Eight cases in total have been reported from the Dutch-flagged expedition vessel MV Hondius, WHO Director-General Tedros Adhanom Ghebreyesus said during a media briefing on Thursday. Five of those cases are now laboratory‑confirmed as hantavirus, and three remain suspected. The strain involved is the Andes virus, the only hantavirus known to spread between humans, though transmission requires close and prolonged contact.
The ship left Ushuaia, Argentina, on April 1 with 147 people aboard – 88 passengers and 59 crew from 23 countries. It followed a route across the South Atlantic, stopping in remote locations such as Antarctica, South Georgia, Tristan da Cunha, Saint Helena, and Ascension Island. Where the virus was first picked up is still under investigation.
The first case was a man who developed fever, headache, and mild diarrhea on April 6. He died on board on April 11. His wife, a close contact, went ashore at Saint Helena on April 24 with symptoms. She was flown to Johannesburg, South Africa, where she arrived at an emergency department on April 26 and died. Tests later confirmed she had hantavirus. A third person, a woman on the ship, developed symptoms on April 28 and died on May 2.
A critically ill passenger was evacuated from Ascension Island to South Africa on April 27 and remains in intensive care. Three other passengers with symptoms were flown from the vessel to the Netherlands for hospital treatment, with cooperation from the government of Cabo Verde. One additional case was confirmed Thursday in a man who had left the ship in Saint Helena and later tested positive in Zürich, Switzerland.
“We assess the public health risk as low,” Tedros said, describing the event as a serious incident. He cautioned that because the incubation period for Andes virus can stretch to six weeks, more cases may be reported. Health authorities in several countries, including the United Kingdom, Switzerland, and the Netherlands, are tracing contacts of passengers who disembarked before the outbreak was identified.
Hantaviruses are carried by rodents and usually infect people through contact with rodent urine, droppings, or saliva. Human-to-human spread is rare and has been documented only with Andes virus in situations involving household members, intimate partners, or caregivers. Symptoms often begin with fever and muscle aches and can progress rapidly to severe lung damage.
The WHO was first alerted on May 2, when the United Kingdom reported a cluster of severe respiratory illness on the ship. Since then, the organization has coordinated medical evacuations, deployed an expert to the vessel, and arranged the shipment of 2,500 diagnostic kits from Argentina to laboratories in five countries. Operational guidance for the safe disembarkation of passengers and crew is being prepared. The ship remains moored off the coast of Cabo Verde, and none of the people still on board are currently symptomatic.
Health officials have stressed that the situation does not resemble the early days of COVID-19. Hantavirus is not airborne, is far less contagious, and is unlikely to cause a pandemic. However, the international response has been swift, involving governments in Europe, Africa, and South America.
The outbreak has drawn attention to the remote destinations visited by the vessel and the possibility that passengers had contact with local wildlife. Investigators are trying to determine when and where exposure occurred.