A deadly hantavirus outbreak aboard an Antarctic cruise ship went undetected for weeks before health authorities confirmed the rare Andes strain was spreading among passengers, raising fears of possible human-to-human transmission.
The outbreak has been linked to the cruise liner MV Hondius, which departed from Argentina for Antarctica on April 1. Three passengers have died, while several confirmed and suspected cases have been tied to the vessel, according to a BBC report.
Hantavirus spreads by inhaling contaminated rodent droppings and can spread from a person but it is rare.
What happened on the ship?
The first death on board was reported on April 11, when a 70-year-old Dutch man died, according to the World Health Organization (WHO). His 69-year-old wife died on April 26, followed by a German woman on May 2.
Health authorities later confirmed that at least two passengers – a British man hospitalised in Johannesburg and the Dutch woman who died – were infected with the Andes virus strain, which is primarily found in Argentina and Chile and is one of the few hantavirus strains believed capable of rare human-to-human transmission, according to several reports.
The UK’s Health Security Agency said some passengers had already left the ship earlier in the journey, which travelled from Argentina across the Atlantic to Cape Verde, but had not shown symptoms.
Also Read | Hantavirus outbreak timeline: First case on April 11 to global contact tracing
What are the symptoms?
Experts believe the virus may have spread through close contact aboard the ship as well as possible exposure to infected rodents.
Passengers have since been confined to their cabins while authorities implement isolation measures, contact tracing and monitoring protocols similar to those widely used during the Covid-19 pandemic.
The Andes strain can cause Hantavirus Pulmonary Syndrome (HPS), a severe disease that begins with symptoms such as fatigue, fever, muscle aches, headaches and dizziness before progressing to breathing difficulties that may require urgent medical intervention.
The mortality rate for the strain ranges between 20% and 40%.
Investigators track spread of the virus
Investigators are still trying to determine where the passengers contracted the virus.
Because hantavirus can incubate for up to eight weeks, authorities say the infections may have occurred before departure, during excursions in Argentina and Chile, or while aboard the ship itself.
Argentine officials are tracing the movements of infected passengers through Patagonia and Ushuaia, the southern Argentine city known as the “end of the world” where the vessel docked before departure. Investigators suspect the Dutch couple may have been exposed during a bird-watching trip in Ushuaia.
“Argentina has become more tropical because of climate change, and that has brought disruptions, like dengue and yellow fever, but also new tropical plants that produce seeds for mice to proliferate,” said Argentine infectious disease specialist Hugo Pizzi, according to a BBC report.
Argentina’s health ministry reported 101 hantavirus infections since June 2025 – double the caseload recorded the previous year. Once largely limited to Patagonia, officials say 83% of recent cases are now being recorded in Argentina’s far north.
Also Read | Hantavirus update: Where are the 23 cruise passengers? How many cases confirmed?
When authorities identified hantavirus
Health officials in South Africa first began testing for hantavirus after the British passenger in intensive care tested negative for several other illnesses. Authorities confirmed a positive hantavirus result on Saturday, 21 days after the first passenger had died aboard the ship.
The following day, WHO announced it was investigating a suspected hantavirus outbreak linked to the vessel, which by then had reached waters near Cape Verde.
The British passenger’s diagnosis then prompted South African authorities to test the Dutch woman who had died after leaving the ship. Her results also came back positive on Monday.
Swiss authorities later confirmed that the passenger who had disembarked in St. Helena had also tested positive for hantavirus.
