What is Hantavirus?

Hantaviruses are a family of rodent-borne viruses that cause serious and sometimes fatal disease in humans. This page covers what hantavirus is, how it spreads, the strains involved in the 2026 MV Hondius outbreak, and what makes the Andes virus distinct.

What is a hantavirus?

Hantaviruses are a genus of single-stranded RNA viruses belonging to the family Hantaviridae. They are primarily carried by rodents and transmitted to humans through aerosolized particles of rodent urine, droppings, or saliva. Different strains exist in different parts of the world, with distinct host species and disease patterns.

Each hantavirus strain typically has one primary rodent host species. Humans become infected when they breathe air contaminated with virus particles — for instance, while sweeping a barn, cleaning a cabin, or working in a field where rodents have been active. The disease they cause is rare but often serious.

How does hantavirus spread?

From rodents to humans

The primary route of transmission is aerosol inhalation: virus particles become airborne when contaminated rodent waste is disturbed. People can also be infected through direct contact with rodents (bites are rare but documented), or by touching surfaces contaminated with rodent excreta and then touching their face.

Between humans

Most hantaviruses do not spread from person to person. The Andes virus is the only known exception — limited human-to-human transmission has been documented, primarily in family clusters and healthcare settings with close, sustained contact in confined spaces. Even for the Andes virus, sustained community transmission has not been observed, and the risk to casual contacts is considered very low.

Symptoms of hantavirus infection

Hantavirus infection typically progresses in two phases:

Early phase (1–8 weeks after exposure)

• Fever and chills
• Severe muscle aches, especially in the thighs, hips, back, and shoulders
• Headache
• Fatigue
• Dizziness
• Nausea, vomiting, diarrhea, or abdominal pain

Late phase (4–10 days after symptoms appear)

• Coughing
• Shortness of breath
• Rapid progression to severe respiratory distress
• Fluid filling the lungs (Hantavirus Pulmonary Syndrome, or HPS)

In some Old World strains (Hantaan, Puumala, Seoul), the disease primarily affects the kidneys rather than the lungs — this is known as Hemorrhagic Fever with Renal Syndrome (HFRS). In New World strains (Sin Nombre, Andes), the disease primarily affects the lungs (HPS).

Hantavirus strains

The hantavirus genus contains dozens of strains. The most clinically important include:

New World hantaviruses (Americas)

• Sin Nombre virus (SNV) — the dominant strain in North America, found especially in the U.S. Southwest. Carried by the deer mouse. Killed actress Betsy Arakawa (wife of Gene Hackman) in March 2025.
• Andes virus (ANDV) — found in South America, particularly Argentina and Chile. Carried by the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). This is the strain involved in the 2026 MV Hondius outbreak. Unique among hantaviruses in showing documented human-to-human transmission.

Old World hantaviruses (Europe, Asia)

• Hantaan virus — endemic in China and the Koreas. Causes severe HFRS.
• Puumala virus — endemic in Northern Europe, particularly Finland and Russia. Causes a milder form of HFRS known as nephropathia epidemica.
• Seoul virus — global distribution via rats. Generally causes mild HFRS.

The Andes virus and the MV Hondius outbreak

The 2026 MV Hondius outbreak is unusual for several reasons. Andes hantavirus is normally a remote rural disease — most cases occur among forestry workers, hikers, or rural residents in Patagonia who encounter infected rodents. An outbreak among Western tourists aboard a cruise ship traveling between continents is exceptional.

Investigators believe the initial Dutch passengers were infected during pre-cruise travel in Argentina or Chile, then carried the virus aboard. The incubation period (1–8 weeks) explains why symptoms emerged days after departure. Whether subsequent cases on the ship represent person-to-person spread or shared environmental exposure remains under investigation. Genomic sequencing published 11 May 2026 found all analyzed samples were highly similar — suggesting either a single spillover with limited person-to-person spread, or multiple passengers infected from the same source on land.

For the latest case counts and the full chronological timeline of the outbreak, see the MV Hondius timeline page or the live map.

Prevention

For most people in most parts of the world, hantavirus risk is very low. People at elevated risk include those who work or live in areas with active rodent infestations. The CDC recommends:

• Seal up holes inside and outside the home to prevent rodent entry
• Trap rodents around the home and clean up nesting areas
• When cleaning rodent-contaminated areas, ventilate the space, wear gloves and a mask, and use a disinfectant (not a broom or vacuum — these aerosolize particles)
• If hiking or camping in rodent-endemic regions, avoid sleeping on the ground near rodent burrows; do not handle live or dead rodents

No vaccine or specific treatment is currently approved for any hantavirus, though several candidates are in development.