What is Andes virus?
Andes virus (ANDV) is a species of hantavirus first identified in Argentine Patagonia in the mid-1990s. Its primary natural reservoir is the long-tailed pygmy rice rat (Oligoryzomys longicaudatus), a small rodent native to southern Argentina and Chile.
Origin and discovery
ANDV was first isolated in 1995 following a cluster of hantavirus pulmonary syndrome cases in El Bolsón, Argentina. Sequencing showed it was distinct from Sin Nombre virus (the North American HPS strain) and revealed an unusual epidemiological pattern: clusters among household and healthcare contacts that could not be explained by shared rodent exposure.
Genetic lineage
Andes virus belongs to the genus Orthohantavirus in the family Hantaviridae. Its genome is a tri-segmented, negative-sense, single-stranded RNA. Multiple closely related lineages circulate across South America (e.g. Andes Sout, Andes Cent BsAs, Andes Lechiguanas) and share the same reservoir species or close relatives.
Geographic spread
- Argentine Patagonia (Río Negro, Chubut, Neuquén, Santa Cruz)
- Southern and central Chile (Aysén, Los Lagos, Los Ríos, Araucanía, Biobío)
- Sporadic reports in northern Argentina and bordering regions
How Andes differs from other hantaviruses
- Person-to-person transmission — confirmed only with Andes virus.
- Higher rate of household clusters than Sin Nombre virus.
- Comparable case fatality to other HPS strains (~30–40%).
Why person-to-person spread matters
Most hantaviruses cannot move directly between people — exposure to infected rodent excreta is required. Andes virus is the exception. Documented transmission events involve close, prolonged contact: spouses, parents and children, and healthcare workers caring for critically ill patients. This is why Andes outbreaks (such as the MV Hondius situation in 2026) are managed with strict isolation and 42-day contact monitoring.
2026 sequencing update
On 11 May 2026, Argentina's ANLIS-Malbrán Institute published full genetic sequencing of virus isolated from MV Hondius patients. The pathogen is unambiguously the Andes strain and shows no mutations of concern in the surface glycoproteins or polymerase relative to reference Patagonian isolates — standard PCR assays, serology and supportive care protocols all remain valid. Argentina has shipped Andes virus RNA controls and ELISA plates (enough for roughly 2,500 tests) to laboratories in Spain, Senegal, South Africa, the Netherlands and the United Kingdom.
Sources
- CDC — Andes virus and hantavirus pulmonary syndrome (May 2026).
- EL PAÍS English — initial genetic analysis of the MV Hondius outbreak (11 May 2026).
- PAHO — Hantavirus situation in the Americas.
- Ministerio de Salud, Argentina / ANLIS-Malbrán — Hantavirus epidemiological bulletins (May 2026).