An apparent hantavirus outbreak is killing 3 on a cruise ship, sickening at least 3 others, health officials say.

Cape Town, South Africa – A suspected hantavirus outbreak on a cruise ship in the Atlantic Ocean has killed three people, including an elderly couple, and sickened at least three others, according to health officials and the cruise operator. The ship was waiting for help on Monday near Cape Verde, an island nation off the west coast of Africa, but local officials had not yet allowed anyone to disembark, the ship said.

At least one case of hantavirus has been confirmed through laboratory tests and the investigation is ongoing, the World Health Organization said in a statement. There were five suspected cases, including one patient who was seriously ill at a South African hospital, according to the health centre, which said it was working with authorities to remove two others with symptoms from the ship.

There was a new case that may have been on the ship, in a person showing symptoms of mild flu, Dr. Ann Lindstrand, WHO chief in Cape Verde, told the Associated Press. No other details about that case were provided.

Oceanwide Expeditions, the Dutch company that operates the ship, said the other two sick people on board were crew members with respiratory symptoms and required urgent medical attention. Cape Verdean authorities were helping as they banned people from sailing, the company said.

“Local health authorities have visited the ship to check the condition of the two people with symptoms,” the company said. “They are yet to make a decision about the transfer of these people to health care facilities in Cape Verde.”

Cape Verde sent a medical team of two doctors, a nurse and a laboratory technician to the ship on three trips, Lindstrand said. He said they are in the process of being medically discharged, where the passengers will be taken from the ship by ambulance to the airport and out of Cape Verde. The Dutch Ministry of Foreign Affairs said it was also looking into evacuating some people from the ship.

WHO regional director for Europe, Dr. Hans Henri P. Kluge, in a statement on Monday, “The risk to the general public remains low. There is no need to panic or travel restrictions.”

But Cape Verde’s Ministry of Health said, for now, the ship will not be allowed to dock on the island due to public health concerns and will remain in open waters near the coast.

Hantaviruses, found worldwide, are a family of viruses that are spread primarily through contact with the urine or feces of infected rodents such as rats and mice. They got attention after the late actor Gene Hackman’s wife, Betsy Arakawa, died of a hantavirus infection New Mexico last year.

Hackman died a week later at their home of a heart attack.

How can hantaviruses kill

Hantaviruses cause two serious syndromes, according to the US Centers for Disease Control and Prevention: hantavirus pulmonary syndrome, a serious disease that affects the lungs, and hemorrhagic fever with renal syndrome, a serious disease that affects the kidneys.

Although rare, the WHO said that hantavirus infections can spread between people. There is no specific treatment or cure, but early medical care can increase the chances of survival.

“WHO is aware of and supports the public health incident involving a cruise ship in the Atlantic Ocean,” the agency said. “Detailed investigations are ongoing, including laboratory tests, and epidemiological investigations. Medical care and support are being provided to passengers and crew. Viral sequencing is also ongoing.”

South Africa’s Ministry of Health said the ship, the Dutch-flagged MV Hondius, left Argentina three weeks ago for a trip that included visits to Antarctica, the Falkland Islands and other places. It was because he finally went to the Canary Islands of Spain.

The victims

The first victim was a 70-year-old man who died on board the ship and his body was removed from the British territory of Saint Helena in the South Atlantic, the South African Department of Health said in a statement. According to Oceanwide Expeditions, he died on April 11. The cause of his death “could not be determined on board,” a company spokesperson said in a statement.

The man’s wife collapsed at the airport in South Africa while trying to take a flight to her home country in the Netherlands, the ministry said. He died at a nearby hospital. Both the man and his wife were of Dutch descent, according to Oceanwide Expeditions.

A third passenger on board died on May 2, the company said. The body of that passenger, who is from Germany, was still on board, the company said.

The South African Department of Health has identified a patient in a hospital in Johannesburg as British. It said that the person fell ill near Ascension Island, another remote island in the Atlantic, after the ship left Saint Helena, and was taken from there to South Africa.

The person currently in critical condition is so far the only confirmed case of hantavirus connected to the ship, Oceanwide Expeditions said.

There are currently 149 people on the ship, representing 23 different nationalities, as it remains off the coast of Cape Verde, according to the company. Those still on board include 88 passengers and 61 crew members, Oceanwide Expeditions said. Seventeen American passengers.

Travel blogger Jake Rosmarin was among those who remained on the ship on Monday, he said in a social media post. Rosmarin asked the public for “kindness and understanding,” in an emotional video.

“What is happening right now is real for all of us here. We are not just a story. We are not just headlines. We are people. People with families, lives, and people waiting for us at home,” said Rosmarin. “There’s a lot of uncertainty, and that’s the hardest part. What we want right now is to feel safe, to have clarity, and to come home.”

Oceanwide Expeditions said “strict safety measures” are in place on board, including isolation and hygiene protocols, as well as medical monitoring.

The WHO said it was working with local authorities and the ship’s crew to carry out a “comprehensive assessment of the public health risk” and provide support to those still on board.

Meanwhile, the National Institute for Communicable Diseases of South Africa has been conducting contact tracing in the Johannesburg region to identify whether other people have been exposed to infected passengers in South Africa.