Can Andes virus spread from person to person?: Yes. Andes virus is the only hantavirus with documented person-to-person transmission, first established in the 1996 El Bolsón cluster in Patagonia where medical staff treating patients became infected.
What is Andes virus and where does it come from?: Andes virus is a hantavirus endemic to Patagonia and the Andean region of Argentina and Chile. Its reservoir is the long-tailed pygmy rice rat, and it causes HCPS with a case-fatality rate of roughly 30-40%.
How did Andes virus get onto the MV Hondius cruise ship?: The most likely exposure was pre-boarding in Ushuaia, the ship's departure port in Argentine Tierra del Fuego, where the virus circulates in the local rodent population. The HCPS incubation timeline supports pre-boarding exposure rather than at-sea transmission.Source: CIDRAP
How deadly is Andes virus compared to other hantaviruses?: Andes virus has a case-fatality rate of roughly 30-40% in confirmed cases, similar to Sin Nombre virus. What distinguishes it is person-to-person transmission capability, not higher fatality.

Background

Andes virus (ANDV) is a New World hantavirus and the only hantavirus with documented person-to-person transmission. It is endemic to the Andean and Patagonian regions of Argentina and Chile, where its reservoir is the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). Andes virus causes HCPS (hantavirus cardiopulmonary syndrome) with a case-fatality rate of approximately 30-40% in laboratory-confirmed cases. Person-to-person transmission was first documented in the 1996 El Bolsón cluster in Patagonia, where secondary cases included medical staff treating index patients without full protective equipment. All other hantaviruses, including Sin Nombre (the primary US agent), are believed to spread only from rodents to humans. Andes virus belongs to the genus Orthohantavirus.

Andes virus was confirmed in a Swiss passenger who disembarked the MV Hondius following an Antarctic expedition departing from Ushuaia, in Argentine Tierra del Fuego. The confirmation was reported by CIDRAP on 7 May 2026, raising the cluster to 8 cases, 3 deaths, with 1 critically ill passenger evacuated to South Africa. The strain identification rendered WHO Disease Outbreak News 599 (published 2 May with a rodent-only risk framing) outdated within five days. Contact tracing must now extend to close contacts of the Swiss patient rather than being limited to rodent-exposure follow-up. PAHO had flagged elevated Southern Cone hantavirus caseload in December 2025, five months before the MV Hondius sailed.

Source Material

Hantavirus — CDC Andes orthohantavirus

How the World Sees Them

WHO

The MV Hondius cluster is the first time Andes has been confirmed in a multi-country outbreak context; WHO's DON 599 risk assessment was rendered outdated by the Swiss strain identification within five days.

Switzerland

The Swiss confirmation places Andes virus on European health agency radars for the first time as an active case in a returning traveller; ECDC activated monitoring protocols previously unused for Andes.

Argentina and Chile

Andes virus is an endemic occupational and environmental hazard in Patagonia; local authorities have managed seasonal clusters for decades but a cruise-ship departure-port cluster is a novel and internationally visible scenario.

Antarctic tourism sector

The cluster implicates Ushuaia, the world's primary Antarctic departure hub, as a hantavirus-risk environment for international visitors who have no prior exposure history.