Hantavirus is the common name for a family of single-stranded RNA viruses (genus Orthohantavirus) carried by wild rodents. In people, different strains cause two distinct illnesses: hantavirus pulmonary syndrome (HPS) in the Americas, and haemorrhagic fever with renal syndrome (HFRS) across Europe and Asia. Most human infections come from inhaling aerosolised particles of infected rodent urine, droppings, or saliva.

The dominant route is breathing in airborne particles when dried rodent urine, droppings, or nesting material is disturbed — for example sweeping out a cabin, barn, or vehicle that has been closed up. Less commonly, infection follows a rodent bite, contact with broken skin, or eating food contaminated by rodents. One strain — Andes virus, found in southern South America — is the only hantavirus documented to spread from person to person, and only through close, prolonged contact.

For almost every hantavirus, no. Sin Nombre virus, Puumala, Seoul, Hantaan and other common strains have not been shown to transmit from person to person. The exception is Andes virus (ANDV), where person-to-person transmission has been documented in household and healthcare settings during outbreaks in Argentina and Chile, and is the reason the 2026 MV Hondius cluster prompted active contact tracing.

Early symptoms are non-specific and feel like a bad flu: fever, severe muscle aches (especially in the thighs, hips, back and shoulders), headache, fatigue, chills, and sometimes nausea, vomiting, diarrhoea or abdominal pain. This early phase typically lasts 3–7 days. In HPS, a sudden cardiopulmonary phase then develops with cough, shortness of breath and rapidly progressing lung fluid. In HFRS, the illness progresses through fever, low blood pressure, reduced urine output, and a recovery diuretic phase.

The incubation period — the time between exposure and the first symptoms — is usually 1 to 8 weeks, with most cases falling between 2 and 4 weeks. Because it is long and variable, contact tracing for outbreaks like the MV Hondius cluster typically watches exposed people for at least 42 days after their last potential exposure.

Fatality depends on the strain. Hantavirus pulmonary syndrome caused by New World hantaviruses (Sin Nombre, Andes) has a case-fatality rate of roughly 35–40%. HFRS caused by Hantaan virus is around 5–15% fatal; Puumala virus, the cause of nephropathia epidemica in northern Europe, is much milder, with fatality under 1%. Outcomes improve significantly with early intensive-care support.

There is no vaccine licensed for general use anywhere in the world. Inactivated HFRS vaccines are used in parts of China and South Korea but are not available elsewhere. There is also no specific antiviral cure: treatment is supportive — supplemental oxygen, mechanical ventilation, careful fluid balance, and in severe HPS, extracorporeal membrane oxygenation (ECMO). Early recognition and admission to intensive care is the single biggest factor that improves survival.

Treatment is supportive. Patients with hantavirus pulmonary syndrome are typically admitted to an intensive care unit for oxygen, ventilatory support, careful intravenous fluid management, and circulatory support; in the most severe cases ECMO is used as a bridge while the lungs recover. HFRS treatment focuses on fluid and electrolyte balance and renal-replacement therapy (dialysis) when kidneys fail. Ribavirin has shown some benefit for HFRS if started very early but is not effective for HPS.

Prevention is about reducing rodent exposure: seal gaps in homes, sheds, cabins and vehicles to keep mice out; store food and pet food in sealed containers; trap rodents indoors; and never sweep or vacuum dry droppings. To clean a contaminated area, ventilate it for at least 30 minutes, then wet the area thoroughly with a 1:10 bleach solution or commercial disinfectant before wiping with a damp cloth — and wear rubber gloves and an N95-equivalent respirator. Avoid disturbing rodent nests in barns, woodpiles or rural cabins.

Hantaviruses are present on every inhabited continent. Sin Nombre virus is the dominant strain across the United States and Canada; Andes virus circulates in Argentina and Chile; Puumala virus is widespread across northern and central Europe; Hantaan and Seoul viruses are common in East Asia; and Dobrava-Belgrade virus is found in the Balkans. Each strain is closely tied to a specific rodent reservoir, so the geographic risk follows the host species' range.

Cats and dogs do not appear to develop illness from hantavirus and are not known to transmit it to humans. They can, however, bring infected wild rodents — alive or dead — into the home, which is itself a route of indirect human exposure. Disposing of any rodent a pet has caught, while wearing gloves, and sealing it in a plastic bag is a sensible precaution.

The World Health Organization, the U.S. CDC, and the European Centre for Disease Prevention and Control have each assessed the risk to the general public as low to very low. The cluster is geographically contained to one cruise ship, the Andes virus strain involved requires close prolonged contact for human-to-human transmission, and every passenger is being individually traced and monitored. People who were not aboard the MV Hondius and have not had close contact with someone who was do not need to take any specific precautions.

Seek medical care promptly if you develop fever and muscle aches within 1–8 weeks of a known or possible rodent exposure — particularly cleaning out a cabin, shed, barn, vehicle or rural property — or if you have been identified as a contact of a confirmed hantavirus case. Tell the clinician about the exposure: hantavirus is rare and the early symptoms look like flu, so the exposure history is what triggers testing and early intensive care, which is the strongest predictor of survival.