Three people have died after a suspected outbreak of hantavirus on a cruise ship in the Atlantic Ocean that was traveling from Argentina to Cape Verde off the west coast of Africa.

The World Health Organization, or WHO, reported there was one confirmed case and five suspected cases on the MV Hondius, a Netherlands-registered specialist polar expedition cruise ship. With a crew of 57, 13 tour guides, and one doctor, the ship is described as having space for 170 passengers in 80 cabins.

The BBC reported around 150 passengers were on board, from a variety of countries.

"WHO is aware of and supporting a public health event involving a cruise vessel sailing in the Atlantic Ocean," the organization said in a statement. "Detailed investigations are ongoing, including further laboratory testing, and epidemiological investigations. Medical care and support are being provided to passengers and crew. Sequencing of the virus is also ongoing."

The website of the United Kingdom's National Health Service said the group of viruses known as hantavirus is normally carried by rodents, and passed by their urine or feces. Their effects on humans can range from "mild, flu-like illness to severe respiratory illness or hemorrhagic disease, with kidney involvement", and in rare cases it can be transmitted between humans.

According to an itinerary published on the website of tour company Oceanwide Expeditions, the ship has just completed a voyage lasting nearly six weeks, from Ushuaia in southern Argentina to just outside the Cape Verdean capital, Praia.

Initial reports said passengers had disembarked there, but Sky News quoted the local public health institute as saying no one had left this cruise ship, which remains outside the port, "to protect the population", but that medics had gone aboard.

A representative of South Africa's health ministry confirmed a couple from the Netherlands had died, with the 70-year-old man suddenly falling ill and dying on arrival at the British South Atlantic territory of St Helena and the 69-year-old woman being taken for treatment to South Africa, where she also died.

The third deceased person was also from the Netherlands.

Additionally, a 69-year-old British man is in intensive care in Johannesburg, with a confirmed case of the virus.

"We are closely monitoring reports of a potential hantavirus outbreak on the cruise ship Hondius and stand ready to support British nationals if needed," said a spokesperson for the UK's Foreign Office. "We are in touch with the cruise company and local authorities."