The World Health Organization (WHO) said it is supporting investigations into a public health emergency aboard a cruise ship in the Atlantic Ocean after one laboratory‑confirmed case of hantavirus and five additional suspected infections were reported.

Of the six affected individuals, three have died and one is currently receiving intensive care in Johannesburg, South Africa, according to the WHO.

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 Ushuaia, Argentina, on March 20 with around 150 passengers on board and made stops in Antarctica and other locations on its way to Cape Verde, according to media reports.

"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," WHO said.

Hantavirus can be spread when droppings and urine from infected rodents become airborne, such as when contaminated areas are disturbed. WHO said human-to-human transmission is rare.

The illness typically begins with flu-like symptoms and can lead to severe respiratory complications, with a case fatality rate of up to 40%, according to the US Centers for Disease Control and Prevention.