What is hantavirus and how does it spread? Key questions after outbreak

The cruise ship hit by an outbreak of hantavirus is on track to dock in the Canary Islands by the weekend.

Three people confirmed to have the virus and five suspected cases have been linked to the ship - the MV Hondius.

The confirmed cases are a Dutch woman who died, a British passenger in intensive care in South Africa and a Swiss passenger who is being treated in a Zurich hospital.

A British man, a Dutch crew member and a German national are among the suspected cases. Two have arrived in the Netherlands for treatment while a third, who is in a stable condition, is on board an evacuation flight that has been delayed.

None have tested positive for hantavirus, but two have shown symptoms.

Two other British passengers are isolating at home after potential exposure to the virus.

They left the ship, which was travelling from Argentina across the Atlantic to Cape Verde, earlier in its journey and have not shown symptoms, the UK's Health Security Agency said.

Authorities in two US states, Arizona and Georgia, have confirmed to the BBC they are monitoring three passengers who had returned to the US after disembarking the cruise before it reached Cape Verde. None are displaying symptoms.

All up, 146 people from 23 countries remain on the MV Hondius as it sails to the Canary Islands, where they will be medically assessed before being able to travel home.

What is the Andes strain of hantavirus?

Hantaviruses, which are named after a river in South Korea, describe a family of viruses rather than one single disease.

There are more than 20 different viral species, according to the World Health Organisation (WHO) - almost all of them linked to infection by rodents, typically rats and mice, through dried urine and droppings.

But one strain, known as Andes virus, is thought to spread by human-to-human transmission, although very rarely. It has been confirmed in two passengers – the British man in hospital in Johannesburg and the Dutch woman who died – according to South Africa's health minister.

The Andes virus is mostly found in Argentina and Chile.

In late 2018, there was an Argentinian outbreak that was traced back to people who had attended a party – a single person with the virus is thought to have unwittingly spread the virus to 34 confirmed cases, with 11 deaths.

How does this change what happens next?

The WHO has been working on the assumption that the virus could be spreading through very close contact from person to person on the ship and through contact with rodents.

Now the Andes virus is confirmed, it becomes even more important for passengers and crew on board the ship to observe the sort of social distancing we grew used to in the Covid pandemic.

Passengers are currently confined to their cabins to limit exposure, so that will help.

Experts say that measures such as isolating infected patients, regular handwashing, tracing and monitoring close contacts and applying infection control measures will all be critical to stopping the spread of the disease.

It is still not clear how the outbreak started. A Dutch couple who have died had travelled in South America before boarding the ship at the beginning of April. It is possible one or both of them came into contact with the virus during their travels.

The cruise had been visiting remote wildlife areas, so there is always the possibility a passenger came into contact with the virus during the cruise.

Further genetic testing of the virus may be able to narrow down how it got on board in the first place.

Experts say the risk of infection for the global population is very low. At present, there is no evidence of spread beyond the ship.

How does hantavirus spread?

It's normally spread when people come into close contact with droppings, urine and saliva from rodents.

This usually happens by breathing in the virus, for example when rodent urine and droppings that contain hantavirus are stirred up into the air.

The virus can also be caught from a bite from a rodent, such as a rat.

Only one strain is known to spread from person to person, although very rarely - the Andes strain.

Where there is person-to-person transmission, it is through very close, prolonged contact with someone with symptoms.

The way hantavirus spreads is different to flu, which is transmitted through droplets when people cough or sneeze.

"We're not talking about casual contact from very far away from one another," WHO official Dr Maria van Kerkhove told the BBC.

What are the symptoms and how deadly is hantavirus?

The virus can cause two severe illnesses. The first, Hantavirus Pulmonary Syndrome (HPS), often starts with fatigue, fever, and muscle aches, followed by headaches, dizziness, chills, and abdominal issues.

But it is possible that respiratory symptoms then develop – severe breathing difficulties – and at that point patients need urgent medical attention.

This is one of the main illnesses caused by the Andes strain, with a mortality rate of 20-40%.

The incubation period for the disease is also a complicating factor – it can take anywhere between one and eight weeks for symptoms to appear.

The second illness, Haemorrhagic Fever with Renal syndrome (HFRS), which starts looking like the flu, can go on to affect the kidneys and lead to low blood pressure, internal bleeding, and acute kidney failure.

Elton Monteiro / EPA

Is there a vaccine or treatment for hantavirus?

There is no specific treatment for hantavirus infections - but early medical support can improve survival.

The type of care recommended can include oxygen therapy, mechanical ventilation and even dialysis.

Patients who are very ill with severe symptoms may need to be admitted to hospitals and treated in intensive care units.

New treatments are being trialled.

There are currently no widely available vaccines to protect against the virus. However, some are being used in China and South Korea against strains that are common there.

How many cases of hantavirus are reported globally?

There are an estimated 150,000 cases of HFRS worldwide each year, primarily in Europe and Asia, according to a report from the National Institutes of Health. More than half of the reported cases typically occur in China.

The latest data from the US shows that there were 890 cases of hantavirus in the country from 1993-2023.

Have there been recent hantavirus cases?

In February 2025, Betsy Arakawa, the wife of Oscar-winning actor Gene Hackman, died from a respiratory illness linked to hantavirus.

Medical investigators believe Arakawa contracted HPS - the most common strain in the US - which led to her death.

Nests and some dead rodents were found in outbuildings of her house where she was found.

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