The operator of a cruise on which three people died during a suspected outbreak of hantavirus has said the cause of death is still being investigated.

The Dutch-flagged MS Hondius is currently anchored off the Cape Verde islands, off the north-west coast of Africa, after six people travelling on the Atlantic cruise fell ill in the last month.

One of the victims was a 70-year-old Dutch man who died on board on April 11. His body was taken off the vessel on the island of St Helena on April 24, accompanied by his 69-year-old wife.

The woman fell ill while travelling back to the Netherlands and died in Johannesburg on April 27.

A third passenger, a 69-year-old British man, fell ill on the same day and was airlifted to hospital in Johannesburg, where laboratory tests showed he was infected with hantavirus. He is said to be in a critical but stable condition.

A German passenger also died during the cruise and two members of the crew are being treated for acute respiratory illness. However, the operator of the tour, Oceanwide Expeditions, said none of the three people who died or the crew members had so far tested positive for hantavirus.

Spread via rodents

In a statement, the company said: “Hantavirus has not currently been confirmed in the two persons still on board who require medical care.

“Nor has it been established that the virus is connected to the three deaths associated with this voyage. The exact cause and any possible connection are being investigated.”

The World Health Organization said on Sunday that it was responding to a “public health event” involving “five additional suspected cases” of hantavirus.

Hantavirus is a rare respiratory illness spread by rodents that is usually transmitted by inhaling the dried remains of urine and faeces. Some variants can be transmitted between people, but this is less common.

The investigations will focus on whether the passengers became infected on board the ship or during a stopover on land.

The Netherlands is taking the lead in repatriating the two sick crew members, who are British and Dutch. The body of the German victim is still on board the ship, along with 148 other passengers of mostly European nationalities.

Cape Verde authorities have visited the vessel to assess the two crew members, one of whom is said to be severely ill, but they have not yet been allowed to leave the vessel.

Continue to Tenerife

Oceanwide Expeditions said it was looking at the possibility of continuing the voyage to Las Palmas or Tenerife so the passengers could disembark and receive medical attention there.

“Strict precautionary measures are in process on board, including isolation measures, hygiene protocols and medical monitoring,” the company said. “All passengers have been informed and are being supported.”

The majority of the 61 crew are from the Philippines, but there are also crew members from countries including the UK, the Netherlands and Ukraine.

The ship left Argentina on March 20 on a 46-day voyage touring Antarctica, the Falkland Islands and St Helena. Oceanwide Expeditions is a company based in Vlissingen that specialises in cruises to polar regions.