A suspected hantavirus outbreak on a cruise ship in the Atlantic Ocean has killed three people and left at least three others ill, the World Health Organisation says.

A 70-year-old man and his 69-year-old wife, from the Netherlands, died after falling ill, according to the South African Department of Health.

It said the man suffered fever, headache, abdominal pain and diarrhoea, and died in St Helena. The woman was taken to hospital in the Kempton Park area of South Africa after collapsing at an airport.

The department said a third person, a British tourist, was in intensive care in a Johannesburg hospital. His laboratory test results were positive for hantavirus.

The WHO said an investigation was ongoing but that at least one case of hantavirus had been confirmed.

The outbreak is aboard the MV ​Hondius, a Dutch-flagged passenger cruise ship travelling from Argentina to Cape Verde.

The vessel is run by tour company Oceanwide Expeditions. It is described as a 107.6-metre polar cruise ship, with space for 170 passengers in 80 cabins, along with 57 crew members, 13 guides and one doctor.

About 150 tourists were on board the ship at the time of the outbreak.

It hasn’t been confirmed if any were Australian.

Oceanwide Expeditions said on Monday it was investigating if hantavirus was linked to the three deaths on the cruise.

“A strain of hantavirus has been identified in one passenger who was previously medically evacuated from the vessel and is currently being treated in intensive care in Johannesburg,” it said, referring to the 69-year-old Briton.

“Hantavirus has not been confirmed in the two symptomatic individuals currently on board.”

It said it was looking into the “exact cause” of the deaths and “any possible connection”.

“We are currently establishing the full facts and working on appropriate medical care, screening and next steps,” it said.

Aboard the MV Hondius. Photo: Ocean Expeditions/Mike Louagie

Hantavirus, which is found throughout the world, is spread by contact with the urine or faeces of infected rodents such as rats and mice.

The virus gained attention after the late actor Gene Hackman’s wife, Betsy Arakawa, died from hantavirus infection in New Mexico in 2025.

The WHO said hantavirus could lead to serious respiratory illness. According to the US Centres for Disease Control and Prevention, it can cause a severe and sometimes deadly lung infection called hantavirus pulmonary syndrome.

“Detailed investigations are ongoing, including further laboratory testing, and epidemiological investigations,” the WHO said.

“Medical care and support are being provided to passengers and crew. Sequencing of the virus is also ongoing.”

The MarineTraffic global shipping website showed the cruise ship docked in Praia, the capital of Cape Verde, on Sunday local time.

-with AP and PA