Open ecological, genomic and digital behavioural data resolve the 2026 MV Hondius Andes virus outbreak to the southern-Andean reservoir zone

The 2026 Andes virus (ANDV) outbreak aboard the MV Hondius cruise ship caused 11 confirmed cases and 3 deaths and raised questions about the origin of infection, with much media attention focused on a landfill in Tierra del Fuego.

To evaluate competing exposure hypotheses, the authors assembled open data on reservoir host occurrences, rodent serosurveys, and historical ANDV outbreaks, along with the index case's self-documented, publicly posted citizen-science digital record of movements.

Historical outbreaks associated with human-to-human transmission were concentrated within a restricted region spanning southern Chile and adjacent western Argentina. This region coincided with the distribution of the principal reservoir host, Oligoryzomys longicaudatus, and with areas identified as elevated risk by multiple ecological and genetic models. The index case was documented within this transmission focus shortly before the putative exposure period.

Together, the open data approach rapidly located the initial exposure within the established ANDV transmission focus and developed scenarios to prioritize further epidemiological investigation.