What is the Andes Strain of Hantavirus – and Can it Pass Human to Human?

What is the Andes Strain of Hantavirus – and Can it Pass Human to Human?

The Andes virus (ANDV) is a unique and high-risk member of the hantavirus family. Primarily found in South America, it is the only known hantavirus capable of person-to-person transmission, making it a significant concern for international public health.

1. What is the Andes Strain of Hantavirus?

The Andes virus (ANDV) is an orthohantavirus that serves as the primary cause of Hantavirus Cardiopulmonary Syndrome (HCPS) in Chile and Argentina.

Unlike many other hantavirus strains found in North America (such as the Sin Nombre virus), the Andes strain is characterised by its high mortality rate and its unique ability to spread between humans. It was first identified in 1995 following an outbreak in the El Bolsón region of Argentina.

2. How the Virus is Transmitted

The natural reservoir for the Andes virus is the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). Humans typically contract the virus through:

• Inhalation: Breathing in “viral mists” from aerosolised rodent urine, droppings, or saliva.

• Direct Contact: Touching contaminated surfaces and then touching the mouth, nose, or eyes.

• Rodent Bites: Though rare, a bite from an infected rice rat can transmit the virus.

• Person-to-Person: This occurs through close, prolonged contact with an infected individual, typically among family members or in healthcare settings.

3. The Significance of Human-to-Human Spread

Whilst most hantaviruses are “dead-end” infections in humans, the Andes strain is the global exception. This capability was famously documented during a 2018–2019 outbreak in Epuyén, Argentina, where a single environmental exposure led to 34 confirmed cases and 11 deaths through sustained human transmission. This makes it a unique threat for localised outbreaks and travel-related spread.

4. Common Symptoms and Early Signs

The incubation period for Andes virus typically ranges from 1 to 4 weeks, though it can extend up to 8 weeks. Symptoms usually progress in two phases:

• Early Phase (Prodromal): Fever, chills, severe muscle aches (especially in the back and thighs), headache, and fatigue.

• Cardiopulmonary Phase: Rapid progression to coughing and shortness of breath as the lungs fill with fluid, often leading to respiratory failure and shock.

5. Hantavirus Cardiopulmonary Syndrome (HCPS)

The Andes strain is a leading cause of HCPS, a severe and often fatal respiratory disease. The case fatality rate is alarmingly high, often ranging between 25% and 40%.

Because the virus causes the capillaries in the lungs to leak fluid, patients can develop life-threatening pulmonary oedema very quickly, requiring immediate intensive care.

6. Geographic Distribution and Hotspots

The virus is endemic to specific regions of South America, including:

• Argentina: Specifically the Northern, Central, and Patagonian regions.

• Chile: Primarily the southern rural and semi-rural areas.

• Uruguay and Brazil: Related strains have been identified, though the classic Andes strain is most concentrated in the Andean foothills.

7. Diagnosis and Detection

Diagnosing Andes hantavirus can be difficult because early symptoms mimic the flu. Doctors use several methods for confirmation:

• Serology: Checking for IgM and IgG antibodies specific to the virus.

• RT-PCR: Detecting the viral RNA in blood or tissue samples.

• Clinical History: Assessing whether the patient has traveled to endemic areas or had contact with rodents or known cases.

8. Current Treatment Options

There is currently no vaccine or specific antiviral treatment approved for Andes virus. Management is primarily “supportive,” focusing on:

• Intensive Care (ICU): Monitoring and supporting heart and lung function.

• Mechanical Ventilation: Helping the patient breathe during the acute respiratory phase.

• ECMO: In extreme cases, Extracorporeal Membrane Oxygenation is used to oxygenate the blood outside the body.

9. Prevention and Safety Tips

To reduce the risk of infection, especially in endemic areas, the following precautions are recommended:

• Rodent-Proofing: Seal gaps in homes and sheds to prevent rodent entry.

• Safe Cleaning: Do not sweep or vacuum rodent droppings; instead, wet the area with a bleach solution before wiping it up to prevent the virus from becoming airborne.

• Airtight Storage: Keep food and trash in sealed containers.

• Avoid Contact: If someone is known to be infected with the Andes strain, avoid close physical contact and use appropriate personal protective equipment (PPE).

10. Current Outbreaks and Global Monitoring

In May 2026, the UKHSA and WHO is monitoring an outbreak on the MV Hondius cruise ship departing from South America – and the Andes strain had been implicated. Such events highlight the importance of international surveillance.

Whilst the risk to the general global population remains low, the Andes strain’s ability to move between people ensures it remains a high priority for epidemiologists and infectious disease researchers worldwide.