Hantavirus is a group of viruses carried by rodents that can cause severe, sometimes fatal illness in humans. The two main diseases it triggers, one attacking the lungs and the other the kidneys, kill between 30 and 50 percent of those who develop the most serious form. Infections are rare but dangerous, and most people catch the virus not from a rodent bite but simply by breathing in dust contaminated with rodent urine, droppings, or saliva.
How People Get Infected
Hantaviruses live in certain rodent species without making the animals sick. In the United States, the deer mouse is the primary carrier. In Europe and Asia, other species including field mice, brown rats, and bank voles harbor different strains. The virus is shed in rodent urine, droppings, and saliva, and it can linger in dried material on surfaces and in dust.
The most common route of infection is inhalation. When you sweep, vacuum, or disturb areas where infected rodents have nested, tiny virus-laden particles become airborne. Breathing those particles in is all it takes. Less commonly, touching contaminated surfaces and then touching your face can lead to infection, and rodent bites or scratches are a rare but possible route. Person-to-person transmission has only been documented with one South American strain.
Two Distinct Diseases
Hantavirus causes two different syndromes depending on the strain involved. In the Americas, the primary concern is hantavirus pulmonary syndrome (HPS), which targets the lungs. In Europe and Asia, the disease takes a different form called hemorrhagic fever with renal syndrome (HFRS), which primarily damages the kidneys. Some HFRS strains cause mild illness, while others are severe.
Hantavirus Pulmonary Syndrome
HPS is the more lethal of the two. It begins with flu-like symptoms: fever, muscle aches, fatigue, and sometimes headache, nausea, or abdominal pain. Because these early signs look like many other respiratory illnesses, HPS is difficult to diagnose at first. Within a few days, the disease shifts dramatically. Fluid floods the lungs, blood pressure drops, and breathing becomes increasingly difficult. Most patients reach this dangerous phase within about 24 hours of their first hospital evaluation, and many require mechanical ventilation. Without adequate treatment, most deaths occur within 24 to 48 hours of this respiratory collapse. Even in modern intensive care units, the fatality rate for HPS ranges from 30 to 50 percent.
Hemorrhagic Fever With Renal Syndrome
HFRS moves through five clinical phases: a fever stage, a period of low blood pressure, a phase where urine output drops sharply, a recovery phase where urine output surges, and a gradual convalescence that can last weeks to months. Severity depends heavily on which strain is involved. The strain common in Scandinavia and Western Europe tends to cause a milder version sometimes called nephropathia epidemica. Strains circulating in Korea, China, and the Balkans are more dangerous. A strain carried by brown rats has worldwide distribution and usually causes mild illness, though severe cases do occur.
What the Virus Does Inside the Body
Hantavirus targets the cells lining blood vessels, particularly the thin-walled capillaries in the lungs or kidneys. It infects these endothelial cells without destroying them outright. Instead, it disrupts the molecular “glue” that holds the cells together and keeps fluid inside the bloodstream. Normally, a protein called VE-cadherin forms tight junctions between endothelial cells, creating a seal. Hantavirus infection causes these junctions to loosen, making capillaries abnormally leaky.
The virus also makes infected cells hypersensitive to a natural signaling molecule (VEGF) that the body uses to regulate blood vessel permeability. In HPS patients, levels of this molecule are markedly elevated in the lungs during the acute phase. The result is massive fluid leakage into the lung tissue, which is why patients essentially drown in their own body fluids despite having structurally intact blood vessels. In HFRS, similar leakage affects the kidneys, impairing their ability to filter blood and regulate fluid balance.
Treatment Options
There is no FDA-approved antiviral drug specifically for hantavirus. Treatment is primarily supportive, meaning the medical team focuses on keeping you alive while your immune system fights the virus. For HPS, that often means intensive care with mechanical ventilation and careful fluid management. In the most severe cases, a machine that oxygenates the blood outside the body (ECMO) may be used as a last resort.
The antiviral ribavirin has shown promise in clinical trials for HFRS in China and Korea, where it reduced kidney damage and the severity of illness. The catch is that treatment needs to begin early, before the kidneys start failing, to prevent death. For HPS, ribavirin has shown effectiveness in animal models but hasn’t proven its benefit in human clinical trials. No vaccine is currently available for use in the U.S. or Europe, though some are in use in Asia.
How to Protect Yourself
Prevention centers on avoiding contact with rodent droppings and keeping rodents out of living spaces. The critical rule: never sweep or vacuum areas contaminated with rodent droppings or urine. This launches virus particles into the air, creating exactly the exposure route that causes most infections.
If you need to clean a space with signs of rodent activity, such as a cabin, shed, barn, or garage that’s been closed up, follow these steps:
- Ventilate first. Open all doors and windows for at least 30 minutes and leave the area during that time.
- Wet everything down. Spray droppings, urine stains, and nesting material with a disinfectant or a bleach solution (1.5 cups of household bleach per gallon of water). Let it soak for at least 5 minutes.
- Wipe, don’t sweep. Use paper towels to pick up the soaked material. Place it in a sealed plastic bag, then double-bag it.
- Wear gloves. Rubber or plastic gloves throughout the process. Wash gloved hands with soap or disinfectant before removing them, then wash bare hands with soap and warm water.
- Handle dead rodents carefully. Spray the carcass and surrounding area with disinfectant, let it soak, then double-bag it for disposal. Consider using insect repellent on your clothing, since rodent fleas can carry other diseases.
Longer-term prevention means sealing gaps in your home where mice can enter (they can squeeze through openings as small as a dime), storing food in sealed containers, and keeping woodpiles and debris away from the house. If you live in a rural area or spend time in cabins and outbuildings, these precautions are especially important during seasons when mice seek indoor shelter.
Who Is Most at Risk
Hantavirus infections are uncommon. In the U.S., only a few dozen cases of HPS are reported in a typical year, mostly in rural western states. But the people who do get sick tend to share certain exposure patterns: cleaning out rodent-infested buildings, living in homes with active rodent infestations, or working in agricultural or outdoor settings where contact with wild rodents is likely. Hikers and campers who sleep in shelters with rodent activity also face elevated risk. The virus doesn’t discriminate by age or health status. Previously healthy adults make up most of the severe cases.