What is hantavirus? The rare virus linked to a deadly cruise ship outbreak
Hantavirus is a rare but deadly virus that has been linked to a deadly cruise ship outbreak in the southern Atlantic. Should we be worried?
- 4 May 2026
- 6 min read
- by Linda Geddes
Three people have died and several others are unwell following a suspected outbreak aboard a cruise ship, now docked off Cape Verde in the Atlantic.
At least one case has been confirmed as hantavirus: a rare but potentially deadly infection usually linked to exposure to infected rodents.
The ship, the MV Hondius, had been at sea for around three weeks when passengers began to fall ill. Yet, with an incubation period of typically one to eight weeks, pinpointing where exposure to this virus may have occurred could prove difficult.
What is hantavirus?
Hantavirus refers to a group of viruses that are usually carried by rodents such as rats and mice, but which occasionally cause severe infections in humans.
This typically follows contact with, or inhalation of, particles from their droppings or urine. It does not usually spread from person to person, although this has been documented in rare cases linked to specific strains.
Hantaviruses are broadly divided into two groups. The first is Old World hantaviruses, found in Africa, Asia and Europe, which can cause haemorrhagic fever with renal syndrome (HFRS), a severe kidney disease.
New World hantaviruses, found in the Americas, can cause a lung disease known as hantavirus pulmonary syndrome (HPS).
Both forms of hantavirus infection typically begin with flu-like symptoms before in some cases progressing to more serious illness. When this happens, the consequences can be severe: HFRS has a fatality rate of 5–15%, while for HPS it is between 35% and 50%.
“While these are life-threatening, most hantavirus infections do not progress to this stage of disease, and they are more likely to do so in people with underlying health conditions,” said Dr Liam Brierley at the MRC-University of Glasgow Centre for Virus Research, UK.
“Certain specific hantaviruses are also milder than others, though it is currently hard to speculate, as we don’t yet know which of these diseases or which specific hantaviruses affected the people on the MV Hondius. So far, only one case has been confirmed positive for hantavirus at all.”
How might cruise passengers have been exposed?
The MV Hondius is a Dutch-flagged vessel that left Argentina about three weeks ago on a voyage that included stops in Antarctica, the Falkland Islands and other locations. Around 150 passengers are thought to be on board, along with roughly 70 crew members.
Assuming the cases are all caused by hantavirus, there are several possible routes of exposure.
One is that passengers were exposed while on a shore excursion, particularly in areas where contact with rodents or their droppings is more likely.
Another is that rodents could have entered the ship via cargo or supplies, contaminating enclosed spaces such as storage areas or ventilation systems.
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Infection would most likely occur through the inhalation of viral particles from infected urine or droppings or, less commonly, through contaminated food.
“Importantly, hantaviruses are not transmissible from person to person except in extremely rare circumstances and only for one specific type of hantavirus called Andes virus, under very intensive close contact – for example, between sexual partners or from hospital patient to hospital staff,” said Brierley.
“It’s therefore extremely likely that these cases have resulted from the same single point of exposure to rodents. The long incubation period means that it will be challenging to pinpoint exactly when and where this occurred.”
Much remains uncertain. However, “given the ship came from South America, it is plausible that the Andes strain of the virus may be responsible for this outbreak,” said Dr Michael Head, a senior research fellow in global health at the University of Southampton, UK.
If so, this wouldn’t necessarily mean the virus was spreading from person to person. While the Andes strain can be transmitted between humans, this is rare. Most cases are still linked to exposure to infected rodents. PCR testing would be needed to confirm whether this is the Andes strain.
How common are hantavirus outbreaks?
Globally, an estimated 100,000 to 200,000 hantavirus infections occur each year. The majority of these cases are in Asia, particularly China. Most are sporadic or occur in small clusters, linked to contact with infected rodents.
“It is usually associated with cleaning or dusting properties that have been dormant over winter where rodents have encroached into the property,” said Dr Benjamin Brennan, also at the MRC-University of Glasgow Centre for Virus Research.
However, larger outbreaks have occasionally been recorded. One of the most notable is the 1993 ‘Four Corners’ outbreak in the southwestern US, which helped establish hantaviruses as a cause of severe human disease.
During this outbreak, about 33 people were infected and 13 died. The outbreak was traced to several species of rodents but particularly deer mice, the population of which had increased approximately ten-fold since the previous year.
There is no specific treatment or cure for hantavirus and care is therefore largely supportive. However early medical intervention can improve chances of survival.
Rodents were found in victims’ households and an investigation found that these individuals were also more likely to thoroughly clean their homes and work in their gardens than average, potentially bringing them into contacted with infected dust or soil.
Eventually, a previously unknown hantavirus, named Sin Nombre virus, was found to be the cause.
In 1996 another outbreak of hantavirus pulmonary syndrome occurred in the Argentinian city of El Bolsón, which involved 16 linked cases and spread to nearby areas.
The cause was a known hantavirus, Andes virus, but during this outbreak researchers identified evidence of limited person-to-person transmission.
More recently a detailed investigation of a 2018-19 outbreak, also in Argentina, found that the virus could spread between people through close contact, including during crowded social events.
Even so, such transmission appears to be uncommon and requires specific conditions. Most hantavirus infections are still linked to direct exposure to infected rodents.
What happens next?
Given the long incubation period, it is possible that more cases could emerge in the coming weeks.
Hans Kluge, the World Health Organization’s regional director for Europe, said WHO was acting with urgency to support the response, working with affected countries on medical care, evacuations, epidemiological investigations and a public health risk assessment.
There is no specific treatment or cure for hantavirus and care is therefore largely supportive. However early medical intervention can improve chances of survival, including oxygen therapy, mechanical ventilation or, in some cases, dialysis.
There is currently no widely available vaccine against hantavirus. While inactivated vaccines against Hantan and Seoul viruses, two causes of haemorrhagic fever with renal syndrome (HFRS), are used in China and South Korea, their effectiveness is uncertain. There is no globally licensed vaccine for all forms of the disease, particularly hantavirus pulmonary syndrome (HPS).
For now, health officials say the risk beyond those directly affected remains low. “There is no need for panic or travel restrictions,” Kluge said.
