PRAIA — A suspected hantavirus outbreak aboard the MV Hondius cruise ship killed three people and sickened at least three others as the vessel traveled between Argentina and Cape Verde. The World Health Organization was working with national authorities to evacuate two symptomatic passengers from the ship, which was off the port of Praia, Cape Verde, on Sunday night.

At least one case of hantavirus infection had been confirmed, with one patient in intensive care at a South African hospital. A third fatality remained onboard the ship, while two crew members required urgent medical care.

Two of the people who died were a husband and wife from the Netherlands, aged 70 and 69. The husband fell ill onboard and died on the island of Saint Helena, and the wife died at a hospital in Kempton Park, South Africa. A 69-year-old British passenger who became ill on the ship was taken to a private health facility in Johannesburg, where he tested positive for hantavirus.

Local health authorities in Cape Verde assessed the two symptomatic individuals, but the ship did not have authorization from Cape Verdean authorities to disembark people requiring medical care. Dutch authorities agreed to lead a joint effort to repatriate the two symptomatic individuals and the body of the deceased to the Netherlands, with the WHO facilitating coordination between national authorities and the ship's operators.

"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 WHO said.

A spokesperson for Oceanwide Expeditions, the ship's operator, said in a statement: "The priority of Oceanwide Expeditions is to ensure that the two symptomatic individuals onboard receive adequate and expedited medical care." The spokesperson added: "We are in close contact with those directly affected and their families and are providing support where possible."

A British government spokesperson said: "We are closely monitoring reports of a potential hantavirus outbreak on the cruise ship Hondius and stand ready to support British nationals if needed. We are in touch with the cruise company and local authorities."

The MV Hondius can accommodate about 170 passengers and has 70 crew members. The MarineTraffic global shipping website identified the vessel as a Dutch-flagged passenger cruise ship and located it docked in Praia on Sunday night.

Hantavirus is usually caught through contact with urine or feces from infected rodents, and transmission between people is rare. There is no specific treatment or cure, but early medical attention can increase the chance of survival. More than one third of patients with respiratory symptoms from hantavirus pulmonary syndrome may die from the syndrome, according to the Centers for Disease Control and Prevention.