Hantavirus refers to a group of viruses transmitted primarily by rodents with occasional transmission to humans. People can become infected by inhaling particles contaminated with urine, droppings, or saliva from infected rodents, particularly in enclosed or poorly ventilated spaces.
Hantaviruses are classified into two major groups:
Old World hantaviruses, found in Africa, Asia, and Europe. It causes hemorrhagic fever with renal syndrome (HFRS).
New World hantaviruses, which circulate in the Americas, can cause hantavirus pulmonary syndrome (HPS).
Situation in the Americas
In December 2025, PAHO issued an epidemiological alert after observing an increase in cases in endemic countries, particularly in the Southern Cone. The alert highlighted the need to strengthen surveillance, preparedness, and response efforts for this rare but potentially fatal disease in the Region of the Americas.
Transmission of hantaviruses to humans occurs from contact with contaminated urine, droppings or saliva of infected rodents. Infection may also occur, although less commonly, through rodent bites. Activities that involve contact with rodents such as cleaning enclosed or poorly ventilated spaces, farming, forestry work and sleeping in rodent-infested dwellings increase exposure risk.
To date, human-to-human transmission has been documented only for Andes virus in the Americas and remains uncommon. When it occurs, transmission between people has been associated with close and prolonged contact, particularly among household members or intimate partners, and appears most likely during the early phase of illness, when the virus is more transmissible.
During outbreaks or when cases are suspected, early identification and isolation of cases, monitoring of close contacts, and application of standard infection prevention measures are important to limit further spread.
In the Americas, hantaviruses can cause hantavirus cardiopulmonary syndrome (HCPS), a severe respiratory illness, with a case fatality rate up to 50%.
Andes virus, found in South America, is a currently known hantavirus for which limited human‑to‑human transmission among contacts has been documented.
In Europe and Asia, hantaviruses cause haemorrhagic fever with renal syndrome (HFRS).
