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Andes Virus: What It Is, How It Spreads, and the MV Hondius Cluster

Last updated: May 7, 2026 · 12:00 UTC

What is Andes virus?

Andes virus (ANDV) is a species of hantavirus and the most common cause of hantavirus pulmonary syndrome (HPS) — also called hantavirus cardiopulmonary syndrome (HCPS) — in South America. It was first identified in 1995 in Argentina and Chile. The virus is carried primarily by the long-tailed pygmy rice rat (Oligoryzomys longicaudatus), a rodent species found throughout Patagonia and parts of South America. In its rodent host, the virus causes a persistent, asymptomatic infection. It is transmitted to humans through inhalation of aerosolized rodent urine, droppings, or saliva, or through direct contact with contaminated material. (Wikipedia/ANDV, WHO Hantavirus fact sheet)

Why Andes virus is different from other hantaviruses

There are at least 20 hantavirus species known to cause disease in humans. Nearly all spread exclusively through rodent contact — person-to-person transmission has not been documented for any other strain. Andes virus is the single known exception. The World Health Organization confirms that human-to-human transmission of hantaviruses has been documented only with Andes virus, and when it occurs, it has been associated with close and prolonged contact — particularly among household members, intimate partners, and people providing direct medical care. WHO Director-General Dr. Tedros Adhanom Ghebreyesus stated on May 7, 2026 that this pattern appears consistent with the MV Hondius cluster. Andes virus is not transmitted through casual contact, airborne spread in the manner of influenza, or brief encounters. It is not analogous to COVID-19. (WHO, Time, May 7 2026)

Symptoms and disease progression

Andes virus infection follows three clinical phases. The prodromal phase — lasting several days — involves fever, muscle pain, headache, fatigue, nausea, vomiting, chills, and dizziness. These symptoms are non-specific and can resemble other common illnesses, which can delay diagnosis. The cardiopulmonary phase involves rapid deterioration: fluid accumulates in the lungs, oxygen levels drop, blood pressure falls, and patients can progress to cardiogenic shock and respiratory failure within hours. Approximately 60% of Andes virus infections progress to the severe cardiopulmonary form; about 40% remain mild. The recovery phase, if reached, involves resolution of pulmonary edema and can take weeks to months. The incubation period — time from exposure to symptom onset — is 1 to 8 weeks. (Wikipedia/ANDV, NBC News citing Dr. Pablo Vial, Institute of Sciences and Innovation in Medicine, Santiago)

Fatality rate

The case fatality rate for Andes virus infection is approximately 30–40% overall, according to researchers who have studied the virus in Argentina and Chile. The UK Health Security Agency cites a range of approximately 35–50% for the severe cardiopulmonary form specifically. The WHO notes that hantaviruses in the Americas carry a case fatality rate of up to 50%. There is no licensed specific antiviral treatment for Andes virus infection. Treatment is supportive — oxygen supplementation, ICU care, and management of respiratory and cardiovascular complications. Early hospital admission significantly improves outcomes. (WHO Hantavirus fact sheet, Newsweek citing UKHSA, Today.com citing Johns Hopkins / University of Michigan experts)

Where Andes virus is endemic

Andes virus is endemic in Argentina and Chile, with the highest concentration in Patagonia, Neuquén, and other rural southern regions. Argentina records approximately 100–200 hantavirus cases per year, most caused by Andes virus. The virus has also been detected in Uruguay, Bolivia, Brazil, and Paraguay. The 2018 Epuyén outbreak in southern Argentina — the largest documented Andes virus cluster involving person-to-person transmission — resulted in 34 cases and 11 deaths. That outbreak informed the WHO's response framework for the MV Hondius cluster. (Wikipedia/ANDV)

Andes virus and the MV Hondius cluster

On May 6, 2026, health authorities in Switzerland confirmed that the Andes strain was the hantavirus involved in the MV Hondius cluster — the first time Andes virus has been identified in a cruise ship outbreak. WHO confirmed on May 7 that the cluster involves 5 laboratory-confirmed Andes hantavirus infections and 3 deaths, of which one has been PCR-confirmed as caused by hantavirus. The index cases — a Dutch couple — are believed to have contracted the virus before boarding, likely during a birdwatching trip through Argentina, Chile, and Uruguay in the months prior to the April 1, 2026 departure from Ushuaia. WHO Director-General assessed the general public health risk as low. (WHO DON599, MV Hondius cluster tracker)

General public risk

WHO Director-General Dr. Tedros Adhanom Ghebreyesus stated on May 7, 2026 that the overall public health risk from the MV Hondius hantavirus cluster is low. Andes virus does not spread through casual contact, aerosols in crowded spaces, or brief encounters. It is not comparable to COVID-19 or influenza in transmission dynamics. The risk is concentrated among close, prolonged contacts of confirmed cases — particularly household members and intimate partners. People who were not aboard MV Hondius and have had no contact with confirmed cases are not at elevated risk. For official guidance, consult WHO or your national health authority.

Frequently asked questions

Can Andes virus spread on a plane?

Based on current WHO guidance, Andes virus requires close and prolonged contact to spread between people — not the kind of brief exposure that occurs during most commercial flights. WHO Director-General Dr. Tedros stated on May 7, 2026 that transmission has been associated with household members, intimate partners, and people providing direct medical care. In the MV Hondius cluster, a KLM flight attendant was hospitalized after brief contact with a confirmed case, but as of May 7 her test results were pending and WHO has not confirmed that brief flight contact is sufficient for transmission. (WHO, Flight attendant case)

Is Andes virus in the United States?

Andes virus is not endemic in the United States. The US has its own hantavirus strains — primarily Sin Nombre virus, which causes hantavirus pulmonary syndrome in the southwestern states — but these are distinct from Andes virus and do not spread person-to-person. In connection with the MV Hondius cluster, CDC confirmed that travelers in at least three US states are being monitored for possible Andes virus exposure as of May 7, 2026. Georgia and Virginia have confirmed monitoring. No confirmed Andes virus cases have been identified in the United States from this cluster. (US state monitoring status, CDC hantavirus page)

How long is the Andes virus incubation period?

The incubation period for Andes virus — the time between exposure and onset of symptoms — is 1 to 8 weeks, according to WHO and CDC. This long window is significant for the MV Hondius cluster because passengers who disembarked at various stops before the outbreak was identified may not have shown symptoms for weeks afterward. WHO arranged shipment of 2,500 diagnostic kits to five countries specifically to support testing of contacts during this extended monitoring window. (WHO)

Is there a vaccine or treatment for Andes virus?

There is no licensed vaccine and no licensed specific antiviral treatment for Andes virus infection as of 2026. Treatment is supportive — patients receive oxygen supplementation, ICU-level care, and management of respiratory and cardiovascular complications. Early hospital admission improves outcomes significantly. Ribavirin has been studied as a potential antiviral but has not been proven effective in clinical trials for hantavirus pulmonary syndrome. (WHO, Today.com citing University of Michigan experts)

Could Andes virus become a pandemic?

No. WHO officials and independent experts have explicitly stated that Andes virus is not analogous to COVID-19 and is not likely to cause a pandemic. WHO Director-General assessed the global public health risk as low on May 7, 2026. Andes virus spreads only through close, prolonged contact — not through casual contact, shared air in public spaces, or brief encounters. Dr. Maria Van Kerkhove of WHO stated: "This is not COVID, this is not influenza; it spreads very, very differently." The 2018 Epuyén outbreak in Argentina — the largest documented cluster with person-to-person transmission — resulted in 34 cases total and was contained. (Time, May 7 2026 citing WHO)

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