A suspected hantavirus outbreak aboard a cruise ship has claimed three lives and left seven others ill.
There are five confirmed cases of the virus and several people who were on board the MV Hondius are isolating, including a two who returned to the UK and a British man in hospital in the Netherlands.
The World Health Organization (WHO) said that detailed investigations are currently underway into the incident, including extensive laboratory testing and epidemiological studies to understand the virus's spread. Sequencing of the virus from the current outbreak is also ongoing.
Hantaviruses, which have been present for centuries, have a documented history of outbreaks across Asia and Europe, but it is rare to pass between humans.
In the Eastern Hemisphere, these viruses have been associated with severe conditions such as haemorrhagic fever and kidney failure.
Follow latest updates on the cruise ship outbreak here
A distinct group of hantaviruses emerged in the early 1990s in the southwestern United States, leading to the acute respiratory disease now known as hantavirus pulmonary syndrome.
The disease garnered significant attention in 2025 following the death of Betsy Arakawa, wife of actor Gene Hackman, from a hantavirus infection in New Mexico.
What is hantavirus?
Hantavirus is mainly spread by contact with rodents or their urine, saliva or droppings, particularly when the material is disturbed and becomes airborne, posing a risk of inhalation.
People are typically exposed to hantavirus around their homes, cabins or sheds, especially when cleaning out enclosed spaces with little ventilation or going into areas where there are mouse droppings.
Hantavirus is such a “such a severe disease” there are global efforts to try and develop vaccines against it, Professor Robin May, chief scientific officer at the UK Health Security Agency (UKHSA) has said.
The virus is widespread around the world but it is rare to spread between humans.
“This one, in particular, the Andean strain, is the only one for which there is some evidence in the past of human to human transmission, and so that’s obviously our primary focus here,” he told BBC Breakfast.
The US Centers for Disease Control and Prevention began tracking the virus after a 1993 outbreak in the Four Corners region – the area where Arizona, Colorado, New Mexico and Utah meet.
It was a doctor with the Indian Health Service who first noticed a pattern of deaths among young patients, said Michelle Harkins, a pulmonologist with the University of New Mexico Health Sciences Center who for years has been studying the disease and helping patients.
Most US cases are in Western states. New Mexico and Arizona are hotspots, Dr Harkins said, likely because the odds are greater for mouse-human encounters in rural areas.
A couple’s bird watching trip while in Argentina may explain how the virus got onto the ship, officials investigating the outbreak said. The pair may have been exposed to infected rodents while birdwatching at a landfill site in Ushuaia.
Symptoms of hantavirus
An infection can rapidly progress and become life-threatening. Experts say it can start with symptoms that can include:
- fever
- chills
- muscle aches
- headache
“Early in the illness, you really may not be able to tell the difference between hantavirus and having the flu,” said Dr Sonja Bartolome of UT Southwestern Medical Center in Dallas.
Symptoms of hantavirus pulmonary syndrome usually show between one to eight weeks after contact with an infected rodent. As the infection progresses, patients might experience tightness in the chest, as the lungs fill with fluid.
The other syndrome caused by hantavirus — hemorrhagic fever with renal syndrome — usually develops within a week or two after exposure.
Death rates vary depending on which hantavirus causes the illness. Hantavirus pulmonary syndrome is fatal in nearly 40 per cent of people infected, while the death rate for hemorrhagic fever with renal syndrome varies from 1 per cent to 15 per cent of patients, according to the CDC.
How to prevent hantavirus
There is no specific treatment or cure, but early medical attention can increase the chance of survival.
Despite years of research, Dr Harkins said that many questions have yet to be answered, including why it can be mild for some people and very severe for others and how antibodies are developed. She and other researchers have been following patients over long periods of time in hopes of finding a treatment.
“A lot of mysteries,” she said, noting that what researchers do know is that rodent exposure is a key.
The best way to avoid the germ is to minimise contact with rodents and their droppings. Use protective gloves and a bleach solution for cleaning up rodent droppings.
Public health experts caution against sweeping or vacuuming, which can cause the virus to get into the air.
How many people are isolating?
Health chiefs have been tracing individuals on the boat and contacts they made on shore in South America.
There are currently several passengers and staff from the MV Hondius who are isolating.
British hantavirus patient Martin Anstee, 56, was an expedition guide on board, and is currently isolating in hospital in the Netherlands.
Two people who were on board the ship and returned to the UK are self isolating, but are not showing any symptoms, according to UKHSA. Another Briton is in hospital in South Africa.
The UKHSA said people may need to be isolated for up to eight weeks, but reassured the risk to the public “remains very low.”
Prof May said: “So with all transmissible diseases, we undertake contact tracing after the first case is identified. And this one, of course, has been a very intense effort, and I’m very grateful for both people within the organisation and all those members of the public who’ve helped us with this.
“So it’s been quite a mammoth effort. We will continue to do that if other information arises.”
He explained family members, people who might have shared a room on the cruise, sat directly next to somebody on a long haul flight, will be contacted.
He added: “We’re not including people who may be very transient contacts – such as who you might have walked past in the airport – because the risk of transmission there is extremely low.”
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