The World Health Organization said on Tuesday that it suspects some rare human-to-human transmission of the deadly hantavirus took place between very close contacts on board a luxury cruise ship hit by seven confirmed or suspected cases.

Human-to-human transmission is not common, and the UN health agency reiterated that the risk to the wider public was low from a disease typically spread from contact with infected rodents.

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.

Two crew members require urgent medical care, the Dutch-flagged MV Hondius ship’s operator, Oceanwide Expeditions, said. Another person on board with a suspected case has only reported a mild fever.

The Dutch foreign ministry said it was preparing the medical evacuation of three people to the Netherlands from the ship currently moored off Cabo Verde, formerly known as Cape Verde.

The island nation in the Atlantic off West Africa was meant to be its final destination but it has not allowed the vessel to put passengers ashore because of the outbreak.