Hantavirus is a family of viruses carried by rodents that can cause severe, sometimes fatal illness in humans. The two diseases it triggers, one attacking the lungs and one attacking the kidneys, kill between 1 in 3 and 1 in 10 people who develop symptoms, depending on the strain. There is no cure, no widely available vaccine, and no way to catch it from another person in most cases. Nearly every human infection traces back to contact with wild rodents or their droppings.
How the Virus Spreads to Humans
Hantaviruses live in certain rodent species without making the animals sick. The virus sheds in their urine, droppings, and saliva, and it can survive in dried form on surfaces. The most common route of human infection is breathing in tiny particles when contaminated material gets stirred up, whether you’re sweeping out a shed, opening a cabin that’s been closed for winter, or disturbing a mouse nest in a storage area.
You can also become infected if contaminated material touches broken skin or your eyes, if you eat food a rodent has contaminated, or in rare cases if a rodent bites you. Person-to-person spread has been documented with one South American strain (Andes virus) but is not a feature of the strains found in the United States.
In North America, the deer mouse is the primary carrier. It hosts Sin Nombre virus, which causes the vast majority of U.S. cases. White-footed mice, cotton rats, and rice rats carry other strains. In Europe and Asia, different rodent species carry the hantavirus strains responsible for kidney disease. One strain, Seoul virus, is carried by common rats worldwide and has been found in the U.S. as well.
Two Distinct Diseases
Hantaviruses cause two separate syndromes depending on which strain you’re infected with and where in the world you encounter it.
Hantavirus Pulmonary Syndrome (HPS)
This is the form found in the Americas. It targets the lungs and has a fatality rate of roughly 36%. The incubation period is typically two to three weeks after exposure. The illness begins with what feels like a bad flu: fever, chills, muscle aches, headache, and sometimes nausea, vomiting, or diarrhea. This early stage lasts several days.
Then things shift rapidly. The virus infects the cells lining blood vessels in the lungs, making them leak fluid. The result is a dangerous buildup of fluid in the lungs, a cough that worsens quickly, difficulty breathing, low blood pressure, and irregular heart rhythm. This second stage can become life-threatening within hours. The speed of this transition is what makes HPS so dangerous: by the time breathing problems appear, the patient often needs intensive care.
Hemorrhagic Fever With Renal Syndrome (HFRS)
This form occurs mostly in Europe and Asia and affects the kidneys rather than the lungs. Symptoms include high fever, bleeding under the skin, low blood pressure, and kidney failure. Fatality rates vary by strain but generally range from about 1% to 15%, making it less lethal on average than HPS but still serious.
What the Virus Does Inside the Body
Hantavirus doesn’t destroy the cells it infects the way many viruses do. Instead, it changes how blood vessel walls behave. Infected cells in the lining of blood vessels become abnormally sensitive to a signaling molecule that increases permeability, essentially telling the vessel walls to open up and let fluid through. In the lungs, this means plasma floods into the air sacs where oxygen exchange happens. The combination of fluid-filled lungs and reduced blood flow creates a crisis of low oxygen and low blood pressure simultaneously. The immune system’s response, including platelet activation and inflammation, adds to the problem rather than solving it.
How It’s Diagnosed
The early symptoms of hantavirus infection, fever, muscle pain, headache, look identical to influenza, food poisoning, or dozens of other illnesses. A blood test is often the only way to confirm the diagnosis. The standard method detects antibodies your immune system produces in response to the virus. A positive result on this antibody test, combined with symptoms and a plausible exposure history (rural area, rodent contact, cleaning a dusty space), confirms the diagnosis. Genetic testing that detects the virus’s own RNA can also be used.
The challenge is that most clinicians don’t immediately think of hantavirus when someone comes in with a fever. The disease is rare enough that early cases are often misdiagnosed. If you develop flu-like symptoms within a few weeks of being around rodent droppings or nesting material, mention that exposure to your doctor. That single detail can change how quickly you get the right diagnosis.
Treatment Options Are Limited
There is no approved antiviral that reliably treats hantavirus pulmonary syndrome. Treatment in the U.S. and Europe is entirely supportive: oxygen, mechanical ventilation, and careful fluid management to keep blood pressure stable without worsening lung flooding. Patients with severe HPS sometimes require a heart-lung bypass machine to survive the worst phase of the illness.
For hemorrhagic fever with renal syndrome, one antiviral drug has shown some benefit in reducing severity if given early. However, it carries significant side effects including a type of anemia and cannot be used during pregnancy. A vaccine exists in several Asian countries, but it is not available in the U.S. or Europe.
The lack of targeted treatment is why prevention matters so much. Surviving HPS depends heavily on how quickly you get to intensive care once the lung phase begins.
How to Reduce Your Risk
Prevention comes down to one thing: minimizing contact with rodents and their droppings. This is especially important when opening buildings that have been closed, cleaning storage areas, or working in rural settings where mice are common.
The most dangerous mistake is sweeping or vacuuming rodent droppings, which launches contaminated particles into the air. Instead, the CDC recommends this approach:
- Ventilate first. Open all doors and windows for 30 minutes before you start cleaning, and leave the area during that time.
- Wet everything down. Spray droppings and urine with a disinfectant or a bleach solution (1.5 cups of household bleach per gallon of water) until thoroughly soaked. Let it sit for at least 5 minutes.
- Wipe, don’t sweep. Use paper towels to pick up the material, then dispose of them in a sealed bag.
- Wear protection. Rubber or plastic gloves at minimum. For heavy infestations, add protective goggles, disposable coveralls, and a respirator.
- Wash carefully. Wash gloved hands with soap before removing gloves, then wash bare hands again with soap and warm water.
Sealing entry points in your home, storing food in rodent-proof containers, and keeping vegetation trimmed away from building foundations all reduce the chance of rodents moving in. Snap traps are effective for small infestations. If you find signs of a large or ongoing infestation, professional pest control is worth the cost given the stakes involved.
Who Is Most at Risk
Hantavirus is rare. The U.S. typically sees only a few dozen confirmed cases per year, mostly in rural western states where deer mice are abundant. But certain activities spike your risk considerably: cleaning out a cabin, barn, or shed that has been closed up; camping in structures with visible rodent activity; handling firewood from outdoor piles; or doing agricultural work that disturbs rodent habitat.
The virus doesn’t discriminate by age or health status. Healthy adults in their 20s and 30s have died from HPS. The common thread in almost every case is a specific moment of exposure, often one the person didn’t think twice about at the time. That’s what makes awareness the most effective form of protection: knowing that a dusty, mouse-infested space is a genuine hazard changes how you approach the cleanup.