An outbreak aboard a cruise ship of a rare rodent-borne illness called hantavirus has left three passengers dead and sickened others, with health authorities across four continents trying to track down and monitor passengers who disembarked the ship before its deadly outbreak was detected.
So how dangerous is the virus and how quickly can it spread?
Here’s what you should know and where things currently stand:
What is hantavirus?
According to the U.S. Centers for Disease Control and Prevention, “Hantaviruses are a family of viruses which can cause serious illnesses and death.”
It is “a rare but potentially dangerous rodent-borne virus that can cause flulike symptoms and severe lung or organ problems,” according to Harvard Health.
First detected in the U.S. in 1993, hantaviruses have been around for centuries and are thought to exist around the world.
The disease gained renewed attention last year after the late actor Gene Hackman ’s wife, Betsy Arakawa, died from a hantavirus infection in New Mexico.
Hantaviruses are a family of viruses which can cause serious illness and death, according to the Centers For Disease Control and Prevention.
Where did the outbreak come from?
Detailed investigations of the cruise ship outbreak are ongoing, notably to determine its source.
Investigators in Argentina suspect that the cases were initially contracted during a birdwatching trip in Ushuaia, at the country’s southern tip, two officials told AP.
Argentina has seen a surge of hantavirus cases that many local public health researchers attribute to climate change.
Officials have found evidence of Andes virus, a version of hantavirus found in South America.
The cruise ship outbreak unfolded over weeks on a cruise ship as it sailed across the Atlantic Ocean.
At least three passengers have died and several others are sick and were evacuated from the ship.
A Dutch man was the first to die on board on April 11. On April 24, his wife disembarked the ship, then flew to South Africa a day later and died there. That same day, more than two dozen people from at least 12 different countries left the ship without contact tracing, the ship’s operator and Dutch officials said.
It wasn’t until May 2 that health authorities first confirmed hantavirus had been detected in a passenger, the WHO says. That was in a British man evacuated from the ship to South Africa. He was tested in South Africa and is in intensive care there.
More than 140 passengers and crew members are still aboard the Dutch-flagged MV Hondius as it heads for Spain’s Canary Islands. None of the remaining passengers or crew on the ship are currently symptomatic, the Netherlands-based Oceanwide Expeditions cruise ship company said Thursday.
What makes this strain different?
Tests have confirmed that at least five people who were on the ship were infected with a hantavirus found in South America, called the Andes virus.
The Andes virus is a concerning member of the hantavirus family.
The word hantavirus refers to a broad family of viruses, with different versions in different countries. Almost none of them have been found to spread from person to person — with the possible exception of the Andes virus.
The only hantavirus thought to spread human-to-human, it can cause a severe and often fatal lung disease called hantavirus pulmonary syndrome.
Still, transmission between people does not happen easily, and would require “close and prolonged” contact, according to the WHO.
“We haven’t had huge person-to-person spreads of hantavirus infection ever before, and there’s no reason to suspect a huge outbreak from this case at this point,” said Steven Bradfute, an associate professor and associate director of the Center for Global Health at the University of New Mexico Health Sciences Center, which specializes in hantavirus research.
How worried should you be?
Global health officials say the risk to the general public remains low because the germ does not easily spread between people.
“This is not the next COVID, but it is a serious infectious disease,” said Maria Van Kerkhove, director of epidemic and pandemic preparedness at the World Health Organization. “Most people will never be exposed to this.”
“We believe this will be a limited outbreak if the public health measures are implemented and solidarity is shown across all countries,” said Dr. Abdirahman Mahamud, the WHO’s alert and response director on Thursday.
Dr. Michael Angarone with Northwestern Medicine said it’s not likely the outbreak will become the next pandemic.
“We always have to be careful when we say that. I don’t think it is. I think right now it’s a very isolated encounter,” Angarone told NBC Chicago. “So we have individuals that were in South America, and the assumption is that’s probably where they acquired this virus. And then we’re on this cruise ship where they were intermingling with other people, somewhat intimately, because it’s small ship. And on that ship, the transmissions can occur, and that’s what we think is happening right now. And it’s something to keep an eye on. Most of us think that this is gonna be a limited outbreak. So it’d be very limited to those on the cruise ship, maybe other very close contacts of people that might be exposed outside of that cruise ship. But I think it will kind of peter out over time and won’t be like the pandemic we had with COVID and SARS-CoV-2.”
Still health authorities are tracking down and monitoring passengers who disembarked a hantavirus-stricken cruise ship before its deadly outbreak was detected, and trying to trace others who may have come into contact with them since then.
The virus can incubate for between one and eight weeks. That makes it hard to know whether the passengers contracted the virus before leaving Argentina for Antarctica on April 1; during a scheduled stop to a remote South Atlantic island; or aboard the ship.
Angarone said while there is no shortage of rats in Chicago, hantavirus is not very common in the region.
“We’ve never had a documented hantavirus case in the rats here in Chicago. Most of the hantaviruses that we see here in North America is actually west of the Mississippi,” he said.
“I think this is something that is very rare, but we’re all paying attention to it and monitoring it. And that’s the best thing that we can do is staying informed and knowing everything we can about this and what we need to do. And right now here in Chicago, we’re not at risk of this virus,” he added.
Where have cases been found so far?
The U.N. health agency said the first death onboard, a 70-year-old Dutch man, happened on April 11. His 69-year-old wife, also Dutch, died on April 26. The third passenger, a German woman, died on May 2.
It emerged Wednesday that a man tested positive for hantavirus in Switzerland after he disembarked at St. Helena, though his precise movements in between aren’t clear.
On Thursday, Singaporean health authorities said they were monitoring two men who got off the ship at St. Helena, flew to South Africa and then home. The two men, who arrived in Singapore at different times, were being isolated and tested, officials said.
Authorities in St. Helena, the volcanic British territory in the South Atlantic where passengers disembarked, said they were monitoring a small number of people who were considered “higher risk contacts.” Those higher risk contacts were being told to isolate for 45 days, the St. Helena government said.
The Dutch health ministry said Thursday that a flight attendant on a plane briefly boarded by an infected cruise passenger in South Africa was showing symptoms of hantavirus and would be tested in an isolation ward at a hospital in Amsterdam.
If the Dutch flight attendant tests positive, she could be the first known person not on the MV Hondius to become infected in the outbreak.
WHO epidemiologist Dr. Maria Van Kerkhove commented to pleas for help from online streamers during a hantavirus outbreak. “We are working with many, including everybody on board, to ensure not only do they have medical support… but also providing some psychosocial support as well.”
How does the virus spread?
The virus usually spreads when people inhale contaminated residue of rodent droppings.
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 enclosed spaces with little ventilation or exploring areas with mouse droppings.
What are the symptoms?
An infection can rapidly progress and become life-threatening. Experts say it can start with symptoms including fever, chills, muscle aches and maybe a headache — much like the flu.
Symptoms of hantavirus pulmonary syndrome usually show between one and 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 — known as hemorrhagic fever with renal syndrome, which can cause bleeding, high fever, and kidney failure — usually develops within a week or two after exposure.
Death rates vary by which hantavirus causes the illness. Hantavirus pulmonary syndrome is fatal in about 35% of people infected, while the death rate for hemorrhagic fever with renal syndrome varies from 1% to 15% of patients, according to the CDC.
How common is hantavirus?
Hantavirus infections are relatively uncommon globally. The WHO reported that in 2025, eight countries within the Americas had documented 229 cases and 59 deaths.
Argentina’s health ministry said hantavirus led to 28 deaths nationwide last year. The ministry on Tuesday reported 101 hantavirus infections since June 2025, roughly double the caseload recorded over the same period the previous year.
In the U.S., federal health officials 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 an astute physician with the Indian Health Service who first noticed a pattern of deaths among young patients.
Most U.S. cases are in Western states. New Mexico and Arizona are hot spots, likely because the odds are greater for mouse-human encounters in rural areas.
Is there a treatment for hantavirus?
There is no specific treatment or cure, but early medical attention can increase the chance of survival.
Despite years of research, many questions have yet to be answered, including why it can be mild for some people and severe for others and how antibodies are developed. Some researchers have been following patients over long periods of time in hopes of finding a treatment.
“In the Americas, hantavirus infection is very serious, but it’s also quite rare,” Bradfute said. “And so for a time that probably led to less research into it because of funding priorities, but I know there’s been a lot of interest in funding hantavirus work of late.”
What researchers do know is that rodent exposure is key.
The best way to avoid the germ is to minimize 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 virus particles to get into the air.
