A virus that follows its host
Hantaviruses do not travel on their own. Each strain is locked to a specific rodent species that evolved alongside it over thousands of years. The virus lives in the rodent's kidneys, saliva and urine without causing illness. Humans become accidental hosts when they disturb contaminated material — sweeping a dusty shed, opening a cabin that has been closed for months, or clearing brush where rodents have nested. The particles become airborne and enter the lungs.
Outside a host, the virus is fragile. Sunlight breaks it down in hours. Household disinfectant kills it on contact. But in dark, still environments — under floorboards, inside wall cavities, in grain silos — viable virus can persist in dried droppings for several days.
The global map of hantavirus
The disease wears different masks depending on where you catch it. In the Western Hemisphere, hantaviruses target the respiratory system. In the Eastern Hemisphere, they go after the kidneys. The geography determines the disease.
Americas: pulmonary syndrome (HPS)
Fluid fills the lungs. Breathing fails. Fatality rates reach 50% without intensive care. The key strains are Andes virus in Argentina and Chile (carried by the pygmy rice rat), Sin Nombre in the western United States and Canada (carried by the deer mouse), and Choclo in Panama. The first recognised cluster was the 1993 Four Corners outbreak in the American Southwest, where young Navajo people died of unexplained respiratory failure.
Eurasia: renal syndrome (HFRS)
The kidneys take the hit. Blood vessels leak. Severe cases bring hemorrhaging and shock. China reports thousands of cases annually from Hantaan virus, carried by the striped field mouse. Scandinavia sees hundreds of mild infections each year from Puumala virus, hosted by the bank vole. The Balkans contend with Dobrava virus, the most lethal European strain at 5-15% fatality.
Seoul virus: the one with no borders
Every other hantavirus is confined to a region because its rodent host is confined to a region. Seoul virus broke that pattern. It is carried by the common brown rat — an animal that colonised every continent alongside human civilisation. Seoul virus cases have appeared in pet rat owners in the United Kingdom, in urban Baltimore, and in laboratory workers in Asia. It is the only hantavirus with a genuinely global footprint, though it causes milder disease than its relatives (fatality below 2%).
Why Andes virus is the exception that changed everything
In every known hantavirus except one, the transmission chain ends with the first human patient. You catch it from a rodent, you get sick, you either recover or die — but you do not pass it to anyone else. Andes virus rewrote that rule. Found exclusively in the southern cone of South America, it can move between people through sustained close contact: sharing food, sleeping in the same room, exchanging respiratory secretions during the first days of fever.
This person-to-person capability is what made the MV Hondius outbreak possible. A single infected passenger — probably exposed at a landfill near Ushuaia — carried the virus aboard a ship where 147 people ate together, slept in adjacent cabins, and shared corridors for weeks. Had the virus been any other hantavirus, there would have been one case and no cluster.
How many people get infected each year?
WHO puts the global figure at 10,000 to 100,000 annually, with most cases concentrated in China (HFRS) and the southern cone of South America (HPS). Scandinavia contributes several hundred mild Puumala cases each year. The United States records 20-40 HPS cases annually, mostly in rural areas of the Southwest. The true number is almost certainly higher — mild infections are routinely misdiagnosed as influenza, and surveillance in many endemic regions is incomplete.
Symptoms and when to seek care →