An expedition cruise became the center of a rare Andes virus outbreak, prompting international contact tracing, quarantine, testing, and genomic analysis to contain a deadly pathogen known for occasional person-to-person spread.
Rapid Communication: Andes virus outbreak linked to expedition cruise ship travel, multi-country investigation and response, April to June 2026. Image Credit: HD-Warrior80 / Shutterstock
A recent report published in the journal Eurosurveillance highlights the Andes virus outbreak aboard MV Hondius, a Dutch-flagged expedition cruise ship. As of June 18, the virus has caused 13 cases among passengers and crew, including three deaths. However, no further cases have been identified, and quarantine has been lifted for many exposed individuals, while some contacts remain under monitoring. Health officials are tracking contacts and conducting surveillance to monitor transmission and case numbers.
On May 2, 2026, health authorities of the Netherlands and the United Kingdom (UK) notified the European Centre for Disease Prevention and Control (ECDC) and World Health Organization (WHO) of a severe respiratory infection with unknown etiology among MV Hondius passengers and crew. The ship left Ushuaia on April 1, 2026, to arrive in Praia. The vessel sailed from Ushuaia to South Georgia, Cooper Island, Tristan da Cunha, Gough Island, Saint Helena, and Ascension Island, reaching Praia on May 3.
In this report, an international team of researchers describes outbreak detection, investigations, contact tracing, and efforts to improve preparedness against ANDV.
Outbreak Detection and Case Classification
Initial laboratory tests detected hantavirus, whereas subsequent testing in Switzerland and South Africa identified a member of the Orthohantavirus andesense complex as the causative agent. As of June 18, 2026, there have been one probable and 12 laboratory-confirmed cases. These include nine males and four females with a median patient age of 65 years. Three individuals eventually lost their lives (case fatality rate, 23%).
Following WHO guidance, confirmed cases included people with laboratory-confirmed ANDV infection. Probable cases included symptomatic individuals with documented exposure to probable or confirmed cases for whom laboratory testing was not possible. Those exposed to confirmed or probable cases while infectious were identified as contacts.
People who shared meals, bathrooms, or sleeping facilities, or who had direct physical contact, caregiving exposure, or prolonged close proximity for more than 15 minutes within 2 meters without wearing personal protective equipment (PPE) represent high-risk contacts. Handling personal items, clothing, body fluids, or medical waste without PPE, and sitting in the same row or within 2 rows in any direction of a case in airplanes are high-risk exposures.
Health officials considered zoonotic transmission through exposure to saliva, urine, or feces from virus-carrying rodents the most probable source of infection for the first case before embarkation. Later infections were likely the result of transmission among passengers and crew aboard the ship’s confined quarters, although investigations into shared exposures and environmental contamination are ongoing. The virus circulates among long-tailed pygmy rice rats (Oligoryzomys longicaudatus) in South America.
Contact Tracing and Population Risk Assessment
On May 6, 2026, the WHO and ECDC deemed unlikely onward transmission in households following exposure on the cruise. On May 9, the ECDC classified all ship passengers and crew as high-risk contacts and advised six weeks of quarantine with active follow-up, except for public health experts who joined the ship later and consistently used PPE.
Between April 13 and 15, the ship reached Tristan da Cunha. During this period, 10 local residents visited the ship, two stayed overnight, and six additional individuals embarked to reach Saint Helena. While the vessel remained at Saint Helena between April 22 and 24, 32 people disembarked, including the body of case 1, who was deceased, and case 2, the partner of case 1. The third individual identified with ANDV infection also left the ship to visit the island but reembarked later. While ashore, the second and third case individuals developed early symptoms of illness but did not seek care. Contact tracing in Saint Helena revealed 22 high-risk contacts who were quarantined. In addition, 67 low-risk contacts were monitored through passive surveillance.
On April 25, case 2 traveled to South Africa and became ill before departing for the Netherlands. Two days later, case 3 went ashore on Ascension Island and was transferred to South Africa for medical care. Case 7 fell ill on May 1 after returning to Switzerland and was diagnosed or confirmed in early May.
From May 3 to May 6, the vessel remained near the coast of Praia while the fifth and sixth case individuals, together with a person who had been exposed to case 4, were transferred for medical care. On May 6, two physicians and two specialists from the ECDC and WHO boarded the vessel to assess clinical conditions and potential public health risks. Four days later, the vessel reached Granadilla, Tenerife, carrying 147 asymptomatic individuals. Cases 9–13 repatriated within the next two days and tested ANDV-positive after repatriation or during quarantine monitoring.
The remaining crew members and medical personnel arrived in Rotterdam on May 18, and quarantine was later lifted for 61 passengers and crew members quarantined in the Netherlands after final PCR and serology tests returned negative results. Health officials identified 188 high-risk contacts linked to confirmed cases across seven countries. Most had completed or were expected to complete quarantine by late June, while one close contact was expected to finish on July 2.
Further Actions
The WHO and ECDC recommend testing whole blood, serum, or plasma samples from symptomatic contacts using PCR protocols established by the European Union Reference Laboratory for Public Health on Emerging, Rodent-borne, and Zoonotic Viral Pathogens (EURL-PH-ERZV). Genetic testing has shown near-identical viral sequences among five sequenced cases, with close resemblance to the ANDV responsible for the 2018 outbreak in Epuyén, Argentina.
These preliminary findings support a common source or closely linked transmission chain, but interpretation remains cautious pending additional sequencing and epidemiological data. Investigations are ongoing to clarify transmission routes, identify risk factors, and evaluate the effectiveness of public health measures. The findings are expected to improve understanding of ANDV infection dynamics and inform future outbreak preparedness and response.
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