not just a story. We’re not just headlines. We’re people, people with families, with lives, with people waiting for us at home. There’s a lot of uncertainty, and that’s the hardest part,” he said.
Three of his fellow passengers boarded that ship in good health. They will not be going home.
The ship is still waiting. And so is science.