What is Hantavirus?

The basics

Hantaviruses are a family of RNA viruses (taxonomically Hantaviridae) carried by wild rodents — mostly mice, voles, and rats — in nearly every part of the world. Each hantavirus has co-evolved with a specific rodent host: the deer mouse carries Sin Nombre virus, the striped field mouse carries Hantaan, the bank vole carries Puumala, and so on. The rodents themselves stay healthy. Humans become incidental hosts when they breathe in dust contaminated with rodent urine, droppings, or saliva.

When a hantavirus does cross into people, it produces one of two distinct illnesses: Hantavirus pulmonary syndrome (HPS) — sudden respiratory failure caused by New World strains in the Americas — or Hemorrhagic fever with renal syndrome (HFRS) — a kidney injury syndrome caused by Old World strains in Eurasia. Both can be lethal, but they look very different clinically.

How it spreads

The standard route is inhalation. Rodent urine, droppings, and saliva contain live virus; when those dry and get stirred up — sweeping a barn, cleaning a cabin that's been sitting empty all winter, disturbing nesting material — the virus becomes airborne in fine particles and people breathe it in.

Direct contact with rodents (bites, or handling carcasses) and consumption of contaminated food are also possible but much rarer. Andes virus (ANDV), found in Argentina and Chile, is the one exception to the rodent-only rule: it can transmit between people in close contact, although even that is uncommon and requires sustained exposure.

Symptoms

Both syndromes start with one to two weeks of a flu-like illness — fever, severe muscle aches, fatigue, headache — that often delays diagnosis because it looks like so many other things.

The major strains

More than two dozen hantaviruses are known to cause human disease. These are the ones that account for almost all reported cases.

Treatment

There is no FDA- or EMA-approved antiviral for hantavirus disease. Treatment is entirely supportive: oxygen, fluid management, and — in severe HPS — mechanical ventilation or extracorporeal membrane oxygenation (ECMO) to keep patients alive while the immune system clears the virus. Early hospitalisation in an intensive-care setting is the single biggest predictor of survival. Ribavirin has shown a modest benefit for HFRS in some studies but no benefit for HPS.

Prevention

Almost every prevention guideline comes down to controlling rodent exposure. Seal entry points around homes and cabins, store food in rodent-proof containers, and clear brush and woodpiles away from buildings. When cleaning a rodent-infested space:

• Ventilate the area for 30+ minutes before entering.
• Wear gloves; consider an N95 mask in heavy infestations.
• Wet droppings and nesting material with bleach solution before removing — never sweep or vacuum dry, which aerosolises the virus.
• Double-bag waste and wash hands thoroughly afterwards.

For travelers: the practical risk is concentrated in rural cabins, barns, and long-unused buildings. Hotel rooms in cities are essentially zero-risk. If you've had a possible exposure, see the risk check.

A brief history of major outbreaks

1. 1976

   Hantaan virus isolated

   Korean virologist Ho-Wang Lee isolates the virus that causes Korean hemorrhagic fever from striped field mice near the Hantan River. The pathogen — and the entire viral family — takes its name from that river.

2. 1993

   Four Corners outbreak

   A cluster of unexplained acute respiratory failures kills 13 young, otherwise healthy adults in the southwestern United States. CDC investigators identify a novel hantavirus — later named Sin Nombre — carried by deer mice. The episode names the New World syndrome: Hantavirus pulmonary syndrome.

3. 1996

   Andes virus and the first documented human-to-human spread

   An outbreak in Epuyén and El Bolsón, Argentina, leads researchers to identify Andes virus (ANDV) and document — for the first time — hantavirus transmission between people. ANDV remains the only known hantavirus with this property.

4. 2012

   Yosemite cluster

   Ten visitors to Yosemite National Park, USA, contract Sin Nombre virus after staying in tent cabins with deer-mouse infestations. Three die. The episode prompts a US-wide review of rodent-proofing standards in public lodging.

5. 2018–2019

   Patagonia ANDV cluster

   A second documented human-to-human ANDV outbreak in Epuyén, Argentina, kills 11. Health authorities impose quarantines and mass screening — among the first modern responses to a hantavirus cluster that didn't behave like a pure zoonosis.

6. 2026

   MV Hondius cruise-ship cluster

   The current outbreak. ANDV cases emerge aboard the MV Hondius during an Atlantic Odyssey voyage from Ushuaia, Argentina. Downstream cases appear in passengers returning to Switzerland, the Netherlands, the UK, the US, South Africa, and elsewhere — the first known maritime hantavirus cluster.

Frequently asked questions