Andes virus (ANDV)
The one hantavirus that spreads between people. Sometimes.
Andes virus (ANDV) is the only hantavirus with documented human-to-human transmission. ANDV is endemic in southern South America (Argentina and Chile) and causes hantavirus pulmonary syndrome with a case fatality of 35-50%. The 2026 MV Hondius cluster is an ANDV event with passengers exposed in Argentina before boarding.
Andes virus is endemic in Argentina and Chile
Andes virus (ANDV) is endemic in southern South America. The primary ANDV rodent reservoir is the long-tailed pygmy rice rat (Oligoryzomys longicaudatus), found in Argentina and Chile. ANDV has also been detected in parts of Uruguay, Paraguay, and Bolivia. Outside South America, Andes virus is not known to circulate naturally; the ECDC notes that the long-tailed pygmy rice rat is not present in Europe (ECDC, 6 May 2026).
Andes virus typically spreads through inhaled rodent excreta
Andes virus spreads to people by the same route as other New World hantaviruses: inhalation of aerosolized particles from rodent urine, droppings, or saliva. People are most often exposed to ANDV during outdoor activity in endemic areas (hiking, camping, rural work in Argentina or Chile) or while cleaning enclosed spaces such as cabins, sheds, or barns with rodent activity. The CDC notes that contact with the rodent itself is not required for ANDV infection; disturbing dust in a contaminated space can be enough.
Andes virus is the only hantavirus that spreads between people
Andes virus is the single hantavirus with documented person-to-person transmission. The first clear ANDV human-to-human cluster was identified in 1996 in southern Argentina. A 2014 cluster, also in Argentina, established that ANDV human-to-human transmission requires close, sustained contact with a symptomatic person. ANDV secondary case reports most often involve household members, sexual partners, and healthcare workers who treated ANDV patients without personal protective equipment.
The WHO describes Andes virus person-to-person transmission as rare. WHO's Maria Van Kerkhove stated on 7 May 2026 that the MV Hondius cluster does not change that assessment. A small number of secondary cases on a ship is consistent with the established ANDV close-contact transmission pattern.
Andes virus case fatality runs 35 to 50 percent
Andes virus produces hantavirus pulmonary syndrome (HPS) like other New World hantaviruses: an early phase of fever, muscle aches, and gastrointestinal symptoms, followed about a week later by respiratory distress and shock. CSIRO (May 2026) places the ANDV case fatality rate between 35% and 50%. The CDC reports overall HPS case fatality at approximately 38% in the United States. No specific antiviral is established for ANDV, and no ANDV vaccine is licensed; care is supportive (oxygen, fluid management, intensive care).
The 2026 MV Hondius cluster fits the established Andes virus pattern
The ECDC's working hypothesis is that MV Hondius passengers were exposed to Andes virus in Argentina before boarding the MV Hondius in Ushuaia on 1 April 2026. The first MV Hondius symptom-onset was 6 April, which fits the typical 2-to-3-week ANDV incubation period after pre-boarding exposure. A small number of secondary MV Hondius cases on board, including a lab-confirmed case who later disembarked in Switzerland, are consistent with the established ANDV close-contact transmission pattern. See the outbreak page for the full MV Hondius timeline.