Could the Hantavirus Lead to a Pandemic? Experts Explain the Risk Level

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A total of eight cases, including three deaths, have been reported in connection with Hantavirus, a rare but dangerous virus carried by rodents, amid an ongoing outbreak on a cruise ship in the Atlantic Ocean, prompting concerns about a possible pandemic and comparisons to COVID-19.

Health authorities across multiple countries are rushing to trace contacts of the sick passengers and control the outbreak, which began on the MV Hondius in early April.

However, all of the experts TODAY.com spoke with stress that this situation is not similar to COVID, both due to the type of virus involved and ongoing containment efforts.

“While this is a serious incident, (the World Health Organization) assesses the public health risk as low,” WHO chief Dr. Tedros Adhanom Ghebreyesus said in a press briefing on May 7.

After being stranded off the coast of Cabo Verde, the Spanish government announced it would accept the hantavirus-stricken ship. The MV Hondius is currently heading to the Canary Islands, where it will dock in Tenerife on May 10.

The Americans on board will be met by a team from the U.S. Centers for Disease Control and Prevention and escorted to the National Quarantine Unit in Omaha, Nebraska, the University of Nebraska Medical Center said in a press release.

In the meantime, health officials are investigating how the ultra-rare virus made its way onto the luxury cruise ship and spread among passengers.

Hantaviruses are a group zoonotic viruses that can cause severe disease and death in humans. They’re not new, but outbreaks of hantavirus are very uncommon, Dr. Carla McWilliams, chair of the division of infectious diseases at the Cleveland Clinic in Florida, tells TODAY.com.

Additionally, the strain of hantavirus involved in the cruise ship outbreak is even more uncommon, according to experts. Here's what to know about the outbreak:

2026 Hantavirus Cruise Ship Outbreak

On May 4, the WHO confirmed a cluster of hantavirus cases on the MV Hondius. Of the nearly 150 people aboard, eight suspected or confirmed cases of hantavirus have been identified so far, including three deaths.

Authorities are also investigating a potential case linked to the cruise in a man on the remote island of Tristan Da Cunha.

Three of the sick passengers have been medically evacuated to the Netherlands. One patient is critically ill and being treated in an intensive care unit in South Africa, where laboratory testing first identified hantavirus on May 2, per the WHO.

Another case was confirmed in Switzerland in a man who left the MV Hondius voyage early, before the outbreak was identified.

The cruise originally departed from Ushuaia, Argentina, on April 1 and made stops in Antarctica and several remote islands in the South Atlantic. It was near the waters of St. Helena island in mid-April when passengers began falling ill and the first person died.

On April 24, some 30 passengers — including 8 Americans — disembarked in St. Helena after the death on board, about one week before hantavirus was detected, cruise operator Oceanwide Expeditions said in a statement.

Authorities in Georgia, Arizona, California, Texas and Virginia have confirmed they are monitoring residents who left the cruise early and have since returned home. So far, none are showing symptoms, NBC News reported.

Two New Jersey residents who were potentially exposed to an infected passenger during air travel are also being monitored, but neither are symptomatic, state officials said.

The remaining Americans on the MV Hondius will be quarantined and monitored in Nebraska. “We are prepared for situations exactly like this. Our teams have trained for decades,” Dr. Michael Ash, CEO of Nebraska Medicine said in a release.

As officials race to contain the deadly outbreak, the WHO announced that the virus may have spread from person-to-person through a rare strain called the Andes virus.

What Is the Andes Strain of Hantavirus?

At least 20 strains of hantavirus are known to cause disease in humans, Kari Moore Debbink, Ph.D, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, tells TODAY.com.

Most hantaviruses spread to people through contact with infected mice and rats or their feces, urine or saliva, often by inhaling aerosolized droppings, per the CDC.

"That's the normal route in almost all cases," says Debbink.

Andes hantavirus, which is found in South America, mainly in Argentina and Chile, is unique in that it’s the only species known to cause human-to-human transmission, Dr. Mara Jana Broadhurst, a pathologist at Nebraska Medicine and member of the College of American Pathologists’ Microbiology Committee, tells TODAY.com.

It spreads primarily to humans from the pygmy rice rat, but can also transmit between people through close, prolonged contact.

“The precise mechanism of transmission between people has not been definitively established,” says Broadhurst, adding that Andes virus has been detected in blood, saliva, urine and semen.

Only a small number of cases of the Andes strain involving clear human-to-human transmission have been documented. "These are mostly cases in people who were either living together or health care workers treating sick people," Debbink adds.

The cruise ship departed from Southern Argentina, where the Andes virus is endemic. Sequencing of virus samples from at least one passenger confirmed the Andes strain, the WHO said.

“Our assumption is (people) were infected off the boat and then joined the cruise,” Maria Van Kerkhove, epidemiologist and WHO technical advisor, said at a press briefing on May 5.

"We do believe that there may be some human-to-human transmission that’s happening among the really close contacts," Van Kerkhove added.

However, it’s unclear how exactly each passenger was exposed.

“I think part of the reason why this is novel is because it looks like there’s possibly human-to-human transmission beyond an isolated case or a small family outbreak,” Debbink says.

The WHO’s investigation is ongoing.

What Is the Risk to the Public?

While hantavirus is dangerous, experts say the general public doesn't need to worry.

Based on available information, the WHO currently assesses the risk to the global population from this outbreak to be low.

In a May 7 statement, the CDC said that “at this time, the risk to the American public is extremely low.”

Debbink agrees: “Historically with the Andes virus, it’s spread between people in close proximity, so the risk of this transmitting more widely is pretty low.”

In the past, hantavirus hasn’t caused widespread outbreaks involving human-to-human transmission. One of the largest documented Andes virus outbreaks occurred in 2018 in Patagonia, Argentina and resulted in 34 cases and 11 deaths.

There’s no reason to believe that the Andes virus has mutated into a more transmissible variant, Dr. Ashish Jha, a senior fellow at Harvard University’s Kennedy School, said on TODAY on May 7.

The current cluster could result in additional cases among cruise passengers, Broadhurst notes, and secondary transmission among their close contacts is possible, but the risk of widespread transmission remains low.

The WHO is working with the cruise staff, health authorities from countries involved and airlines to conduct contact tracing for passengers who left the ship early.

No additional passengers, beyond the eight cases already identified, have reported feeling sick with hantavirus symptoms.

Due to the long incubation period, officials will continue to closely monitor everyone who was potentially exposed.

"Personally, I’m not worried. There's been a very swift and prompt response to all of this, so hopefully the public feels reassured that there's a plan in place," says McWilliams.

Once the ship docks, there will be a full epidemiological investigation and disinfection. All passengers will be screened and anyone who shows symptoms will be isolated, the WHO said.

While the situation aboard seems terrifying, some passengers are painting a calmer picture.

“People are taking the situation seriously but without any panic, trying to keep social distancing and wearing masks to be safe,” travel blogger Kasem Hato, said in a statement sent to NBC News.

Will the Hantavirus Cause a Pandemic, Like COVID?

If you're wondering if hantavirus will become the next COVID, the answer from experts is no.

“I don’t think people need to be terrified that this is all of a sudden going to start a pandemic. I would be absolutely shocked if that happened,” says Debbink.

“This is not a COVID situation. I think they’re going to be able to contain the cases,” she adds.

SARS-CoV-2, the virus that causes COVID, spreads very efficiently between people through respiratory droplets, Broadhurst notes. The Andes hantavirus behaves very differently. “It does not spread easily between people,” Broadhurst adds.

In a press briefing on May 7, WHO officials reassured the public that they predict a limited outbreak that will be contained.

Andes Strain Hantavirus Symptoms

Hantavirus can cause two distinct types of disease, depending on the strain, says Debbink.

The Andes strain, along with other hantaviruses in the Americas, cause hantavirus pulmonary syndrome (HPS), a severe and often fatal respiratory illness, says Broadhurst.

The incubation period is long, says Debbink. Symptoms of HCPS can take one to eight weeks to appear after exposure.

Early symptoms of HPS include:

After four to 10 days, these flu-like HPS symptoms progress to:

“The fatality rate of HPS is 30-40%,” says Debbink. There is no specific treatment or cure for HPS, other than supportive care.

The sick passengers aboard the MV Hondius mostly reported flu-like illness and gastrointestinal symptoms, per the WHO. Some remained mild, and others progressed rapidly to respiratory distress or pneumonia.

Hantaviruses found in Europe, Asia and Africa cause a different disease, hemorrhagic fever with renal syndrome (HFRS).

HFRS often starts with similar flu-like symptoms but progresses to internal bleeding and kidney failure — it’s more common than HPS, but the mortality rate is lower (less than 15%), says Debbink.

How to Reduce the Risk of Hantavirus

There aren't any special precautions the public needs to take to protect against the Andes strain, the experts note.

"This isn't something people need to be worried about being exposed to. I wouldn't cancel a cruise," says Debbink.

Most people will never be exposed to this virus, the experts note.

However, you can reduce your risk of contracting all hantaviruses by minimizing your exposure to wild rodents, especially species known to carry hantavirus.

In the U.S., the main culprit is the deer mouse, per the CDC.

People usually get hantavirus from inhaling aerosolized particles from feces, urine or saliva, Debbink points out.

Always seal holes and gaps in the home where rodents can enter or nest. When cleaning up droppings, avoid vacuuming or sweeping. Instead, wipe them up with a wet paper towel and a bleach solution.

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