El Bolson
Argentine Patagonian town; site of the 1996 Andes-virus cluster that established person-to-person hantavirus transmission.
Last refreshed: 7 May 2026
Why does a 1996 Patagonian cluster still define how scientists think about the MV Hondius outbreak?
Timeline for El Bolson
Mentioned in: Andes hantavirus confirmed in Swiss returnee
Pandemics and Biosecurity- What happened in El Bolsón in 1996 and why does it matter for hantavirus?
- In 1996, an Andes hantavirus cluster of 20+ cases in El Bolsón, Argentine Patagonia, was the first documented evidence that Andes virus can spread between people in close-contact settings, including to medical staff treating patients. This established the peer-reviewed baseline that distinguishes Andes from all other hantaviruses.Source: CIDRAP / peer-reviewed literature
- Where is El Bolsón and what is it known for?
- El Bolsón is a town of about 35,000 in the Río Negro province of Argentine Patagonia, known for hops cultivation, craft beer, outdoor tourism, and its position in the Andes-virus endemic zone. It gained epidemiological significance from the 1996 hantavirus cluster that established person-to-person Andes transmission.
- Is the 2026 MV Hondius cluster comparable to the El Bolsón 1996 outbreak?
- Not directly. El Bolsón involved sustained household-level and unprotected clinical contact over multiple days in a rural setting. The MV Hondius cluster involved briefer exposure in a ship environment. Virologists at Argentina's ANLIS Malbrán institute argue the exposure geometries are different, making secondary transmission less likely than in the 1996 case.Source: CIDRAP
Background
El Bolsón is a small town of approximately 35,000 people in the Río Negro province of Argentine Patagonia, located in the Andes foothills near the Chilean border. It sits at approximately 1,000 metres elevation in a fertile valley known for hops cultivation, craft beer production, and outdoor tourism. The surrounding Nothofagus Forest and river valleys are habitat for the long-tailed pygmy rice rat, the primary reservoir of Andes hantavirus in Argentine Patagonia. El Bolsón is economically dependent on agricultural tourism and artisanal production; it is not a major transit hub and does not feature prominently in Argentine public life outside the hantavirus literature.
El Bolsón is the location of the 1996 Andes hantavirus cluster that established, in peer-reviewed literature, that Andes virus can transmit between people in close-contact settings. The cluster involved at least 20 cases, including secondary transmission to medical staff who treated original patients without adequate barrier precautions, and one physician. That 1996 event is the empirical baseline every epidemiologist cites when distinguishing Andes virus from all other hantaviruses. When the MV Hondius cluster was confirmed as Andes strain, the El Bolsón precedent immediately determined the response protocol: active secondary-case surveillance rather than standard rodent-contact follow-up. Whether the ship's cabin and shared-deck environments replicate the household-level contact at El Bolsón remains the central unresolved question in the 2026 outbreak.