What Is Hantavirus Pulmonary Syndrome?

Written by Jodi Helmer
Medically Reviewed by Jabeen Begum, MD on May 20, 2026

Hantavirus is a group of viruses that spread through contact with infected rats and mice. It causes flu-like symptoms that include fever, fatigue, muscle aches, headaches, chills, and nausea. The symptoms can get worse quickly and may lead to hantavirus pulmonary syndrome (HPS), which can be life-threatening. 

Although hantavirus has been detected in more than 100 species of mammals, rodents are the main carriers. People get the virus from contact with infected mice or rats or breathing air that is infected by their urine, droppings, or saliva. While the virus doesn’t make the rodents sick, it harms the heart, lungs, and kidneys in humans.

Hantavirus infection in humans is rare. From 1993 to 2023, just 890 cases were reported in the United States. It’s even rarer for one person to pass the virus to another person, according to Jonathan Dyal MD, MPH, associate director for global health security at the Johns Hopkins Center for Global Emergency Care.

“It’s a virus that’s transmitted normally between animals and humans,” Dyal says. 

An outbreak in 2026 on the cruise ship MV Hondius involved the especially rare Andes type of hantavirus — the only strain known to be transmittable from person to person.

There is no cure or vaccine for hantavirus. Treatment is based on supportive care. In the U.S., 35% of hantavirus cases are fatal. The earlier it is diagnosed, the better your chances of recovering.

Hantavirus is spread through contact with infected rodents or when exposed to their urine, droppings, or saliva. In rare cases, the virus can spread through a rodent bite or scratch. Person-to-person transmission of hantavirus is rare, but it's possible with the Andes species of the virus.

Cases of hantavirus have been reported in 40 states. It’s more common in western states, with California, Arizona, New Mexico, and Colorado reporting the highest number of infections.

The primary carrier in North America is the deer mouse. Others include:

  • The white-tailed mouse
  • The cotton rat
  • The rice rat

Hantavirus is also found in other countries. The strains common in Europe and Asia can cause hemorrhagic fever and kidney issues instead of lung issues, while the strain common in South America, known as the Andes virus, can be transmitted from rodents to humans or via person-to-person contact with an infected individual.

It is possible for hantavirus to spread from person to person, but it is rare, according to Abraar Karan MD, MS, MPH, an instructor in the Division of Infectious Diseases and Geographic Medicine at Stanford Medicine.

The species that is most common in the U.S. is not known to transmit from person to person. Human transmission of hantavirus is possible with the Andes virus, the species common in South America, and even then, it is still uncommon.

Person-to-person transmission of the Andes virus requires direct physical contact with an infected person, including extended time spent in enclosed or close spaces and exposure to their bodily fluids.

What is the Andes virus?

The Andes virus is the only type of hantavirus known to spread between people. It’s the type detected in the 2026 outbreak of hantavirus on the MV Hondius, which departed from Argentina.

This Andes virus is found primarily in South America, with the highest number of cases reported in Argentina and Chile. 

The long-tailed pygmy rice rat is the primary host for the Andes virus, but other rodent species found in South America, including the southern big-eared mouse, long-haired grass mouse, and olive grass mouse, can also carry the Andes virus. The rodent species that carry the Andes virus have not been found in North America.

“We know that the Andes virus is transmissible between people, but the degree of contact that is required [for the virus to spread] is really high,” Dyal says. “The risk for transmission is greatest among caregivers or close family who are sharing a lot of space ... or health care workers, [but] the risk to the overall public ... is exceptionally low.”

Other types of hantavirus:

There are more than 21 species of hantavirus, including:

  • Hantaan: the striped field mouse in China, Russia, and Korea spreads this species of virus.
  • Prospect Hill: In the U.S. and Canada, meadow voles are the main vectors for this species of hantavirus.
  • Sin Nombre: Deer mice in Alaska and the continental U.S. spread this species of the hantavirus.

Your early symptoms may seem a lot like those of a very bad cold or the flu. You might have a fever and headaches. You may also have:

It can get worse after four to 10 days, when signs of hantavirus include:

Symptoms of hantavirus appear between four and 42 days after exposure. 

Diagnosing hantavirus can be tricky because the symptoms are like those you might see with other viral infections. If you have these symptoms — or they persist or get worse — and you think you’ve been around rats or mice, then see your doctor. They can test your blood for hantavirus or run a polymerase chain reaction (PCR) to diagnose hantavirus.

“PCR testing looks to see if the virus is present in the sample,” Karan says. 

 There is no cure or treatment to kill the virus.

“Treatment is supportive,” Dyal says. “Right now, there are not specific antiviral agents that have been tailored to these viruses.”

When you have hantavirus, you’re generally placed in intensive care in a hospital and given oxygen therapy to support your breathing and clear your lungs of fluid. You might get a breathing tube through your nose or mouth. This is more effective the sooner you are diagnosed and placed into intensive care.

In the most severe cases, people might have their blood pumped through a machine that adds oxygen and takes out carbon dioxide. This is called extracorporeal membrane oxygenation or ECMO. Starting ECMO at the earliest sign of infection has a significant impact on hantavirus survival rates.

Clinical trials are ongoing for potential treatments. Ask your doctor about them if you want to know more. 

Hantavirus: How to seek care

It’s important to seek emergency medical care right away if you have symptoms of hantavirus and have been around rodents or their waste and saliva. 

Patients with hantavirus can become sick very quickly and the virus can be fatal, so early and intensive medical care is essential. Go to the emergency room; do not wait for an appointment with a doctor or a clinic.

Are people quarantined for hantavirus?

The decision about whether to quarantine for hantavirus will depend on the type of the virus.

“The hantaviruses that spread in North America don't spread effectively between people, so [quarantine] is not needed,” says Karan. “The Andes virus does [spread between people] so that does require quarantine.”

The virus can shed for a few weeks after treatment, he adds, so quarantine is decided on a case-by-case basis.

How successful is hantavirus treatment?

Hantavirus causes serious illness. Early supportive care to manage the symptoms and minimize the impact of heart, kidney, and respiratory problems can make treatment more successful. 

The best way to avoid hantavirus is simple: Avoid contact with mice and rats and the areas where they live.

If you live, work, or play in areas that have rodents, be sure to keep your home and work area as clean as possible. Other things you can do:

  • Look for gaps inside or outside of your home and seal holes in structures with cement, wire screens, or metal flashing to prevent rodent infestations.
  • Trap the rodents (use snap traps and not glue traps, which allow them to urinate or leave droppings).
  • Store food in thick plastic, metal, or glass containers with tight lids.
  • Keep garbage in plastic or metal containers with tight lids.
  • Before cleaning cabins, sheds, barns, or other areas where rodents live, open all doors and windows for at least 30 minutes and leave them open during cleaning.
  • Never vacuum or sweep up mouse or rat urine, droppings, or nests because it increases the risk of inhaling the virus.
  • Clean rodent waste: Wear rubber or plastic gloves and an N95 mask. Use household disinfectants or a bleach solution of 1.5 cups of bleach to 1 gallon of water to scrub urine, droppings, and nesting materials.
  • Wash hands with soap and water after handling mouse droppings — even if you wear gloves!
  • Wash all bedding, clothing, or other items with mouse or rat urine or droppings in hot water with laundry detergent.
  • Call an exterminator or your health department if you need more advice or tips.

To prevent human-to-human transmission, Karan advises avoiding close contact with an infected person.

Is there a Hantavirus vaccine?

There is no vaccine for hantavirus.

News of the hantavirus outbreak among cruise ship passengers in 2026 might have some worried about traveling. Dyal offers reassurance.

“We don’t see signs that this outbreak is expanding beyond the ship,” he says. “I don’t think it’s indicative of any greater risk while traveling.”

Spending time outdoors — with a few precautions — is also safe. Before traveling abroad, monitor travel advisories for information about hantavirus risks in destination countries. If you are going hiking or camping, Karan also suggests checking forest service alerts to see if hantavirus is present in the area.

When camping, air out abandoned or seldom-used cabins and check for signs of rodents before settling in. Other ideas:

  • Check the area around outdoor sleeping spots.
  • Don’t sleep on the bare ground; bring a tent with a floor or mat. Better yet, have a cot.
  • Stay away from woodpiles or garbage areas when you bed down.
  • Keep food sealed, including pet food.
  • Burn your garbage following the campsite’s instructions.

Is hantavirus fatal? 

Hantavirus is a serious and potentially fatal disease, but early supportive care in an intensive care setting can improve survival rates.

Why should I not vacuum mouse droppings? 

Vacuuming mouse droppings increases the risk of inhaling the virus. It’s safer to spray droppings with a disinfectant solution, let it soak, and wipe it up (while wearing gloves and a mask).

Can pets transmit hantavirus to humans? 

Pets might bring infected rodents into homes, but in the U.S., dogs and cats don’t appear to become infected with the hantavirus or spread it to humans.

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