What Is Hantavirus? Symptoms, Transmission, and the 2026 Cruise Ship Outbreak Explained

Hantavirus is back in the headlines after a deadly outbreak aboard the MV Hondius cruise ship in May 2026 raised concern around the world. The outbreak led many people to ask what hantavirus actually is, how it spreads, and whether it could become a larger public health threat.

In early May 2026, the World Health Organization confirmed seven hantavirus cases linked to the Dutch cruise ship, including three deaths.

The illnesses began in April and were marked by symptoms such as fever, fatigue, muscle ache, stomach ailments, rapid pneumonia, acute respiratory distress syndrome, and shock.

The outbreak involved the Andes virus, a rare hantavirus strain capable of limited person-to-person transmission.

Health authorities stress that this is not “the next COVID.” Most people will never encounter hantavirus, and the overall global public risk remains low. Still, the outbreak has drawn attention because hantavirus infections can become severe very quickly and carry a high fatality rate.

In this article, we will learn more about Hantavirus, the way it spreads, certain measures, and the symptoms that we must be careful about.

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What Is Hantavirus?

Hantavirus is not a single virus but a family of viruses carried by infected rodents. Different strains exist in different parts of the world, and each is linked to specific rodent species.

In North America, deer mice are the main carriers. In South America, several rodent species carry strains, including the Andes virus. In Europe and Asia, other strains circulate among rodents such as bank voles.

These viruses cause two major illnesses in humans. In the Americas, hantavirus usually causes hantavirus pulmonary syndrome (HPS), which primarily affects the lungs. In Europe and Asia, it more commonly causes hemorrhagic fever with renal syndrome, or HFRS, which primarily affects the kidneys.

The cruise ship outbreak in 2026 involves the Andes virus, which is linked to HPS and is mainly found in parts of South America.

How Hantavirus Spreads — and the Crucial Exception

Most hantavirus infections happen after contact with infected rodents or their waste. Here are a few other common ways it spreads:

• Inhalation: The virus is commonly spread when people inhale tiny airborne particles released from disturbed rodent urine or droppings, especially in enclosed spaces like cabins, sheds, storage buildings, or campsites.
• Contamination: Transmission or infection can also happen when people touch contaminated materials and then touch their eyes, nose, or mouth.
• Rodent Bites: Rodent bites are less common but have also been documented as a source of infection.

We must remember that one reason hantavirus is very different from COVID-19 is that almost none of the hantavirus strains spread easily between humans. The important exception here is the Andes virus, the strain linked to the MV Hondius outbreak.

Limited person-to-person transmission of the Andes virus has been reported during previous outbreaks in South America, especially in Argentina and Chile. During a 2018–2019 outbreak in Argentina, researchers estimated that each infected person passed the virus to just over two others on average before public health measures were introduced. When people were isolated, the transmissions dropped significantly, and were transmitted to just under 1.

To compare, COVID-19 had a reproduction rate of between 1 and 4.

Even so, health experts say that most Andes virus infections still come directly from exposure to rodents rather than from infected people. It spreads only through prolonged, sustained exposure to an infected person.

Symptoms — What Hantavirus Pulmonary Syndrome Looks Like

Hantavirus pulmonary syndrome often begins with symptoms similar to those of the flu or a stomach infection.

Prodromal Phase (days 1–5):

During the early stage of illness, people may develop:

• Fever
• Fatigue
• Headaches
• Dizziness
• Chills
• Severe muscle aches, especially in the thighs, hips, and lower back

Many patients also experience abdominal distress, such as:

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain

Because these symptoms are nonspecific, early hantavirus infection can easily be mistaken for influenza or gastroenteritis.

Cardiopulmonary Phase: The most dangerous part of the illness usually begins several days later. Around day five, some patients’ condition suddenly deteriorates as fluid rapidly builds up in the lungs. This can lead to:

• Severe shortness of breath
• Coughing
• Acute respiratory distress syndrome
• Cardiopulmonary failure

Doctors consider this rapid progression one of the most dangerous features of hantavirus infection. A patient may appear mildly ill one day and critically sick within hours.

The fatality rate remains high. In the United States, hantavirus pulmonary syndrome has historically carried a case fatality rate of roughly 35%. Across the Americas in 2025, health authorities reported 229 cases and 59 deaths, giving a fatality rate of 25.7%.

There is currently no approved antiviral treatment or vaccine for hantavirus. Medical care mainly involves supportive treatment in intensive care settings, including oxygen therapy and careful management of breathing and fluid balance.

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The 2026 Cruise Ship Outbreak — What We Know

On May 6, 2026, investigators confirmed that the Andes virus caused the outbreak aboard the MV Hondius cruise ship in the Atlantic Ocean.

The outbreak comes during an especially severe hantavirus season in Argentina. Since June 2025, the country has recorded 101 confirmed cases, nearly double the number reported during the same period the year before. Argentina has also reported 32 deaths, making it the country’s highest hantavirus burden since 2018.

Researchers believe climate and environmental changes may also be causing this. Warmer temperatures and changing rainfall patterns can encourage plant growth, creating larger food supplies for rodents and allowing their populations to expand.

The outbreak has also highlighted the risk for travelers visiting endemic rural regions in South America, especially people staying in cabins, camping, hiking, or spending time in places where rodent exposure is possible.

Who Is at Risk — and Who Isn’t

Hantavirus risk is highly concentrated in specific environments rather than in the general population.

People at increased risk are those who come into direct contact with rodents or contaminated spaces. This includes rural workers, campers, hikers, people cleaning rodent-infested buildings, and travelers spending time in rural parts of Argentina, Chile, Bolivia, or Paraguay.

By contrast, the risk remains very low for most urban residents and for travelers visiting major cities who do not encounter rodent-infested environments.

WHO data shows that hantavirus infections remain rare worldwide. Across the Americas, only 299 documented cases and 59 deaths were reported during 2025.

In the United States, 890 hantavirus cases were recorded between 1993 and 2023. Most occurred in western states such as New Mexico and Arizona, where encounters between humans and deer mice are more common.

Prevention — What Actually Reduces Risk

Because there is no licensed vaccine, prevention depends entirely on reducing exposure to rodents and contaminated environments.

Health experts recommend sealing holes and gaps in homes, cabins, and storage spaces to prevent rodents from entering. Food should be stored in rodent-proof containers, especially in rural or camping environments.

People cleaning enclosed areas where rodents may have been present should first ventilate the space for at least 30 minutes. We must not dry sweep or vacuum rodent droppings because it can release virus particles into the air. Instead, contaminated areas should be sprayed with a bleach solution and wiped clean while wearing gloves and, in heavily contaminated spaces, an N95 respirator.

Travelers visiting endemic regions of South America are advised to inspect accommodations carefully and avoid sleeping in places with obvious signs of rodent activity.

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Conclusion

Hantavirus is a serious but uncommon infectious disease that remains closely tied to rodent exposure. The 2026 MV Hondius outbreak has attracted global attention because it involves the Andes virus, the only hantavirus strain known to spread between people in limited situations.

At the same time, rising case numbers in Argentina highlight how environmental changes may be affecting rodent populations and increasing human exposure risk. For most people, the overall danger remains very low.

For travelers visiting rural parts of South America, understanding how hantavirus spreads and how to avoid rodent exposure remains the most important protective step. So what can we do? We must protect ourselves by being careful and not panicking.

FAQs

Q. Is hantavirus contagious between people?

Most hantavirus strains are not contagious between people. Infection almost always happens through exposure to infected rodents or their waste. The Andes virus linked to the 2026 cruise ship outbreak is a rare exception because limited person-to-person transmission has been documented in earlier outbreaks.

Q. Is hantavirus dangerous?

Yes. Hantavirus pulmonary syndrome can become severe very quickly and has a high death rate. In 2025, about one in four confirmed cases in the Americas resulted in death. However, infections remain rare and are strongly tied to specific rodent exposure risks.

Q. Should I be worried about hantavirus from the cruise ship outbreak?

WHO says the global public risk from the MV Hondius outbreak remains low. Unless you recently traveled to rural areas of South America or had direct exposure to potentially infected rodents, your personal risk is extremely small.