Pandemic Watch
Hantavirus disease: a complete guide
Hantaviruses are a family of rodent-borne viruses that cause serious human illness across six continents. This page is a working reference: what hantavirus is, how it spreads, who is at risk, the symptoms to watch for, and what to do about it. For the live outbreak picture, visit the dashboard or outbreak map.
What is hantavirus?
"Hantavirus" is the common name for any virus in the family Hantaviridae, order Bunyavirales. These are single-stranded RNA viruses whose natural hosts are rodents and, in a smaller subset, shrews, moles, and bats. Each strain has co-evolved with one or two specific reservoir species and generally produces lifelong, asymptomatic infection in those animals. Humans are accidental hosts: when we encounter infectious rodent excreta, we can be infected, but we do not maintain the virus in nature.
Hantaviruses cause two clinically distinct syndromes in humans. In the Americas, infection typically progresses to hantavirus pulmonary syndrome (HPS), also called hantavirus cardiopulmonary syndrome (HCPS) — an acute respiratory and circulatory collapse with a case-fatality rate of roughly 35 to 40 percent. Across Europe and Asia, the dominant strains cause hemorrhagic fever with renal syndrome (HFRS) — a febrile illness that can progress to bleeding, shock, and acute kidney injury. Mortality from HFRS ranges from under 1 percent to about 15 percent depending on the strain.
The family was first recognized as a distinct pathogen during the Korean War, when more than 3,000 United Nations soldiers developed an unexplained hemorrhagic fever near the Hantaan River. The Hantaan virus itself was not isolated until 1976. The HPS picture emerged much later, in 1993, after an outbreak of fatal respiratory illness in the Four Corners region of the United States led researchers to identify Sin Nombre virus.
Symptoms and clinical course
Both syndromes start with a non-specific prodrome that looks like influenza or many other viral illnesses. After an incubation period of one to eight weeks (typically two to four), patients develop:
- Sudden onset of fever and chills
- Severe muscle aches — classically in the thighs, hips, and back
- Headache, often described as intense
- Fatigue and weakness
- Abdominal pain, nausea, vomiting, or diarrhea in some patients
This prodromal phase lasts roughly three to seven days. The transition to the syndrome-specific phase is what makes hantavirus distinct — and dangerous.
The cardiopulmonary phase (HPS)
Patients with HPS develop a cough, shortness of breath that worsens over hours rather than days, and rapidly progressive pulmonary edema. Lungs fill with protein-rich fluid; oxygen levels drop sharply. Cardiac function follows: shock, low blood pressure, and abnormal heart rhythms. Without intensive care with mechanical ventilation, and in severe cases extracorporeal membrane oxygenation (ECMO), mortality is high. The window between the first respiratory symptom and life- threatening illness can be less than 24 hours.
The renal phase (HFRS)
HFRS progresses through five characteristic phases: febrile, hypotensive, oliguric (reduced urine output), diuretic, and convalescent. Patients develop sharp drops in blood pressure, bleeding tendency (petechial rash, conjunctival hemorrhage, GI bleeding), and acute kidney injury that often requires temporary dialysis. The illness is severe but the trajectory is slower than HPS — most fatalities occur during the oliguric phase, not the initial respiratory phase.
When to seek emergency care: shortness of breath, rapid breathing, or chest tightness after a recent rodent exposure — even if it was weeks ago — is a medical emergency. Tell the clinician about the exposure: hantavirus is uncommon enough that without that history, the syndrome is easily mistaken for community-acquired pneumonia or influenza until the cardiopulmonary collapse begins.
How hantavirus is transmitted
The primary route is inhalation of aerosolized virus particles shed in rodent urine, droppings, and saliva. Disturbing a contaminated environment — sweeping out a closed cabin, cleaning a shed, demolishing a wall — kicks dried excreta into the air, where the virus can remain suspended long enough to be breathed in. This is why HPS clusters frequently involve seasonal occupants of rural cabins, agricultural workers, and pest-control technicians.
Other documented routes:
- Direct contact with infectious material via broken skin or mucous membranes — eyes, nose, mouth.
- Rodent bites, though these are rare contributors to clinical cases.
- Contaminated food. Possible in principle but not a well-documented route; rodent contamination of stored grain has been implicated in some HFRS outbreaks.
Person-to-person transmission is the rare exception, not the rule. Of the dozens of human-pathogenic hantaviruses, only Andes virus (ANDV) in southern South America has demonstrated sustained human-to- human spread. Both the 1996 El Bolsón outbreak in Argentina and the 2018-2019 Epuyén outbreak in Patagonia showed clear transmission chains among close contacts — household members, healthcare workers, and friends — sometimes with multiple generations of cases.
Hantavirus is not transmitted by mosquitoes, ticks, fleas, or other arthropods. There is no evidence of bloodborne transmission outside the Andes-virus exception. Sexual transmission has not been documented.
Hantavirus strains and global distribution
Several hantavirus strains cause significant human disease. Each is tied to a particular rodent reservoir, which determines where in the world the strain circulates.
The dominant HPS strain in North America. Outbreaks tend to follow ecological pulses — wet winters and good seed crops drive deer-mouse population booms, which raise human risk the following spring and summer. Most US cases occur in the arid Southwest and Mountain West. Full reference →
The South American HPS strain — and the only known hantavirus that transmits person-to-person. Outbreaks repeatedly show sustained chains of cases among family, healthcare workers, and acquaintances. This complicates public health response: contact tracing, isolation, and quarantine protocols apply that are unnecessary for other hantaviruses. Full reference →
The classic "Korean hemorrhagic fever" strain. China alone reports tens of thousands of HFRS cases annually, with Hantaan virus the most severe causative agent. Vaccination campaigns in South Korea and parts of China have reduced burden in some regions, though uptake outside high-risk occupations is limited. Full reference →
The mildest of the major hantaviruses — clinically known as "nephropathia epidemica" in Scandinavia. Most patients recover fully without dialysis. Despite mortality being low, PUUV is the highest-volume hantavirus in Europe: Finland alone sees more than a thousand cases per typical year and many thousands in epizootic peak years. Full reference →
Geographically restricted but clinically severe. Among the European HFRS-causing hantaviruses, DOBV produces the highest case-fatality rate. Most cases concentrate in Slovenia, Croatia, Serbia, Bulgaria, and Greece. Full reference →
Unique among hantaviruses for being effectively urban: its rat reservoirs follow human cities and ports globally. Clusters of human SEOV cases have been documented in the United Kingdom, United States, and elsewhere, often linked to pet rat ownership or rat-infested housing. Full reference →
Prevention and rodent control
Hantavirus prevention is rodent prevention. There is no vaccine generally available; behavioral controls do the work. The objectives are: don't let rodents into your space, and if they have already been there, don't aerosolize what they left behind.
Sealing rodents out
- Seal exterior gaps larger than a quarter inch with steel wool, hardware cloth, or cement — mice can squeeze through gaps the size of a pencil.
- Install door sweeps and weatherstripping; check around pipes, vents, and utility lines.
- Store food (including pet food and birdseed) in metal or thick plastic containers with tight lids.
- Remove brush, woodpiles, and debris within 100 feet of your home — outbuildings included.
- Mow grass and trim shrubs short close to the house.
Trapping
- Use snap traps with peanut butter, baited in suspected travel paths along walls.
- Avoid live-release traps — releasing infected rodents simply moves the risk.
- Wear gloves when disposing of trapped animals; double-bag and dispose with household trash.
Safe cleanup of contaminated areas
The single highest-risk activity is cleaning up after rodents. Standard recommendations from CDC and equivalent national authorities:
- Ventilate first. Open windows and doors for at least 30 minutes before entering an enclosed space that has been sealed with rodent activity. Leave the space during ventilation.
- Wear protective equipment. Rubber or plastic gloves, and at minimum an N95 respirator. For heavy contamination, a half-face elastomeric respirator with P100 cartridges and protective eyewear.
- Wet the area first. Spray droppings, dead rodents, and nests with a disinfectant — a 1:10 household bleach solution works, or commercial disinfectant per its label — and let it soak for at least five minutes before wiping. This is the critical step. Do not sweep or vacuum dry — both aerosolize the virus.
- Clean with damp paper towels. Place soiled towels and any rodent remains in a sealed plastic bag, then a second plastic bag. Dispose with household trash.
- Wash up. Wash gloves with soap and water before removing them; wash hands thoroughly after.
- For heavy infestations — long-vacant cabins, accumulated droppings, dead rodents — consider professional pest control. The risk reward of DIY cleanup gets worse the higher the contamination.
Outdoor and travel precautions
- Air out infrequently used cabins, sheds, and outbuildings for 30+ minutes before sleeping or working in them.
- Avoid camping or sleeping near rodent burrows or den sites.
- Store food in rodent-proof containers when camping; clean up crumbs and food waste promptly.
- In endemic regions, sleep on raised cots rather than the ground when practical.
Treatment and prognosis
There is no specific antiviral drug proven to alter the course of hantavirus disease in clinical trials. Ribavirin has shown modest benefit for HFRS when started very early; for HPS the evidence is negative. Treatment is supportive, and outcomes depend heavily on the timing and aggressiveness of that support.
- Oxygen and ventilation. Patients with developing HPS need high-flow oxygen early; many progress to mechanical ventilation. ECMO is used in tertiary referral centers for refractory respiratory failure.
- Hemodynamic support. Careful fluid management — too aggressive worsens pulmonary edema in HPS; too restrictive worsens shock. Vasopressors as needed.
- Renal replacement therapy. Temporary dialysis is common in HFRS during the oliguric phase. Kidney function typically recovers in survivors over weeks to months.
- Avoid corticosteroids in HPS — they do not improve outcomes and may worsen them.
Most survivors recover fully, though convalescence can be slow. Lingering fatigue, mild exertional dyspnea, and reduced exercise tolerance have been reported in HPS survivors for months after discharge. Chronic kidney disease is uncommon after HFRS but documented in a minority of severe cases.
Prognosis hinges on a single factor more than any other: how quickly the patient reaches intensive care. A patient who arrives at a tertiary center with a developing cardiopulmonary phase, intubated and on ECMO if needed, has a meaningfully better chance of survival than one whose respiratory distress is treated as community-acquired pneumonia until cardiovascular collapse forces a transfer. This is why rodent-exposure history matters at triage.
Major outbreaks in history
A non-exhaustive selection of hantavirus events that shaped the modern understanding of the disease.
- 1951–1954 — Korean War
- Roughly 3,000 United Nations soldiers near the Hantaan River developed an unexplained hemorrhagic fever with renal complications and a case-fatality rate of about 10 percent. The etiology remained a mystery for nearly 25 years, until Karl Johnson and Ho Wang Lee isolated Hantaan virus in 1976.
- 1993 — Four Corners, United States
- A cluster of acute respiratory deaths in young, otherwise healthy Navajo individuals in New Mexico, Arizona, Utah, and Colorado triggered an investigation that identified Sin Nombre virus within months. This was the first recognition of HPS as a distinct disease. Cumulative US HPS cases since have exceeded 800.
- 1996 — El Bolsón, Argentina
- The first documented chains of human-to-human hantavirus transmission, caused by Andes virus. Spread from the index cases to physicians who attended them in Buenos Aires challenged the until-then universal assumption that hantaviruses were strictly rodent-to-human.
- 2012 — Yosemite National Park, United States
- Ten visitors who stayed in tent cabins at Curry Village were diagnosed with HPS over a single summer; three died. The outbreak prompted park-wide cabin remediation and a public notification effort that reached thousands of past visitors for symptom monitoring.
- 2018–2019 — Epuyén, Argentina
- A 29-case Andes virus outbreak in northern Patagonia produced 11 deaths and multiple generations of person-to- person transmission. Provincial authorities implemented quarantine measures unprecedented for a hantavirus event.
- 2025–2026 — Cruise-ship cluster, multi-country
- A still-evolving cluster of confirmed hantavirus cases among passengers and crew of an expedition cruise that visited Ushuaia, the Falkland Islands, South Georgia, Tristan da Cunha, Saint Helena, Cabo Verde, and ultimately the Canary Islands. Andes virus from a bird-watching excursion in Tierra del Fuego is the working hypothesis. Track the live case count on the dashboard.
Frequently asked questions
Is hantavirus contagious between people?
For almost every hantavirus strain, no — humans catch the virus from rodents, not from each other. Andes virus (ANDV) circulating in Argentina, Chile, and neighboring countries is the documented exception, with sustained person-to-person transmission recorded in several outbreaks since 1996.
Is there a vaccine for hantavirus?
There is no FDA-approved or WHO-prequalified vaccine. Inactivated HFRS vaccines have been licensed and used in South Korea and China for decades, but they are not approved for use elsewhere and provide no cross-protection against the HPS-causing American strains.
What is the mortality rate of hantavirus infection?
Mortality varies dramatically by strain. Hantavirus pulmonary syndrome (HPS), caused by Sin Nombre and Andes viruses in the Americas, has a case-fatality rate of roughly 35 to 40 percent. Among the HFRS strains in Eurasia, mortality ranges from under 1 percent for Puumala virus in Northern Europe to 5 to 15 percent for Hantaan virus in Asia.
How long does the virus survive in rodent droppings?
Outside its rodent host, the virus is relatively fragile and is inactivated by sunlight, heat, and household disinfectants. Studies suggest infectivity persists for hours to a few days under typical indoor conditions. Cool, damp, undisturbed spaces extend that window, which is why undisturbed cabins and outbuildings are higher-risk environments.
Can pets get hantavirus or transmit it to humans?
Domestic cats and dogs occasionally show antibodies to hantaviruses, indicating exposure, but they do not develop clinical disease and are not considered transmission vectors. The exception is cats that hunt rodents: they can carry infectious rodent material into the home on their fur or in prey they bring inside.
How is hantavirus diagnosed?
Diagnosis combines clinical presentation, a history of plausible rodent exposure, and laboratory confirmation by reverse-transcription PCR or serology (IgM and IgG ELISA). Both tests are typically run together because PCR detects the active virus while serology confirms an immune response. Public health authorities run the testing when clinicians notify them of a suspect case.
What should I do after cleaning up rodent droppings?
Watch for hantavirus symptoms — fever, severe muscle aches, headache, and (especially) shortness of breath — for up to eight weeks after exposure. If respiratory symptoms develop, seek emergency care immediately and tell the clinician about the rodent exposure. Early supportive care is the single biggest factor in HPS survival.
Is hantavirus a bioterrorism risk?
The U.S. CDC categorizes hantaviruses as Category C bioterrorism agents — pathogens with potential for mass dissemination that are not currently engineered for weaponization. The natural reservoir is rodents; deliberate human-to-human spread would be technically difficult outside of Andes virus.
Information on this page is synthesized from the World Health Organization Hantavirus Fact Sheet, the U.S. Centers for Disease Control and Prevention Hantavirus Disease pages, the European Centre for Disease Prevention and Control surveillance atlas, and primary epidemiological literature. It is intended as a reference for the general public and is not a substitute for individual medical advice. If you have been exposed to rodents and develop symptoms, contact a healthcare professional.
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