JOHANNESBURG, South Africa  (AFP) — An outbreak of “severe acute respiratory illness” on board a cruise ship in the Atlantic has left at least two people dead, with a third in intensive care in Johannesburg, South Africa’s health ministry told AFP on Sunday.

The outbreak occurred on the MV Hondius, travelling from Ushuaia in Argentina to Cape Verde.

The patient being treated in Johannesburg tested positive for a hantavirus, a family of viruses that can cause hemorrhagic fever, South African spokesperson Foster Mohale said.

Hanaviruses are spread by rodents, in particular, through contact with their urine, droppings and saliva, according to the United States (US) Center for Disease Control and Prevention.

“WHO is aware of the cases of severe acute respiratory illness on a cruise ship sailing in the Atlantic,” the World Health Organization (WHO) told AFP in Geneva.

“Investigations and a coordinated international public health response is underway. We will share more information as it becomes available.”

A source close to the case speaking on condition of anonymity said the provisional toll was three dead, including a Dutch couple.

The first person to develop symptoms was a 70-year-old passenger. He died on board the ship and his body was currently on the island of Saint Helena, a British territory in the South Atlantic, Mohale the South African spokesman said.

His 69-year-old wife also fell ill on board and was evacuated to South Africa, where she died in a Johannesburg hospital, he said, adding that they were not yet able to confirm the victims’ nationalities.

The third case, a 69-year-old Briton, was also evacuated to Johannesburg, where he was being treated in intensive care.

Discussions were under way to decide whether two other sick passengers should be placed in isolation in hospital in Cape Verde, after which the ship would continue to Spain’s Canary Islands, the anonymous source said.

The MV Hondius is listed as a polar cruise ship on the websites of several travel agencies. It is operated by a Dutch-based tour company, Oceanwide Expeditions.

One of the cruises offers an itinerary departing from Ushuaia for Cape Verde, with stops in the islands of South Georgia and Saint Helena.

According to several online ship-tracking sites, the MV Hondius was just off the port of Praia, the capital of Cape Verde, on Sunday.

The vessel can accommodate around 170 passengers and has some 70 crew members.

Humans can catch hantaviruses from contact with infected mice or rats or their droppings, or being bitten or inhaling contaminated dust.

There are multiple types of hantaviruses in different parts of the world, with different symptoms.

AFP contacted the cruise operator Oceanwide Expeditions but has not yet had a reply.