What is hantavirus and how does it spread? A primer for the public
Hantaviruses are a family of RNA viruses spread to humans through the urine, droppings and saliva of infected rodents. The family causes two main illness patterns: haemorrhagic fever with renal syndrome (HFRS), seen across Europe, Asia and the Middle East, and hantavirus pulmonary syndrome (HPS), which is concentrated in the Americas.
The viruses are considered to have very limited person-to-person transmission. Long-running surveillance data published by the US Centers for Disease Control and Prevention and by the European Centre for Disease Prevention and Control records almost no documented person-to-person spread among European strains.
Most cases arise when virus-containing particles from rodent waste are stirred into the air and inhaled. Enclosed, poorly ventilated barns, basements and disused buildings are documented high-risk environments. In US farming, mask use during seasonal cleaning has long been recommended public-health practice.
Symptoms typically appear between one and eight weeks after exposure. The first phase looks flu-like: fever, muscle pain and headache. HFRS then progresses to low blood pressure, kidney impairment and reduced urine output. HPS is marked by rapid fluid build-up in the lungs.
Case fatality varies by strain. The Puumala strain, the most common in Europe, has a case fatality rate of roughly 0.1 to 1 per cent. The Andes strain, found in South America, has been reported with a case fatality rate of 30 to 40 per cent. Samples taken from cases on the Hondius cruise ship have been confirmed as the Andes strain.
The World Health Organization's regional office for Europe says first-line laboratory testing should use RT-PCR, with antibody serology kept for retrospective confirmation. The WHO has said the cruise operator's notification has been shared with all EU member states.
No licensed antiviral exists. Care is supportive: fluid management, oxygen, dialysis where renal function falters and, in some severe HPS cases, extracorporeal membrane oxygenation. Surveillance data suggest five to ten per cent of HFRS cases require short-term dialysis.
Specialists emphasise that local outbreaks are driven by structural factors. Periods of high rodent density, often after challenging winters, tend to precede case clusters. The ECDC's annual report identifies Germany, Finland and Slovakia as priority surveillance regions in Europe.
Key rodent-control recommendations include storing grain in sealed containers, keeping homes well ventilated, sealing roof and wall cracks, and airing out long-closed spaces for at least 30 minutes before cleaning. In higher-risk zones, an N95 mask is the recommended precaution.
A candidate vaccine is in development; a phase-two trial funded by the US Defense Advanced Research Projects Agency began in 2025. Manufacturer Vir Biotechnology has said it expects to publish data by year-end. For now, national health authorities point to personal precautions and rodent control as the main public-health tools.