Multi-Country Human-to-Human Andes Virus Outbreak on a Cruise Ship: A Disaster Report on Prehospital, Health Care Facility, and Public Health System Challenges - Essential Knowledge for Frontline Clinicians.

The Andes Virus (ANDV) outbreak reported on May 2, 2026, aboard a luxury vessel departing from Ushuaia, Patagonia, Argentina, was caused by an Orthohantavirus unique in its person-to-person transmissibility in contrast to zoonotic transmission characteristic of better-known hantaviruses. Containment required coordinated international management because passengers and crew embarked and disembarked at several international ports-of-call prior to outbreak recognition, resulting in cross-border transmission potential. Among those who disembarked, several traveled on flights to various destinations. Cases subsequently manifested in multiple countries, including Tristan da Cunha, Spain, France, Switzerland, South Africa, Canada, and The Netherlands. Upon notification, international health authorities implemented containment measures, such as contact tracing, quarantine, and isolation. Uniquely, ANDV poses distinctive risks due to its immediately prodromal presymptomatic transmission potential, initial non-specific flu-like symptoms, prolonged incubation period, conceivable long-term neurologic and endocrinologic sequalae, high case fatality rates (CFRs), and possibility of international dissemination. This report describes the successful management of a multi-national outbreak associated with cruise-ship travel, a setting with unique challenges. It also examines implications and challenges for prehospital, health care facility, and public health systems for future ANDV outbreaks. The event was characterized by delayed recognition, international spread, and complex coordination across multiple jurisdictions and sectors, including medical and public health authorities, policy- and decision-makers, crisis and emergency risk-communication experts, media, logistics, transportation, and security. Rapid implementation of public health measures coupled with clinician implementation of the Identify-Isolate-Inform (3I) model, a clinical framework to detect and prevent the spread of infectious disease, at the prehospital and health care facility levels are critical actions that can contain future ANDV outbreaks.