Netherlands-based Oceanwide Expeditions said in a news release it was “managing a serious medical situation” on a polar expedition ship, the MV Hondius, which was off Cape Verde, an island nation in ​the Atlantic west of Africa.

The cruise departed from Argentina about three weeks ago ​with around 150 passengers and stopped in the Antarctic and other locations on ⁠its way to Cape Verde, according to media reports.

A Dutch Foreign Ministry spokesperson confirmed that ​two Dutch passengers had died, but gave no further details.

The World Health Organisation said in an ​X post that one of the sick passengers was in intensive care in South Africa.

Sky News reported the passenger is British, citing South Africa’s Department of Health.

The WHO said it was investigating the outbreak. Lab tests have ​confirmed hantavirus in one of the six people, the agency said.

Oceanwide Expeditions said Cape Verde ​authorities had not given permission for passengers requiring medical care to disembark, and Dutch authorities were seeking to ‌organise ⁠the repatriation of two symptomatic passengers along with the body of a deceased passenger.

Hantavirus can be spread when droppings and urine of rodents become airborne, such as when people sweep out sheds where mice have been living.

WHO said the virus can be spread between people in rare ​cases.

The illness begins with ​flu-like symptoms and can ⁠lead to heart and lung failure, with around 40% of cases resulting in death, according to the US Centres for Disease Control.

There are ​no specific drugs to treat hantavirus, so treatment focuses on supportive care, ​including putting ⁠patients on ventilators in severe cases.

“WHO is facilitating coordination between member states and the ship’s operators for medical evacuation of two symptomatic passengers, as well as full public health risk assessment and ⁠support to ​the remaining passengers on board,” the WHO said.

The British ​Foreign Office and South Africa’s Department of Health did not immediately respond to requests for comment.