Victims of a Hantavirus outbreak on a cruise ship may have got infected on a trip ashore, an expert in London has said.
Roger Hewson, a professor in Molecular Virology at the London School of Hygiene and Tropical Medicine, warned it was “important not to over interpret the cruise ship setting”.
Three people have died and at least three others are ill on the the Dutch-flagged cruise ship MV Hondius.
A British passenger and a British crew member were among those taken ill.
The ship is off the coast of Cape Verde, where it is hoped the medical evacuation of the British crew member along with a Dutch colleague, will take place, with Dutch authorities are leading evacuation plans. They are said to need “urgent medical care” after having acute respiratory symptoms.
Health leaders are investigating the source of the virus, with some experts suggesting that there could be a “mixture” of transmission, including close contact between passengers, such as sharing a cabin.
Professor Hewson has suggested the initial exposure, typically though contact with infected rodents’ faeces, saliva or urine, could have taken place offshore.
He said: “At this stage, based on the public information available, it’s important not to over interpret the cruise ship setting. The fact that cases have been identified in people associated with the same vessel does not by itself tell us whether exposure occurred on the ship, before boarding, during shore excursions, or through some other shared environmental exposure. That is precisely why public health investigations, laboratory confirmation and where possible, virus sequencing are important.”
The WHO also suspect the first person to fall ill could have contracted the virus before boarding the ship.
"We do believe that there may be some human-to-human transmission that is happening among the really close contacts," WHO official Dr Maria Van Kerkhove said.
Plans are being made for the “safe onward travel” of Britons stuck on the cruise ship, the Prime Minister has said.
Some 19 British nationals were listed as passengers on the ship, which was sailing from Argentina to Cape Verde, with four British crew members.
My thoughts are with those affected by the hantavirus outbreak onboard the MV Hondius.
— Keir Starmer (@Keir_Starmer) May 5, 2026
We are working closely with international partners to support British nationals on board and we’re putting plans in place for their safe onward travel.
The risk to the wider public remains…
Sir Keir Starmer said: “My thoughts are with those affected by the hantavirus outbreak onboard the MV Hondius.
“We are working closely with international partners to support British nationals on board and we’re putting plans in place for their safe onward travel.
“The risk to the wider public remains very low, protecting the British people is our number one priority.”
Passengers are confined to their cabins while “disinfection and other public health measures are carried out”, the World Health Organisation (WHO) said.
Tour operator Oceanwide Expeditions said the evacuation operation of the very sick is “complex” adding: “This will involve two specialised aircraft equipped with the necessary medical equipment and staffed by trained medical crews.
“This is not confirmed and is subject to change.”
Once the evacuations have taken place, it is understood the ship will move on to the Canary Islands.
Meanwhile the British passenger struck down by hantavirus is “understood to be improving”.
The passenger was medically evacuated on April 27 to Johannesburg and remains in intensive care.
A total of seven suspected cases have been identified – including three deaths.
Two of these cases have been confirmed as hantavirus.
Dr Maria Van Kerkhove, from the WHO, said: “As of today, seven individuals of the 147 passengers and crew have been reported ill, sadly, three have died.
“One patient is in intensive care in South Africa, although we understand that this patient is improving while two patients are still on board the ship and are being prepared for medical evacuation to the Netherlands for treatment.”
She added: “The plan is, and our highest priority is, to medically evacuate these two individuals to make sure that they have the care that they receive.”
Hantavirus latest: The UN World Health Organization (WHO) says human-to-human transmission aboard cruise ship in Atlantic Ocean cannot be ruled out, although it is rare. Seven of 147 passengers and crew have fallen ill and three have died. https://t.co/mY3ZwGQGsW pic.twitter.com/VhCVHzAvk6
— UN News (@UN_News_Centre) May 5, 2026
Dr Van Kerkhove said another suspected case has been reported but this person was “currently doing well and is asymptomatic”.
“At this stage, there are no additional symptomatic people on board, that said, the situation is being closely monitored and, as a precaution, passengers have been asked to remain in their cabins while disinfection and other public health measures are carried out,” she added.
Medical teams from Cape Verde are providing support to the ship but it will move to the Canary Islands where investigations and a full disinfection of the ship will take place, Dr Van Kerkhove said.
The WHO said that it “assesses the risk to the global population as low”.
A Dutch passenger died on board the ship on April 11.
On April 27, the wife of the passenger died, and authorities confirmed a variant of hantavirus
On May 2, a German passenger on board died, though the cause has not yet been confirmed.
“The atmosphere on board MV Hondius remains calm, with passengers generally composed,” Oceanwide Expeditions said in a statement.
“Oceanwide Expeditions is working to provide clarity and reassurance to guests and expedite their disembarkation and medical screening.”
Hantavirus infections, which are usually spread by infected rodents’ urine or faeces, can lead to severe respiratory illness and can sometimes be fatal.
While it is rare, hantavirus infections can spread between people, according to the WHO.
There is no specific treatment or cure, but patients have a better chance of survival if they receive medical attention early.
Dr Van Kerkhove told BBC Breakfast that the WHO’s “working hypothesis” is that the virus is being transmitted through a mixture of ways, including close contact.
“Our working hypothesis is that there’s probably a couple of different types of transmission that might be happening, maybe some exposure to rodents or their faeces or their saliva before passengers embarked, and potentially some limited human-to-human transmission among the contacts,” she said.
She added: “Our assumption is that it’s the Andes virus – hantaviruses are many different types of viruses.
“We do know that one of the viruses can transmit between people, but in previous outbreaks it’s been quite limited, and when I say limited I mean among close contacts or prolonged contact.
“We have a working hypothesis that there’s probably a mixture of different types of transmission.
“This is also a boat that went to many different islands – they were looking at wildlife, they were looking at birds, and on some of these islands there are rodents as well.
“So there could be a mixture of exposure to rodents in different places.
“But because some of the cases are close contacts, sharing cabins together, our assumption is that there’s a bit of a mix.”
Dr Charlotte Hammer, assistant professor and infectious disease epidemiologist at the University of Cambridge, said: “Outbreak investigations will be ongoing at the moment to establish the exposure of the cases.
“Hantavirus is present in Argentina and other parts of South America and has an incubation period of up to eight weeks.
“Therefore it is quite possible and even likely that the cases have been exposed during their time in South America.”
Mark Fielder, professor in medical microbiology at Kingston University London, added: “With the current understanding of the ongoing infection and the likelihood that stringent infection control measures are being implemented on board the vessel, it is likely that further ongoing transmission will be limited.
“The isolation of infected patients, regular handwashing, monitoring of close contacts, and the application of infection control measures will all be critical to limiting and halting onward spread of the disease.
“Once the ship docks it is likely that arrangements will be made for the remaining passengers and crew to be medically assessed and then be taken into a period of quarantine and monitoring to ensure the control of any infection and provide early medical intervention where needed.”
Oceanwide Expeditions added: “Although hantavirus is usually transmitted to humans via rodents (droppings/urine), the WHO is investigating possible human-to-human transmission on the ship… it is suspected that the first infected person most probably contracted the virus before boarding.”
