Two patients with hantavirus and one suspected of infection have been removed from a cruise ship and flown to the Netherlands, the World Health Organisation says.

It comes amid reports that at least one of the four Australians among the 150 people on board the Dutch cruise ship MV Hondius at the centre of the deadly outbreak has returned home.

On Wednesday (local time), the ship departed Cape Verde bound for Spain’s Canary Islands.

Associated Press footage showed health workers in protective gear taking away three passengers. They included the ship’s British doctor, who Spain’s health ministry said had been in “serious condition” but has improved.

An air ambulance later departed.

Later the same night, a medical evacuation flight landed at Amsterdam’s airport.

Three people have died, and one body remained on the ship, the WHO said.

Of the eight cases on board, five have been confirmed by laboratory testing.

Investigations are under way to determine the source of the hantavirus outbreak. Photo: AAP

Hantavirus usually spreads by inhaling contaminated rodent droppings. It can spread human-to-human, although that is rare, according to the WHO, whose top epidemic expert said the risk to the public is low.

Health officials in Europe and Africa are trying to identify people who may have had contact with people who earlier left the ship, which departed on April 1 from South America for stops in Antarctica and several remote Atlantic islands.

One group of travellers reportedly left the Hondius during hits stop in St Helena, a tiny island in the South Atlantic, on April 23, according to one passenger who remains aboard.

“There are 23 people wandering around there, and until three days ago, no one had contacted them,” the passenger told Spanish newspaper El Pais.

“The Australian went back to Australia, the one from Taiwan to Taiwan, the Americans to all corners of North America. The Englishman to England, the Dutch to their homes … I don’t remember the rest.”

They apparently included two British men, who are self-isolating back at home after leaving the vessel in St Helena and flying home via Johannesburg in South Africa.

Britain’s Sun newspaper reports they contacted local health officials as soon as they heard of the deadly outbreak aboard the luxury cruise ship.

“UKHSA is aware of two people who have returned to the UK independently having been on board the MV Hondius,” the UK Health Security Agency said on Wednesday (local time).

“Neither of these individuals is currently reporting symptoms. They are receiving advice and support from UKHSA and have been advised to self-isolate.”

Swiss authorities have confirmed one man who returned home last month following a trip to South America with his wife before testing positive for the virus on Wednesday, which can lie dormant for up to eight weeks.

He went to a Zurich hospital for testing after the cruise operator, Oceanwide Expeditions, emailed recent passengers about the spreading virus.

He was reportedly another of the passengers to leave the ship in St Helena.

Elsewhere, Argentine officials investigating the origins of the outbreak said the government’s leading hypothesis was that a Dutch couple contracted the virus while bird-watching in the city of Ushuaia before boarding.

They said the couple visited a landfill during the tour and may have been exposed to rodents.

The officials spoke on condition of anonymity because they were not authorised to brief the media. The investigation into the outbreak of the virus – which has a mortality rate of up to 40 per cent – is continuing.

Authorities previously said Ushuaia and surrounding Tierra del Fuego province had never had confirmed hantavirus cases.

The Dutch foreign ministry said the three people who left the vessel were a 41-year-old Dutch citizen, a 56-year-old UK citizen and a 65-year-old German who would be transferred to specialised hospitals in Europe.

The WHO said on Wednesday that testing in Senegal confirmed that two of those transferred were infected with hantavirus.

-with AAP