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Three passengers on a cruise ship in the Atlantic Ocean have died after a suspected hantavirus outbreak, according to the World Health Organization (WHO).
The outbreak was reported on the polar cruise ship MV Hondius, which was travelling between Argentina and Cape Verde.
The WHO said at least one case of hantavirus had been confirmed, with one patient in intensive care in a South African hospital. Two of those who died were a couple from the Netherlands.
What is hantavirus?
Orthohantaviruses, more commonly known as hantaviruses, are a group of viruses primarily found in rodents, but which can infect humans.
According to Prof Adam Taylor of Lancaster University, there are at least 38 recognised species of hantavirus globally, 24 of which cause disease in humans. Rodents such as mice, rats and voles are the natural reservoirs for the viruses.
Dr Yomani Sarathkumara, a postdoctoral research fellow at the University of Queensland, said hantavirus infections were “really rare in humans”, and were often misdiagnosed in tropical countries as other infections, such as leptospirosis, which is also spread by animals.
How is the virus spread and what are the symptoms of hantavirus?
Hantaviruses are spread to humans via inhalation of or contact with infected rodent faeces, urine and saliva – or, more rarely, through bites and scratches from contaminated animals.
“Agricultural communities across the world are at higher risk,” Sarathkumara said – as a result of higher likelihood of exposure to infected rodents.
Associate Prof Vinod Balasubramaniam, a molecular virologist at Monash University Malaysia, said hantaviruses were “typically an environmental exposure linked to rodents”, and “do not usually spread easily from person to person in the way that you see flu or Covid-19 does”.
There are two major lineages of hantavirus: old world hantaviruses and new world hantaviruses.
Old world hantaviruses are found in Europe and Asia – these include puumala hantavirus, Hantaan virus, and Seoul virus. In humans, they typically cause haemorrhagic fever with renal syndrome (HFRS), which affects the kidneys. Symptoms can include intense headaches, back and abdominal pain and fever, and potential kidney damage.
New world hantaviruses are found in the Americas, and usually cause hantavirus pulmonary syndrome. The most common type in South America is the Andes virus, which is primarily spread by the long-tailed pygmy rice rat.
“New world hantaviruses cause really rapidly progressive pulmonary syndrome and respiratory failure,” Balasubramaniam said. Early on, an infection may cause flu-like symptoms such as fever, fatigue and muscle aches, which makes “early diagnosis really difficult”, he said.
In March 2025, Betsy Arakawa, the wife of actor Gene Hackman, was found to have died in their Santa Fe home from hantavirus pulmonary syndrome, prior to the death of her husband, who had Alzheimer’s, in the absence of her care.
Hantaviruses can have long incubation periods – between one and eight weeks long, Balasubramaniam said.
According to Taylor: “A small number of studies have documented human-to-human spread of the Andes strain in South America, but a systematic review of the research didn’t find enough evidence of human-to-human transmission.”
How did the hantavirus outbreak on the cruise ship occur?
The WHO said an investigation into the suspected hantavirus outbreak on MV Hondius was under way. Though we don’t yet know exactly how it occurred, Balasubramaniam said: “There are a couple of biologically plausible possibilities.”
The first is the possibility of rodent contamination in the vessel itself – “if infected rodents had access to storage areas … cabins and other enclosed spaces”.
The second is – because of the long incubation periods of hantaviruses – that the outbreak “might not have necessarily originated from the ship itself”, Balasubramaniam said. “Passengers or crew members could theoretically be exposed during land-based activities.”
The third – but least likely – is person-to-person transmission. “This is plausible theoretically but it’s highly [unlikely],” Balasubramaniam said.
“The main risk is disturbing contaminated rodent materials … in close or poorly ventilated spaces,” he said. “The risk is not usually from just sharing [the] same space of air with an infected person.”
What is the mortality rate for hantavirus? Is there a treatment?
Fatality rates from HFRS, caused by the old world hantaviruses, are estimated to be between 1% and 15%.
“New world hantaviruses … cause much more severe symptoms and the chances of mortality are much, much higher,” Balasubramaniam said. Hantavirus pulmonary syndrome has a fatality rate of about 40% in the Americas.
“We don’t have a definitive antiviral [drug] that works really well,” Balasubramaniam said. Infections were typically treated with supportive management, which made early diagnosis important, he added. However, broad-spectrum antivirals are being researched for use as an early treatment.
For hantavirus pulmonary syndrome, supportive care includes oxygen, fluid management, blood pressure support and ventilation.
Credit:Guardian News
