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Toppage > Infectious Disease > Hantavirus pulmonary syndrome > risk-assessment > Hantavirus Infection Cases on a Cruise Ship During International Voyage(Second / Final Report)

Hantavirus Infection Cases on a Cruise Ship During International Voyage(Second / Final Report)

This document contains information based on official documents released by domestic and international health organizations and research institutions. Accordingly, information disclosed through press conferences or similar public briefings is not included. Information may have largely evolved since the time of publication, as investigations by domestic and international health agencies and researchers are ongoing. Readers are advised to verify the most recent official information.


Japan Institute for Health Security

July 3, 2026

About Hantavirus

Hantavirus is a collective term for viruses belonging to the genus Orthohantavirus, family Hantaviridae. Hantaviruses present in the Eurasian continent are known to cause hemorrhagic fever with renal syndrome (HFRS), whereas hantaviruses present in Americas are known to cause hantavirus pulmonary syndrome (HPS). HFRS cases associated with laboratory rats were reported in Japan during the 1970s and 1980s, but no domestic cases have been reported since 1999, when the Japan's Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (Infectious Diseases Control Law) was enacted. No cases of HPS have been reported in Japan to date.

Hantaviruses naturally infect rodents, and human infection primarily occurs through direct contact with droppings, or saliva of infected rodents, inhalation of contaminated aerosolized particles, or exposure to environments contaminated with feces. In general, hantaviruses are not transmitted from person to person. Exceptionally, limited instances of human-to-human transmission involving specific hantavirus species, Andes virus, have been reported in Argentina and Chile. However, these cases were reported to have involved transmission through droplets or direct contact resulting from close and prolonged exposure, and transmission was successfully prevented through appropriate isolation and contact management.

The Current Event

On 2 May 2026, an outbreak of hantavirus infection associated with a cruise ship MV Hondius was reported to the World Health Organization (WHO). The ship had departed Ushuaia, Argentina in April, and followed an itinerary across the South Atlantic with stops at South Georgia, Cooper Island, Tristan da Cunha, Gough Island, Saint Helena, and Ascension Island. The index case boarded the ship after participating in outdoor activities in South America. The case developed respiratory symptoms on 3 April and died on 11 April. On 24 April, his body was taken off the ship on Saint Helena, a British Overseas Territory. His partner, who disembarked at the same time, developed symptoms on 24 April and subsequently died in Johannesburg, South Africa, while returning home.

A third case developed symptoms on board on 21 April and was medically evacuated to Ascension Island, a British Overseas Territory, on 27 April. The patient's condition subsequently deteriorated, and was transferred to Johannesburg, South Africa, for further medical care. On 2 May, the United Kingdom and the Netherlands notified WHO of a cluster of severe acute respiratory illness of unknown cause associated with the ship. On the same day, hantavirus was detected in a specimen collected from the third case, confirming the diagnosis of hantavirus pulmonary syndrome (HPS). Genome sequencing confirmed Andes virus as the causative pathogen on 5 May.

Subsequently, one case was identified among passengers who had disembarked on Saint Helena, and two further cases were identified among passengers who had developed symptoms on board and later disembarked in Cabo Verde.

Upon the ship’s arrival in Tenerife, Canary Islands, on 10 May, there were 147 persons on board, comprising 83 passengers (including one Japanese national), 60 crew members, and four healthcare workers who had embarked in Cabo Verde. A total of 120 persons, excluding 25 crew members and two healthcare workers, disembarked in Tenerife.

The ship subsequently sailed to the Netherlands, where onboard disinfection was carried out. Following completion of the decontamination procedures, the ship was authorized by the Government of the Netherlands to resume operations and resumed its voyages on 30 May.

All passengers and crew members, other than the confirmed cases, were classified as high-risk contacts and were monitored for 42–45 days after disembarkation. In addition, passengers, flight crew, airport personnel, healthcare workers, and other individuals who may have had exposure to subsequently confirmed cases after disembarkation were placed under health monitoring according to their level of exposure. In total, 317 high-risk contacts and 336 low-risk contacts were identified. Following the completion of quarantine and health monitoring for all identified contacts, WHO declared the containment of the outbreak on 2 July. The Japanese national who had been on board was transferred from Tenerife to the United Kingdom and completed the monitoring period on 22 June.

In total, 13 cases of HPS, including 12 confirmed cases and one probable case, were reported, of whom three died (case fatality ratio: 23%). The probable case was the index case, who died on board before laboratory testing could be performed. All cases occurred are among people who travelled on board the cruise ship. The last case was identified on 22 May in a passenger under follow-up in Spain after disembarkation, who tested positive while remaining asymptomatic. The median age of the cases was 65 years (interquartile range: 56–70). Nine of the reported cases were male, and four were female.

Epidemiological investigations remain underway to determine the source of infection and the route of transmission. No evidence of rodent infestation has been identified on board the ship. In addition, viral genome sequences obtained from the confirmed cases showed a high degree of similarity. The available information suggests that the index case likely acquired the infection in South America, with subsequent human-to-human transmission occurring aboard the ship.

HPS caused by Andes virus is reported annually in South America. Although the numbers of reported cases and deaths in Argentina in 2026 have exceeded those observed in previous years, no large outbreaks attributable to sustained person-to-person transmission, other than the present event, have been reported. Reported cases continue to be confined to the four previously recognized endemic regions of the country, namely northwestern, northeastern, central, and southern Argentina.

Risk assessment and response

  • This event involved person-to-person transmission of Andes virus aboard a cruise ship, originating from the index case, who was presumed to have acquired the infection in South America. All confirmed cases are among individuals who travelled onboard the ship. Following the completion of follow up for all identified contacts, WHO confirmed outbreak containment. Therefore, no further related transmission is expected.
  • In Argentina and Chile, where Andes virus is endemic, sporadic cases of hantavirus infection acquired through rodent exposure continue to be reported every year. Although the numbers of reported cases and deaths in Argentina in 2026 have exceeded those reported in recent years, there has been no substantial change in the geographic distribution of cases. Furthermore, the epidemiological situation of HPS across the Americas, excluding Argentina, remains broadly consistent with previous years. Accordingly, the likelihood of imported cases from the Americas being identified in Japan is considered to be very low.
  • Each species of hantavirus associated with a specific rodent reservoir species. Therefore, even if a hantavirus is introduced into an area where its natural reservoir host is absent, sustained transmission in the natural environment is unlikely to be established. In the Americas, deer mice in North America and long-tailed pygmy rice rat in South America are recognized as reservoir hosts, but these rodent species are not known to inhabit Japan. The likelihood of infection in Japan with hantavirus endemic to the Americas, including Andes virus, is considered to be extremely low.
  • The reservoir hosts of hantaviruses that cause HPS, including Andes virus, which was responsible for this event, are rodent populations in the Americas. Travelers to affected areas are advised to avoid contact with rodents, their body fluids, carcasses, and droppings, as well as activities that may result in exposure to environments contaminated with rodent droppings. Where such exposure cannot be avoided, the use of gloves and masks is recommended to avoid direct contact.

Andes virus is the only hantavirus known to cause human-to-human transmission. However, unlike common respiratory pathogens, transmission is considered to occur only through prolonged and close contact with an infected person, and the risk of community transmission is considered to be low. Household members of a case should avoid sharing eating utensils, drinking vessels, or cigarettes, and should avoid kissing or sexual contact.

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