Health authorities across four continents scrambled Thursday to locate and monitor passengers after Dutch officials and the operator of the expedition cruise ship MV Hondius disclosed that between 29 and 40 people disembarked the vessel during a port call at the remote South Atlantic island of Saint Helena on April 24—more than two weeks before a hantavirus outbreak was confirmed aboard. The passengers, from at least 12 countries, flew home without being screened or having their contacts traced, a gap the World Health Organization and national health agencies are now racing to close.
The first known death from the outbreak occurred on April 11, when a Dutch man became ill and died aboard the ship, according to Oceanwide Expeditions. His wife, who was also infected with the Andes strain of hantavirus, was allowed to leave the vessel on April 24 when the call at Saint Helena brought the opportunity to transfer the body. She flew to Johannesburg, South Africa, on April 25 on a flight with 88 passengers. She was too sick to continue and was removed from the aircraft before takeoff, dying the same day. Her brief presence on the plane triggered a cascade of contact tracing that is now a focus of South African and European health authorities.
The ship’s first confirmed hantavirus diagnosis did not come until May 2, according to the WHO, when a British citizen evacuated from the ship and flown to South Africa tested positive. Only then did the scale of the earlier disembarkation become clear. Three people, including the ship’s doctor, were medically evacuated from the vessel near Cabo Verde on Wednesday and taken to specialized hospitals in Europe. At least five passengers have now tested positive for the virus, and a total of three have died—the Dutch man, his wife, and a German woman who died on May 2 whose body remains aboard the ship.
Among the passengers who left on April 24, cases are now surfacing across continents. Swiss authorities reported Wednesday that a man who had disembarked in Saint Helena and flown home tested positive. Singapore’s health ministry said Thursday it was monitoring two men who arrived at different times and are now isolated at the National Centre for Infectious Diseases; one has a runny nose, and the other is asymptomatic. The United Kingdom’s Health Security Agency reported that two passengers who flew home mid-voyage are self-isolating without symptoms, and a small number of their contacts are also isolating. On Saint Helena, a small number of people identified as high-risk contacts have been asked to isolate for 45 days.
The most concerning potential exposure lies outside the ship. Dutch health officials said Thursday that an Amsterdam flight attendant who boarded the same April 25 flight from Saint Helena to Johannesburg—where the fatally ill Dutch passenger was briefly present—is now showing symptoms of hantavirus and has been isolated at an Amsterdam hospital for testing. If confirmed, she would represent the first known person-to-person transmission beyond the ship itself.
The vessel, which departed from Argentina on a voyage that also called at Chile and Uruguay, is now sailing toward the Canary Islands with more than 140 passengers and crew still aboard. The WHO director-general, Tedros Adhanom Ghebreyesus, said he had been in regular contact with the ship’s captain, who reported that morale had improved significantly since the ship began moving again. But the lag between the initial deaths and the confirmation of the outbreak has drawn scrutiny. The Dutch couple’s illness was not linked to hantavirus until after the British passenger’s diagnosis in early May, by which time the April 24 disembarkation had scattered passengers worldwide.
The hantavirus variant implicated is the Andes strain, the only known hantavirus capable of human-to-human transmission. Argentina’s health ministry reported 28 deaths from hantavirus last year, with a case fatality rate of nearly 33%, up from a 15% average over the previous five years. Chile’s health ministry ruled out that the initial cases were exposed in Chile, citing incubation periods; the investigation is focusing on Argentina. Though person-to-person spread is documented, it remains rare, and the WHO assesses the general public risk as low.
National health agencies are now contacting passengers and tracing secondary contacts from the April 25 flight and subsequent travel. The episode underscores the difficulty of containing a slow-incubating pathogen aboard a vessel that crosses multiple jurisdictions, and the vulnerability exposed when contact tracing lags behind the movement of people.