THE HAGUE/GENEVA - The World Health Organization (WHO) has confirmed a second case of hantavirus infection identified on a vessel in the Atlantic Ocean, bringing the total number of confirmed cases on board to two, Dutch cruise ship operator Oceanwide Expeditions said in a statement on Monday.

The newly confirmed case was a Dutch female passenger who died on April 27, the operator said.

About 150 people remain on board following the deaths of a Dutch couple and a German national, as well as two crew members falling ill. Another confirmed hantavirus passenger, a British national, has left the vessel and is receiving intensive care in Johannesburg, South Africa, it said.

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"Two crew members on board continue to present acute respiratory symptoms, one mild and one severe. Both require urgent medical care," the statement said. "These crew members are of British and Dutch nationality. At this time, no other persons with symptoms have been identified."

Medical teams from Cabo Verde are assisting those on board, and passengers have been asked to stay in their cabins while disinfection and other control measures are carried out, said Maria Van Kerkhove, WHO's acting director for epidemic and pandemic preparedness and prevention.

WHO is also supporting epidemiological investigations to determine the source of exposure and conducting contact tracing and laboratory testing, she added. The agency has released funds from its Contingency Fund for Emergencies to support the response.

Despite the fatalities, the overall public health risk is considered low based on current information and previous outbreaks, Van Kerkhove said.

The agency is facilitating coordination between member states and the ship's operators for the medical evacuation of two symptomatic passengers, as well as full public health risk assessment and support to the remaining passengers on board.

According to earlier reports, South Africa's National Department of Health confirmed that two people have died from an acute respiratory infection on board a cruise ship known as MV Hondius in the Atlantic Ocean.

Previous reports said MV Hondius was sailing from Ushuaia in Argentina to Cape Verde when it experienced a "severe acute respiratory illness," resulting in the deaths of an elderly couple and another person receiving treatment in an intensive care unit in Johannesburg, South Africa. 

Hantaviruses are a group of viruses carried by rodents that can cause severe disease in humans. Infection typically occurs through contact with infected rodents or their urine, droppings, or saliva, while human-to-human transmission is rare.