Andes virus (ANDV) is a cause of hantavirus pulmonary syndrome (HPS) in Chile and Argentina. The virus is carried and transmitted mainly by the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). Humans can become infected by breathing in aerosols that contain rodent saliva, urine, or feces, as well as through bites and scratches. In humans, infection can lead to HPS, an illness characterized by an early phase of mild and moderate symptoms such as fever, headache, and fatigue, followed by sudden respiratory failure. The case fatality rate has been about 40% (as late as 2023). Andes virus is the only hantavirus known to spread between people, a route first identified in 1996. This transmission as of 2026 is strongly supported by the evidence. Andes virus was first identified in 1995 in Argentina and Chile; there have been some outbreaks. The most recent outbreak was identified in April 2026 onboard the Dutch cruise ship MV Hondius and is ongoing.