Evidence-based answers on symptoms, transmission, the 2026 cruise ship outbreak, and prevention. Last updated: May 2026 · Sources: WHO, CDC, PAHO.
Andes virus (ANDV) is a hantavirus species endemic to southern South America — primarily Chile and Argentina. Unlike most hantaviruses, it is the only known strain capable of person-to-person transmission. It causes Hantavirus Cardiopulmonary Syndrome (HCPS), a severe respiratory illness with a case fatality rate of 25–35%.
Early symptoms (days 1–5) mimic influenza: fever, fatigue, muscle aches, headache, and gastrointestinal upset. Within 4–10 days, respiratory deterioration begins — shortness of breath, non-productive cough, and fluid accumulation in the lungs. Severe cases progress to acute respiratory distress and cardiac failure. There is no specific antiviral treatment; care is supportive in an ICU.
The incubation period is typically 9–33 days, with an average of about 18 days. This long window means exposed individuals may not show symptoms for several weeks after contact.
Yes. Andes virus is unique among hantaviruses in its confirmed person-to-person transmission potential, documented in Chile and Argentina. Transmission occurs through close contact with an infected person's respiratory secretions. No other hantavirus species has demonstrated this capability. WHO and CDC recommend standard and droplet precautions for confirmed ANDV cases.
In early 2026, a cluster of Andes virus cases was linked to a cruise vessel operating in Patagonian waters. The outbreak represented a significant public health concern due to the close-contact nature of cruise ship environments and the virus's person-to-person transmission capability. WHO issued a Disease Outbreak Notice (DON 599) covering this and related cases across Chile and Argentina.
As of the most recent WHO DON report, 7 laboratory-confirmed cases have been reported, with 3 deaths — a case fatality rate consistent with historical ANDV outbreaks. Case counts are updated as WHO publishes new reports.
The primary route is inhalation of aerosolized rodent excreta (urine, feces, saliva) from infected long-tailed pygmy rice rats (Oligoryzomys longicaudatus) — the main reservoir host in southern Chile and Argentina. Bites from infected rodents and, uniquely for ANDV, close contact with infected humans also pose a transmission risk.
Individuals at elevated risk include: rural workers and campers in Patagonia (Chile/Argentina), travelers participating in outdoor activities (hiking, trekking, camping) in endemic areas, people staying in cabin accommodations with evidence of rodent infestation, and close contacts of confirmed ANDV patients (healthcare workers, household members).
There is currently no licensed vaccine or specific antiviral approved for Andes hantavirus. Treatment is supportive — including supplemental oxygen, mechanical ventilation, and hemodynamic support in a hospital ICU. Early transfer to specialized facilities significantly improves outcomes. Ribavirin has been used experimentally but evidence of efficacy is limited.
Travelers to southern Chile and Argentina should: (1) avoid contact with wild rodents and their droppings; (2) air out enclosed spaces (cabins, shelters) before entering; (3) use DEET-based repellents and gloves when cleaning areas with rodent activity; (4) seek immediate medical care if flu-like symptoms develop within 5 weeks of potential exposure; and (5) inform healthcare providers of travel history.
Diagnosis is confirmed via RT-PCR (reverse transcriptase polymerase chain reaction) detecting ANDV RNA in blood, ELISA serology detecting IgM/IgG antibodies, and immunohistochemistry on tissue samples. Point-of-care rapid tests are not yet widely available in most clinical settings.
Both cause hantavirus pulmonary syndrome, but Sin Nombre virus (SNV) — the dominant hantavirus in North America — does NOT spread from person to person. Andes virus is unique in its confirmed interpersonal transmission. SNV is carried by deer mice (Peromyscus maniculatus) in the western United States and Canada.