The hantavirus outbreak aboard the M/V Hondius, which departed from Ushuaia in April 2026, was driven by Andes virus transmission between humans.
International genomic analysis confirms that while the infection originated in the Patagonian wilderness, the subsequent chain of transmission at sea caused a displacement of the Andes virus due to its capacity for human-to-human transmission.
Clinical Insights for Public Health
- Mechanism of Action: Hantaviruses typically reach people through contact with infected rodents or their excreta, but the Andes virus strain showed capacity for person-to-person transmission, which occurred during this cruise.
- Incubation Thresholds: The investigation used a maximum interval of approximately 45 days to evaluate possible exposures; however, the “Case 13” patient manifested symptoms 60 days after the departure from Ushuaia, providing proof of onboard transmission.
- Genomic Surveillance: Researchers identified a 99.9% genetic identity among viral samples, linking the cruise outbreak to historical lineages circulating in the north of Patagonia, Argentina, between 2018 and 2025.
Genomic Mapping of the Andes Virus
New evidence published in the journal Science confirms that the outbreak involved 13 cases associated with the trip, with 12 confirmed by laboratory testing and one with a probable definition, resulting in three fatalities. The investigation involved a consortium of 21 international institutions, including Argentina’s ANLIS Malbrán.
Palacios, from the Icahn School of Medicine, noted the complexity of the task. The comparison of the Andes virus characteristics in this outbreak with previous cases in the south of the country and Chile led to the identification of related viruses in cases registered between 2018 and 2025 in the north of Patagonia.
Evidence of Human-to-Human Transmission
The “Case 13” patient became the focal point for proving onboard transmission. Because this individual showed symptoms 60 days after the departure from Ushuaia—a period that exceeds the six-week incubation period considered for previous exposures—researchers concluded that the infection was acquired through close and prolonged contact with Case 10.
The investigation utilized PCR-based monitoring and genomic sequencing to track the lineage. While the initial source of the outbreak is linked to a Dutch couple who traveled through Argentina and Chile in a motorhome before embarking, their precise point of infection remains undetermined. Despite tracing their movements through border crossings like Icalma, researchers could not pinpoint the exact location of the initial exposure.
| Metric | Data Point/Observation |
|---|---|
| Total HPS Cases | 13 (12 confirmed, 1 probable) |
| Fatalities | 3 |
| Primary Vector | Andes Virus (Human-to-Human) |
| Genomic Identity | 99.9% similarity to 2018-2025 samples |
Contraindications & When to Consult a Doctor
Hantavirus pulmonary syndrome is a medical emergency. Individuals who have visited known endemic areas in Patagonia or have been in contact with rodent-infested environments should monitor for early symptoms, including fever, muscle aches, and fatigue. If respiratory distress occurs—specifically shortness of breath or persistent coughing—immediate professional medical intervention is required.
There are no specific vaccinations for the Andes virus available for the general public. Prevention relies heavily on avoiding direct contact with wild rodents and their nesting areas. Healthcare providers should maintain a high index of suspicion for patients presenting with acute respiratory failure who have a recent history of travel to rural or wilderness areas in the southern cone of South America.
Expand Viral Surveillance to Identify Environmental Sources
The investigation highlights the persistent difficulty in identifying the exact environmental source of zoonotic outbreaks. The research team emphasized that while the genetic relationship to viruses found near Villa Meliquina in 2018 provided a connection, it did not solve the mystery of where the cruise passengers first contracted the virus.
International laboratories are collaborating to show that the region where the Andes virus is endemic needs expanded viral surveillance.
References
- World Health Organization (WHO) protocols on Hantavirus surveillance and regional pathogen monitoring.
