There was a buzz of excited anticipation among passengers and crew as the MV Hondius departed the southernmost tip of South America 39 days ago.

There was also a sense of close camaraderie, a bond between passengers who would dine together, drink together, go on thrilling adventures and chalk up new discoveries together visiting some of the remotest locations on earth.

There are, it's said, no mates like ship mates.

Then, there are those once-in-a-lifetime expeditions that promise to deliver memories to fill a photo album multiple times over.

The Atlantic Odyssey, for which passengers paid up to £25,000 for one of the cabins laid out across seven decks, was one of those trips.

Little did the passengers who began that journey realise that a camaraderie forged viewing icebergs and spotting penguins, whales, albatross and other rare wildlife would become even closer after a death on board turned the cruise ship into the epicentre of an outbreak of Hantavirus – a rare but deadly virus carried by rats.

So far three people have died. Another five, possibly six, including three Britons, are thought to have been infected by the one strain of the virus known to be capable of transmission via human-to-human contact, and which has a mortality rate of 40 per cent.

And now, as the boat prepares to dock in Tenerife having been turned away from its original destination of Cape Verde, a frantic worldwide search is on for anyone who has come into contact with passengers who've disembarked along the way. Ruhi Cenet, a father of two and a filmmaker, is one of them.

Until two weeks ago, he was a passenger on board MV Hondius and is now anxiously self-isolating at home in Istanbul.

Speaking exclusively to the Daily Mail, he recalls the moment on April 12 when the ship's captain announced the death on board of a 70-year-old Dutch man.

'He [the captain] said it was his sad duty to inform us that a passenger had passed away the night before,' says Ruhi.

'He said it was very tragic but it was due to natural causes, which we now know was wrong. He even said the doctor had said it wasn't infectious and the ship was safe.'

Ruhi recalls, too, how everyone flocked to console his widow – not knowing then that her husband had been killed by a deadly virus which she was also carrying.

'Everyone was feeling so sorry for her. They were hugging her and talking with her,' Ruhi told the Daily Mail.

'People were just trying to support her because she had lost her husband. She called us her protective angels. She was a very nice, kind person, but perhaps it was not the best thing for people to hug her and be so close to her.'

He also recalls, with increasing unease, how life on board carried on unchanged. 

'Of course, everyone was sad to hear the news, but we carried on as normal. We would sit together for meals, drink and eat together, go to the buffet. No one had any idea that this virus was circulating among the passengers.

'The group activities continued, star-gazing and exercise classes, everything went on as normal; bird photography and lectures and the daily meetings at 6pm carried on in the lounge area.

'People were always sitting close together. Looking back, not knowing this virus was on board and we were all so close to each other is quite frightening to think about.'

The Atlantic Odyssey trip prepared to reach the end of its first stage in St Helena on April 24, at which point 30 passengers from 12 countries were scheduled to disembark and fly home.

Ruhi was one of them, along with the widow of the dead man. As he disembarked he noticed she suddenly appeared unwell. 'I remember the day we got off she was struggling to walk,' he says.

She died two days later, having been flown to hospital in Johannesburg.

'An Oceanwide voyage unlike any other' is how the advertising blurb describes a trip on board MV Hondius.

How ironic those words must feel now for the 146 passengers and crew still on board today as the ship makes its final approach towards Granadilla, Tenerife, 900 nautical miles away from its original destination, where it is scheduled to dock in the early hours of tomorrow morning.

The Hondius should have disembarked its remaining passengers in Cape Verde a week ago, but the infection crisis triggered a global alarm – not least because those who initially boarded back on April 1 hailed from 28 countries.

The alert was only raised about a Hantavirus contagion on May 2 – the day of the third on board fatality, a German woman – a day before it was due to dock at Cape Verde.

Ruhi was among the 114 passengers who had boarded MV Hondius on April 1, to begin a 24-day journey from the Tierra del Fuego archipelago to St Helena.

The ship's planning included an optional second ten-day journey from St Helena to Cape Verde, crossing the equator, which was taken only by some. After leaving Tierra del Fuego, the first stop was at the sub-Antarctic wildlife oasis of South Georgia on April 5, where passengers were able to disembark.

Ironically, biosecurity measures on the Hondius are stringent, in large part due to strict protocols designed to protect the fragile ecosystem of South Georgia, where rats have been completely eradicated since 2018.

It was the following day that the Dutch man – who is now being considered as patient zero – became ill, dying on April 11.

Prior to boarding, he and his wife had travelled around Argentina and Chile in a van, enjoying bird-watching at various locations, and it is their travels that are now being probed in an attempt to discover the source of the virus.

Two days after the Dutch man's death, the boat made a stop at Tristan da Cunha, the most remote inhabited island in the world, but his body remained on board in the ship's tiny morgue until the Hondius reached St Helena on April 24, by which time his wife was also displaying signs of illness.

In the wake of the first death, Ruhi says: 'There were hand sanitisers, but people were not wearing masks and there was only one doctor who was always super-busy because people didn't feel well, but the initial thought was sea sickness.' He finds it all bewildering. 'In my opinion these ships should have laboratories on board so they can test when someone dies,' he adds. 'The captain and doctor were all completely in the dark because no one knew what the cause was.

'After the second death, it was obvious there was a virus on board, but by then it was too late. We were not kept properly informed and for 12 days there were no precautions at all.'

Ruhi worries particularly for remote communities in places such as Tristan da Cunha, which was his own trip highlight.

'We were there from April 13 to 14 and went ashore, and people could well have [unknowingly] had the virus and spread it among people living on the island. We may have put them in danger and that is one of my biggest regrets.'

Those worries appear well-founded. Yesterday, it emerged that a Briton who was on the island, which has fewer than 300 residents, was being treated for a suspected Hantavirus infection. He would be the third Briton infected.

For after Ruhi and others departed the cruise at St Helena, back on the ship a British man fell ill on April 27 and was evacuated from Ascension Island, home to a British military base, to South Africa, where his condition in hospital is said to have improved.

The third fatality, a German woman, died on the ship on May 2, four days after falling ill. By the end of last week, the ship's doctor, along with British expedition guide and former policeman Martin Anstee and another passenger also became ill. These three were evacuated on Wednesday to the Netherlands for treatment.

An eighth passenger is being treated in hospital in Zurich, Switzerland, after becoming unwell after leaving the vessel.

For those still on board, in the absence of the ship's only doctor, crew (who receive some medical training and for whom there appears to have been nothing but praise) turned to their passengers for help.

Retired oncologist Stephen Kornfeld, a keen ornithologist who had boarded the trip hoping to add as many new species as possible to his birding list, stepped forward when crew asked on May 1 if any passengers had a medical background and could help in the absence of a ship's physician.

'I sort of fell into the role of becoming the ship doctor,' Kornfeld said.

He has taken on a growing burden of responsibility, juggling his patients with communications with medical researchers, the World Health Organisation (WHO) and the ship's operating company.

Initially, he said, his patients 'had a lot of standard viral symptoms. A lot of fever, fatigue, flushing, some GI [gastrointestinal] issues, some shortness of breath.'

When he stepped in as the medic, only two men – the ship's doctor and a second patient – were showing signs of illness.

'At the time, neither one of them looked critically ill', Kornfeld adds: 'But the fear with Hantavirus is you can go from seriously ill to critically ill very quickly.'

Medical supplies on board are limited to over-the-counter medications, oxygen tanks and – fortuitously – plenty of aprons, gloves, surgical masks and respirators.

'Dr Steve' as Kornfeld is now known, has, thankfully, now been joined by two infectious-disease specialist doctors from the Netherlands. 'If I'm not helpful any more, I'm happy to just fade back and become a passenger again,' he said.

For now it seems the remaining passengers have reached an optimistic equilibrium.

Travel influencer Jake Rosmarin took to his Instagram stories on Thursday. 'Still in good spirits and continuing en route to the Canary Islands,' he wrote in the onscreen caption of a photo showing him smiling on an outdoor balcony of the ship overlooking the Atlantic.

Meanwhile, Jordanian influencer Kasem Ibn Hattuta told the Daily Mail: 'We finally left Cape Verde which was a relief for everyone on board, specially knowing that our sick colleagues are finally getting the medical care they need.

'Everyone is keeping high spirits, people are smiling and taking the situation calmly.

But what of all the other countries on the ever-growing map of potential infection?

Inevitably, a ripple of panic has spread among those watching scenes on television screens earlier this week of masked medics in protective suits.

The WHO has been quick to stress that there is no cause for alarm, that this is not the next pandemic, and that this virus spreads only through close and prolonged contact.

Pandemic or not, much like during Covid, scientists in South Africa, Senegal, Switzerland, the Netherlands and Argentina, among others, are now racing to unravel the origins of the virus and ensure this remains an isolated tragedy.

Away from the ship, a vast contact-tracing enterprise is under way, while in Argentina, experts are trying to trace just where the infection began.

With the Dutch husband and wife's movements being probed in particular, investigations are focusing on a wildlife-rich landfill site on the outskirts of Ushuaia, the capital of Tierra del Fuego, home to a type of rat that can carry the contagious Andes variant of the Hantavirus.

Whether that is the source of the contagion remains to be seen. The province of Tierra del Fuego has, the Daily Mail has learned, no recorded presence of Hantavirus and has not registered human cases since mandatory notification began in 1996.

While most Hantaviruses are caught by inhaling particles released by rodent droppings, urine or saliva and cannot be passed human-to-human, the Andes variant is an exception as it can spread between people, sparking outbreaks.

The virus can cause an often fatal lung disease known as Hantavirus pulmonary syndrome, which had a 32 per cent mortality rate among cases in Argentina last year.

In 2018, there was a 'super-spreader' incident in the country's Andean region where, following a birthday party, nearly three dozen people became ill and 11 died, so it is possible the Dutch couple contracted it elsewhere on their travels.

Paul Hunter, a professor in medicine at the University of East Anglia who specialises in infectious diseases and health protection, told the Daily Mail a cruise ship is an ideal setting for transmission. 'Cruise ships are very insular environments. People are in close contact with each other for several days or weeks and the age distribution means that they tend to be older and more vulnerable.'

He adds, however: 'Although it can take up to eight weeks, most people get the infection early on – within two or three weeks. The passengers who left the ship probably would have gone down ill by now if they were going to.'

As the world watches and Tenerife anxiously prepares for the arrival of MV Hondius, it is to be hoped he is proved right.

Additional reporting Tim Stewart.