Andes virus is endemic across a narrow band of southern South America that follows the distribution of its rodent reservoir, the long-tailed pygmy rice-rat. The classical heartland is Andean Patagonia — Río Negro, Chubut and Neuquén provinces in Argentina, and Aysén and Los Lagos regions in Chile. Sporadic cases also occur in Buenos Aires province, in the Argentine and Paraguayan Chaco, and in southern Bolivia and Uruguay. Transmission peaks during the austral summer (December–April) when rodent populations are highest.
Person-to-person transmission
Andes virus is a unique exception to the otherwise universal rule that hantaviruses do not spread between humans. Family clusters were first documented in the 1996 El Bolsón outbreak. Roughly 12% of confirmed Andes-virus cases are now thought to result from person-to-person spread, especially among close household contacts and healthcare workers. The May 2026 Atlantic cruise outbreak — six cases, three deaths, traced to a single index passenger from Río Negro — was the largest documented person-to-person Andes-virus event in twenty years.
Symptoms and clinical course
After an incubation period of two to four weeks, Andes-virus infection presents with fever, severe muscle aches, headache and gastrointestinal symptoms. Within a few days the patient enters the cardiopulmonary phase: rapid-onset pulmonary edema, shock and severe hypoxemia. Without aggressive intensive care — including extracorporeal membrane oxygenation in the most severe cases — case-fatality reaches 35%. Survivors typically recover lung function within months but may have persistent fatigue.
Diagnosis and treatment
Diagnosis relies on IgM ELISA and RT-PCR on serum or whole blood; rapid lateral-flow tests are emerging in Argentina and Chile. There is no licensed antiviral specific to Andes virus. Treatment is supportive: early ICU admission, careful fluid management to limit pulmonary edema, vasopressors and mechanical ventilation. Ribavirin — sometimes used for HFRS-causing hantaviruses — has not shown clear benefit for Andes-virus HPS.
Frequently asked
Is Andes virus contagious between people?
Yes. Andes virus is the only hantavirus species with documented person-to-person transmission. Roughly 12% of confirmed cases result from human-to-human spread, especially in households and healthcare settings.
How deadly is Andes virus?
The case-fatality ratio is 25–35%, depending on access to intensive care. With early ICU admission and supportive ventilation, survival improves substantially.
Where can you catch Andes virus?
Endemic transmission is concentrated in Andean Patagonia (southern Argentina and Chile). Risk is highest in rural cabins, refugios and back-country shelters between October and April.
Is there an Andes-virus vaccine?
No. Several candidate DNA and mRNA vaccines are in early-phase research as of 2026, but none are licensed.