What is the Andes virus?

The Andes virus (ANDV) is a hantavirus species endemic to southern South America, particularly Argentina, Chile, and parts of Uruguay and Bolivia. It is named after the Andes mountain range, where the long-tailed pygmy rice rat (Oligoryzomys longicaudatus) — its primary natural reservoir — is widely distributed. ANDV causes hantavirus pulmonary syndrome (HPS) with a case fatality rate of 30-40% and is unique among hantaviruses in being capable of limited person-to-person transmission, demonstrated in clusters dating back to a 1996 outbreak in El Bolsón, Argentina. The MV Hondius cluster involves the Andes virus, with the index case having traveled extensively in Argentina, Chile, and Uruguay between November 2025 and April 2026.