What is hantavirus? Outbreaks, symptoms, diagnosis, prevention

Hantaviruses are RNA viruses carried by rodents. They belong to the family Hantaviridae. 

• In the Americas, they cause a severe lung disease called Hantavirus Cardiopulmonary Syndrome (HCPS), also known as Hantavirus Pulmonary Syndrome (HPS) [3]. 
• In Europe and Asia, they cause a serious kidney disease called Hemorrhagic Fever with Renal Syndrome (HFRS) [3].

HCPS is one of the most lethal rodent-borne diseases recorded. Case fatality rates in the Americas reach up to 50% [3, 4].

HFRS is generally less deadly, but outcomes vary widely by strain, from less than 1% for Puumala virus to as high as 15% for Hantaan virus [5, 6, 25]. 

Hantavirus as a bioterror agent

The US CDC (Centers for Disease Control and Prevention) lists hantaviruses as Category C bioterrorism agents because certain strains could potentially be aerosolized and used to cause mass harm.

Overview

Hantavirus is spread by rodents, including rats and mice. Humans can get infected with the hantavirus by breathing in air infected with the virus particles from rodent droppings, urine, or saliva. 

The virus can even enter the body through cuts or rarely, through rodent bites. 

Hantavirus does not spread from person to person except in rare cases. A particular strain of Hantavirus, called the Andes hantavirus has been known to spread between people in close contact.

HFRS

All known HFRS-causing hantaviruses spread through contact with infected rodents or their droppings, urine, and saliva. Human-to-human transmission has not been documented for any HFRS-causing strain [3, 8].

Specific routes include:

• Breathing in airborne particles from infected rodent droppings, urine, or saliva
• Touching the eyes, mouth, or nose after contact with contaminated surfaces
• Bites from infected rodents (relatively uncommon)

HCPS

Most hantaviruses that cause HCPS also do not spread between people. The Andes virus is the one known exception. Even then, it requires close and prolonged contact with someone who is already sick [1].

According to the US CDC, documented routes include direct physical contact, spending extended time in close or enclosed spaces together, and exposure to the sick person’s saliva, respiratory secretions, or other body fluids [9].

The 2026 MV Hondius cluster was the first documented multi-case outbreak in a non-endemic setting, with evidence of person-to-person transmission occurring outside South America [8, 26].

Hantavirus disease appeared in Chinese medical writing approximately 1,000 years ago [27]. It drew global attention during the Korean War (1950 to 1953), when more than 3,000 United Nations service members fell ill with a severe febrile illness that doctors at the time called Korean Hemorrhagic Fever [10].

It took more than two decades to identify the pathogen behind it. In 1976, Ho Wang Lee and colleagues identified a previously unknown antigen in the lung tissue of striped field mice (Apodemus agrarius) in South Korea.

In 1978, the team isolated the virus itself from blood samples of hemorrhagic fever patients, confirming it as the pathogen responsible [10, 28]. In 1980, this novel virus was formally named Hantaan virus, after the Hantaan River near the demilitarized zone where the original rodent samples had been collected [28].

In 1982, WHO used the term Hemorrhagic Fever with Renal Syndrome to capture the range of illness this group of viruses could cause. By 1984, all viruses causing HFRS were formally grouped under the genus Hantavirus [3].

A second group of hantaviruses emerged in the early 1990s in the Americas. These cause lung disease, not kidney disease.

In the United States, this illness was first identified in 1993 in the Four Corners region, where Arizona, Colorado, New Mexico, and Utah meet [3]. The virus was eventually named Sin Nombre, Spanish for “without name,” after residents objected to having a disease named after their region.

More than 40 hantavirus strains have been identified to date, of which approximately 20 are known to cause disease in people [29].

Old World hantaviruses, which cause HFRS, circulate mainly in Europe and Asia. New World hantaviruses, which cause HCPS, are found only in North and South America [3]. 

HFRS: Hemorrhagic Fever with Renal Syndrome

Global estimates of annual HFRS cases vary considerably across sources, ranging from 100,000 to as many as 200,000 per year [4, 11]. The true burden is likely higher, since the disease is often undetected or unreported in many countries.

Cases tend to cluster during dry seasons: late spring, fall, and sometimes early winter. People who spend a lot of time outdoors or near rodent habitats, including farmers, soldiers, forestry workers, and construction workers, are at greatest risk [3].

China accounts for 70 to 90% of all HFRS cases reported worldwide [12, 13]. Incidence has declined significantly since the 1980s, following vaccination programs and prevention measures. Between 2014 and 2023, approximately 91,000 cases were reported nationally, an average of around 9,000 per year, with annual totals ranging from roughly 5,000 to 12,000 [29a]. Most cases are caused by the Hantaan virus (HTNV) and Seoul virus (SEOV). HTNV-associated HFRS is the more severe form, with a case fatality rate as high as 15% [5, 14].

Russia reported 131,590 HFRS cases between 2000 and 2017 [15]. Puumala virus is responsible for approximately 97% of all Russian HFRS cases and dominates across Western Russia. Dobrava virus is present in limited areas, primarily the Sochi district of southern Russia [15]. Eastern Russia sees more cases associated with the Hantaan and Seoul viruses.

Europe reports more than 10,000 HFRS cases a year, most caused by Puumala virus, which is carried by bank voles [16]. Puumala infections tend to be mild, with a case fatality rate below 1% [5, 6]. Finland has the highest case count in Europe, with 1,000 to 3,300 serological diagnoses per year [16, 17]. WHO reported 1,885 hantavirus infections across Europe in 2023, the lowest figure recorded in that region between 2019 and 2023 [8].

HCPS: Hantavirus Cardiopulmonary Syndrome

More than 20 hantavirus strains in the Americas are known to cause HCPS [29]. Sin Nombre virus is the most common cause in North America. Andes virus causes most cases in South America [3].

In 2025, eight countries in the WHO Americas region reported 229 confirmed HPS cases and 59 deaths, a death rate of 25.7%. These figures cover data through epidemiological week 47 of 2025 [8]. In Argentina alone, more than 100 cases were recorded between June 2025 and early May 2026, roughly double the previous year’s total, according to Argentina’s Ministry of Health.

From 1993 through 2023, 890 laboratory-confirmed cases of hantavirus disease were reported in the United States, according to CDC surveillance data [18].

Notable Outbreaks

• 1951 to 1953, Korean Peninsula: More than 3,200 United Nations soldiers fell ill with Korean Hemorrhagic Fever during the Korean War. Approximately 467 died, a case fatality rate of around 14.6%. The virus, later named Hantaan, was not identified until 1976 [10, 28].
• 1993, Four Corners, United States: The first recognized HCPS outbreak in the Americas. A total of 48 laboratory-confirmed cases were reported nationally, with 27 deaths, a case fatality rate of 56%. The outbreak led to the discovery of Sin Nombre virus and established HPS as a distinct clinical entity [3, 18].
• 1996 , El Bolsón, Argentina: The first documented cluster of person-to-person Andes virus transmission. This small outbreak in Rio Negro Province, Patagonia, established that the Andes strain could spread between people under conditions of close contact, a finding unique among hantaviruses [1].
• 2012, Yosemite National Park, United States: Ten visitors who had stayed in insulated tent cabins in Curry Village developed HPS after exposure to deer mice in cabin wall insulation. Three died. Rodent trapping found Sin Nombre virus antibodies in 14% of captured deer mice. All implicated cabins were subsequently demolished [30].
• 2018 to 2019, Epuyén, Argentina: A single index case linked to rodent exposure attended a social gathering while symptomatic, triggering a chain of person-to-person transmission. By the end of the outbreak, 34 people had been confirmed infected and 11 had died. The event was documented in a landmark study in the New England Journal of Medicine and became a reference case for Andes virus person-to-person transmission dynamics [31].
• 2026, MV Hondius cruise ship, multi-country: An Andes virus outbreak aboard a Dutch-flagged cruise ship that had departed Ushuaia, Argentina on April 1, 2026, carrying 147 passengers and crew from 23 countries. As of May 19, 2026, 11 cases (9 confirmed, 2 probable) and 3 deaths had been reported. This was the first documented multi-case Andes virus outbreak in a non-endemic setting, with evidence of person-to-person transmission occurring outside South America [8, 26].

Hantavirus infections begin when a person inhales tiny airborne particles from the droppings, urine, or saliva of an infected rodent. Once inside the body, the virus travels to the cells lining the walls of blood vessels, called endothelial cells. These are its primary targets [3, 32].

The virus infects these cells but leaves them structurally intact. Instead of destroying them, it changes how they function. Infected endothelial cells become abnormally leaky, allowing fluid to seep out of blood vessels and into surrounding tissue. This leakage is driven mainly by the body’s immune response to the infection [32].

Where that fluid accumulates determines the type of disease. In HCPS, it collects in the lungs, making breathing progressively harder. In HFRS, it collects in and around the kidneys, causing acute kidney failure. Both can be fatal [3].

How the virus travels from the respiratory tract to blood vessels throughout the body is still being studied. The most supported explanation is that it enters the bloodstream and spreads from there. Infected immune cells may also carry it to other organs [32].

How severe the illness becomes depends largely on the specific hantavirus strain involved. Hantaan and Andes infections cause the most serious disease. Puumala infections are generally much milder [3].

Hantavirus symptoms vary depending on which disease a person develops. The two syndromes, HFRS and HCPS, affect different organs and follow different clinical courses. 

HFRS

How sick a person gets with HFRS depends heavily on the virus involved. Hantaan and Dobrava infections cause the most severe illness. Seoul, Saaremaa, and Puumala infections tend to be milder [5].

Symptoms typically appear two to four weeks after exposure, though the range runs from one week to as long as eight weeks in rare cases [5, 6].

The illness typically begins suddenly with:

• Severe headaches
• Body and back pain
• Fever and chills
• Blurred vision
• Nausea
• Facial flushing (less common)
• Eye inflammation or redness (less common)
• Rash (less common)

As hantavirus-associated HFRS progresses, it can cause dangerous drops in blood pressure, fluid leaking from blood vessels into surrounding tissue, and acute kidney failure with severe fluid buildup in the body [5, 6].

HCPS

In HCPS, hantavirus symptoms typically appear one to eight weeks after exposure [9]. The early phase feels a lot like the flu: fatigue, fever, and muscle aches, especially in the thighs, hips, and back, and sometimes the shoulders.

About half of people with HCPS also develop headaches, dizziness, chills, nausea, vomiting, diarrhea, and stomach pain [3].

Four to ten days into the illness, the disease can turn serious quickly. A cough develops, breathing becomes difficult, chest tightness sets in, and fluid builds up in the lungs. At this stage, people can deteriorate very fast. Getting to medical care early makes a real difference to survival [9].

Diagnosing hantavirus in the first 72 hours is difficult. Early symptoms overlap with influenza, COVID-19, and many other common illnesses [9].

If a blood test is done before the virus or antibodies can be accurately detected, doctors will typically repeat the test 72 hours after symptoms start [20].

Diagnostic methods include:

• Blood tests (including ELISA-based antibody tests) that look for immune proteins the body makes in response to hantavirus
• Rapid immunochromatographic tests, which detect hantavirus antibodies and return results in around 10 to 15 minutes
• RT-PCR tests, which detect the virus’s genetic material directly in blood samples

There is no approved antiviral drug or vaccine for hantavirus in the United States or Europe. China and South Korea licence vaccines against the strains that cause kidney disease, but their effectiveness is uncertain and they do not protect against the lung disease form or the Andes virus [33].

Treatment focuses on keeping the body stable while it fights the infection: close monitoring in an ICU, careful fluid management, breathing support, and dialysis if the kidneys fail.

In the most severe lung disease cases, a procedure called ECMO can be life-saving. It routes blood through an external machine that adds oxygen and removes carbon dioxide, giving the lungs time to recover. When started early, the CDC reports survival rates of around 80% in cases that would otherwise be fatal [19, 20].

One antiviral drug, ribavirin, reduces deaths from the kidney disease form when given early [21]. It does not work for the lung disease form [22].

No vaccine exists for the Andes virus. Researchers have candidates in early human trials, work that gained new urgency after the 2026 cruise ship outbreak [23].

No vaccine exists for the Andes virus or the lung disease form of hantavirus. The most effective protection is avoiding contact with wild rodents and the spaces they live in.

Practical steps include sealing gaps in your home to keep rodents out, storing food in rodent-proof containers, and setting traps if needed. If you find rodent droppings, do not sweep or vacuum, as this sends viral particles into the air.

Instead, ventilate the area for at least 30 minutes, put on gloves, soak the area with a diluted bleach solution (one part bleach to nine parts water), leave it for at least five minutes, then wipe up and dispose of materials in a sealed bag.

Because the Andes virus can also spread between people, CDC recommends avoiding kissing or sexual contact with anyone who may be infected, not sharing food, drinks, or utensils, and keeping your distance from anyone who is sick [9].

Q: Can I get hantavirus from another person?

Hantavirus almost never spreads between people. The Andes virus is the only exception, and even then it requires close, prolonged contact with someone who is already symptomatic [1, 9]. Every other hantavirus, including Sin Nombre, the most common strain in the United States, spreads only through rodents.

Q: Can I get hantavirus from my pet hamster, gerbil, or rat?

Pet hamsters, gerbils, and rats are not a known source of hantavirus. The strains that infect humans are carried by wild rodents, particularly deer mice. Domestic pets are captive-bred and have no documented role in spreading the disease. (Source: CDC)

Q: Is there a vaccine for hantavirus?

There is no approved vaccine for the lung disease form of hantavirus or the Andes virus anywhere in the world. China and South Korea have licensed vaccines against the strains that cause the kidney disease form, but their effectiveness is uncertain [8, 33]. Candidates targeting the Andes virus are in early human trials but remain years from approval [24].

Q: What should I do if I find rodent droppings in my home?

Rodent droppings should never be swept or vacuumed, as this sends viral particles into the air. The area should be ventilated for at least 30 minutes before cleaning. Wearing gloves, soak the droppings in a bleach solution for five minutes, then wipe up with paper towels and seal the waste in two plastic bags. (Source: CDC)

Q: What are the early warning signs of hantavirus?

Early hantavirus symptoms closely resemble the flu: fatigue, fever, and muscle aches in the thighs, hips, back, and shoulders. About half of patients also develop headaches, dizziness, chills, nausea, and stomach pain [3]. Respiratory symptoms follow four to ten days later and can deteriorate rapidly.

Q: How long after exposure do symptoms appear?

For the lung disease form (HCPS), the incubation period is one to eight weeks. For Andes virus specifically, CDC puts it at four to 42 days. For the kidney disease form (HFRS), symptoms typically appear within one to two weeks but can take up to around six weeks [6, 9].

Q: Can I catch hantavirus on public transport, at work, or in a classroom?

Hantavirus does not spread through ordinary social contact or shared indoor air in everyday settings like offices, schools, or public transit. The risk is almost entirely tied to direct contact with infected wild rodents or their droppings. The one exception is the Andes virus, which can spread through close, prolonged contact with a sick person [1, 9].

Q: How is hantavirus treated?

There is no approved antiviral treatment for hantavirus. Care is supportive: ICU monitoring, fluid management, breathing support for the lung disease form, and dialysis for the kidney disease form. In severe cases, early use of ECMO improves survival to around 80% [19, 20]. Intravenous ribavirin reduces mortality in the kidney disease form when given early, but does not work for the lung disease form [21].

Q: What is the death rate from hantavirus?

Hantavirus death rates vary significantly by strain and syndrome. For the lung disease form in the Americas, WHO reports up to 50% [3, 4]; CDC puts US cases at around 36 to 38% [3, 18]. For the kidney disease form, the range runs from less than 1% for mild strains like Puumala to 5 to 15% for severe strains like Hantaan [5, 6].

Q: Who is most at risk of hantavirus?

People with regular exposure to wild rodent habitats face the greatest risk of hantavirus infection. This includes farmers, forestry and construction workers, military personnel, campers, and anyone cleaning rodent-infested spaces such as barns, cabins, or sheds [3, 18].

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