Vang Vieng is an unlikely party hub.

Surrounded by striking limestone mountains and caves in central Laos, it morphed from a small farming town to a hedonistic party hub in the early 2000s. Enticed by boozy tubing experiences, throngs of twentysomething backpackers cemented its spot on south-east Asia’s famed backpacker trail.

A voyage through the tapestry of the region is somewhat of a rite of passage for some young travellers.

But the deaths of six young travellers – after a suspected mass methanol poisoning – emerged from the town and rippled through international headlines.

While a spate of backpacker deaths led to a crackdown on bars and a temporary tubing ban in 2012, Vang Vieng, a 90-minute drive from the capital Vientiane, has remained popular among tourists.

On Friday, the 19-year-old Australian Holly Bowles became the sixth person to die from the suspected consumption of drinks laced with methanol. News of her death came just hours after that of British lawyer Simone White, 28. Bowles’s best friend, Bianca Jones, 19, died on Thursday in hospital in Udon Thani, in Thailand, near the northern border with Laos. Thai authorities confirmed the Melbourne teenager died due to methanol poisoning.

Three other tourists – two Danish citizens, 19 and 20, and an American – died in Laos after the poisoning. About 11 foreign citizens remain in hospital.

Authorities in Laos on Friday detained the manager and owner of the Nana backpacker hostel in Vang Vieng, but no charges have been laid.

Families around the world are now desperately searching for answers. How could something like this happen?

‘I started to feel strange’

Almost a year ago, Claire*, a thirtysomething British traveller, was gazing up at the Lao sky, vodka and cola in hand. Her “tipsy tubing” trip last December had begun as planned.

But after the first stop at a makeshift riverside bar, in Vang Vieng, the trip went awry.

“I started to feel strange, suddenly I was very weak and tired, and I was sliding in and out of consciousness,” Claire says.

Her friends witnessed her eyes rolling back, and Claire remembers them later describing it as “terrifying”.

“I was mostly aware of everything but couldn’t see – I knew I was being carried but couldn’t physically do anything,” she says.

“I remember that I was trying to explain that something wasn’t right – that I wasn’t simply drunk.”

The incident landed her in hospital for days. She still doesn’t know how it happened.

“It could have been spiking, could have been bad alcohol poisoning,” Claire says.

“We had been warned off drinking spirits in Laos as there were tales of it being bad alcohol, but the drinks we’d had up until the first river stop [at an informal bar] had been bought from a supermarket in Vang Vieng, and the one drink I had bought had been in a bottle.”

Claire had been staying at the Nana Backpacker Hostel – where Jones and Bowles had stayed before they fell critically ill after a night out at Vang Vieng’s party spots.

The pair, aged 19 and from Melbourne, were on a “dream getaway”, Jones’s family said.

A selfie of Jones, posted this month on Facebook, shows her lounging in a tube on a river.

On the night of 11 November, Jones and Bowles went out to some bars in Vang Vieng, according to a hostel staff member, who spoke to the media.

The hostel’s manager, Duong Duc Toan, has said he served Jones and Bowles free shots of local vodka before they headed out, but vehemently denies that this made them ill.

What should have been a carefree night out left them bed-ridden for 24 hours. After the pair failed to check out of the accommodation as planned on 13 November, they sought help from hostel staff, who transported them to hospital.

In another hospital bed lay Simone White.

A lawyer who had worked with the global law firm Squire Patton Bogg, White was from Orpington, in south-east London, and was among as many as six British nationals who required treatment after the incident in Vang Vieng.

Her death in Laos was confirmed just hours after that of Jones, who had been transported to neighbouring Thailand after falling ill last week.

Prior to her death, Jones’s family said they hoped the Lao authorities would “get to the bottom of what happened as soon as possible”.

On Thursday, the Australian prime minister, Anthony Albanese, told parliament Jones’s death was “every parent’s worst fear”, while her family said she died “surrounded by love” in a statement to the Melbourne newspaper the Herald Sun.

Nick Heath, the president of the Beaumaris Football Club where Jones and Bowles had played Australian rules football, describes them as “part of the Covid generation”.

“They’d finished their schooling and both worked hard in their part-time jobs to get some money to have their dream overseas trip,” he told the ABC on Friday.

“Off they’ve went full of zest for life and quest for adventure.”

On Thursday, Thai authorities said Jones died from “brain swelling due to high levels of methanol found in her system”.

On Friday, Bowles died surrounded by family at a Thai hospital.

“It is with broken hearts and we are so sad to say that our beautiful girl Holly is now at peace,” her family said in a statement.

The Nana hostel declined to comment to the Guardian, saying they were working with the police to identify where the poisonous alcohol had been consumed.

Just 30ml can be deadly

When announcing the deaths of their citizens this week, the Danish and US governments made no link to methanol – although New Zealand’s foreign ministry said one of its citizens that had fallen ill could be a victim of methanol poisoning.

But as Lao authorities continue investigating the cases, experts say the clinical signs point to methanol poisoning.

“The minute you have people drinking and getting sick in a high number and the symptoms start after a certain time, that is methanol until proven otherwise,” said Norwegain professor Knut Erik Hovda, who works with Médecins Sans Frontières (MSF, or Doctors Without Borders) on the issue.

Samples were sent to Thailand and verified, says Hovda.

In south-east Asia, brewing bootleg liquor from ingredients such as rice and sugarcane is a cultural norm. Sometimes, these are mixed with methanol as a cheaper alternative to ethanol.

While ethanol, the key component of alcoholic drinks, can be safely consumed in small amounts, methanol is toxic to humans.

Just a single mouthful – 30ml – can be deadly.

Australia’s foreign affairs minister, Penny Wong, on Thursday said drink spiking and methanol poisoning were “far too common” in many parts of the world.

“I would say to parents, to young people, please have a conversation about risks, please inform yourselves. Please, let’s work together to ensure this tragedy doesn’t happen again,” she said.

Asia has the highest prevalence of methanol poisoning globally, with incidents in Indonesia, India, Cambodia, Vietnam and the Philippines, according to data from MSF.

Untreated, methanol poisoning has a fatality rate of between 20% and 40%, but if correctly diagnosed and treated in time, the survival rate is high, according to MSF.

“Once you recognise the clinical signs and symptoms of it and you give the proper treatment, you will not have any morbidities and complications,” says Dr Chenery Ann Lim, who oversees MSF’s methanol poisoning project.

There are two antidotes for methanol poisoning: one is ethanol, which is readily available, while the other is fomepizole.

It is impossible to tell if your drink has been made with poisoned alcohol, meaning travellers, especially in south-east Asia, have to be careful about what they consume, says Dr Dicky Budiman, a public health expert from Australia’s Griffith University.

“The clear message for young travellers is that if they are offered illegal or bootleg alcohol or local drinks, it is best to avoid it,” he says.

But Hovda says the numbers out of Laos are just the “tip of the iceberg”, with tourist horror stories accounting for just a fraction of cases.

In 2018, for example, more than 80 people died from drinking bootleg liquor in Indonesia, while more than 100 others were hospitalised.

“Very often this affects the poorest of the poor that nobody cares about,” Hovda says.

According to Chenery, “The majority of cases we are observing are really the head of the family, the males, the breadwinners.”

*Name has been changed