GENEVA/AMSTERDAM — The World Health Organization said on Tuesday that it suspects rarely seen human-to-human transmission took place between close contacts on board a luxury cruise ship hit by seven confirmed or suspected hantavirus cases.

A Dutch couple and a German national have died, while a British national was evacuated from the ship and is in intensive care in South Africa, officials said. Three more passengers suspected to be infected are still on board, one of whom has a mild fever.

The WHO said its working assumption was that the initial case of the couple, who boarded the boat in Argentina, was infected prior, possibly while bird-watching, and that human-to-human transmission may have happened on board.

The cruise ship hit by the deadly outbreak is marooned off Cape Verde — an island nation in the Atlantic Ocean off West Africa — and not allowed to put passengers ashore.

The WHO reiterated that the risk to the wider public was low as the disease typically spreads from infected rodents and only rarely passes between humans. People are usually infected by hantavirus through contact with infected rodents or their urine, their droppings or their saliva.

However, a limited spread among close contacts has been observed in some previous outbreaks with the Andes strain, which the WHO believes could be involved in this instance.

"We do believe that there may be some human-to-human transmission that's happening among the really close contacts, the husband and wife, people who have shared cabins," Maria Van Kerkhove, director of epidemic and pandemic preparedness and prevention at the WHO, told reporters in Geneva.

"Some people on the ship were couples, they were sharing rooms so that's quite intimate contact," Van Kerkhove said.

While the WHO said the ship would be headed to the Canary Islands, Spain's health ministry said it had made no decision yet on receiving it.

"Depending on the epidemiological data collected from the ship during its passage through Cape Verde, a decision will be made as to which port of call is most appropriate," the ministry said.

Agencies Via Xinhua