It was unusual enough for a previously healthy 37-year-old man to suffer from a sudden perforated oesophagus, an uncommon and potentially fatal condition usually caused by prolonged, forceful vomiting.

But even more strange was that the man, who was also suffering from severe abdominal and chest pain when he arrived at a Sunshine Coast hospital, had three small, dark burn marks in a line on his left shoulder.

As hospital staff asked him standard questions about what he had been doing before becoming unwell, the man said he had taken part in a kambo ritual.

“What the heck is kambo?” junior doctor Christopher Darlington recalls asking himself as he assisted his colleagues in treating the patient, who required surgery to repair his oesophagus and spent 18 days in hospital.

“I’d never heard of it. And then I found out its use had come out of the Amazon as part of a tribal ritual and that somehow, as a result, we were dealing with an oesophageal perforation on the Sunshine Coast.

“How does that happen?”

It was the first case of a perforated oesophagus caused by a kambo ritual in Australia and only the second kambo-related case worldwide, prompting Darlington to write about the patient in a paper published in April in the journal Oxford Medicine Case Reports.

Darlington is concerned other cases may emerge and says doctors need to be aware.

What is kambo?

Kambo is the name given to secretions from a species of giant leaf frog native to South America. It is used as part of traditional cleansing ceremonies conducted by Indigenous tribes in the Amazon.

A 2022 paper published by Brazilian doctors in the journal Frontiers in Pharmacology describes how the slow movements of the frog mean it can be easily captured by shamanic healers. Once captured, it is stretched out in the shape of an X over branches, its front and back legs bound.

The frog is poked and prodded until the kambo is secreted from the skin, which is then scraped off with a stick. Then the frog is released – Indigenous healers believing harming the frog angers animal spirits.

During purification rituals, a shaman healer burns a line of dots into the participant, with the number of burns varying depending on factors such as the body part and the gender of the participant. The kambo is then applied to the burns. The participant drinks large amounts of liquid before the kambo is applied.

“Reactions are often strong and include tachycardia [increased heart rate], sweating, and severe vomiting … followed by a state of apathy and drowsiness,” the Frontiers in Pharmacology paper said.

This ritual has been adopted by the alternative health movement, including by people claiming to be shamanic healers in Australia, who incorporate its use as part of cleansing rituals.

In his paper, Darlington wrote: “The rise of the global alternative health movement has seen the spread of many cultural rituals far from their origins. This is problematic as people may undertake such practices unaware of possible risks, steps in preparation or traditional dosages.”

Kambo use has now been implicated in deaths worldwide, two of them in Australia.

Jarrad Antonovich, 46, died after using kambo at the Dreaming Arts festival in New South Wales in 2021. His oesophagus ruptured after severe and repeated vomiting due to kambo and consumption of ayahuasca, a South American psychedelic. Natasha Lechner died in 2019 aged 39 in a shamanic kambo ritual in Mullumbimby that went tragically wrong.

Sounding the alarm

Prof Vidal Haddad Jr, a toxicologist at the São Paulo State University in Brazil, is concerned by the trend.

In a paper published in the Journal of Venom Research, Haddad described how Brazil has seen a spate of deaths as kambo is adopted by urban therapy clinics.

Haddad says he became interested in kambo after “a tragic event” in which a patient with heart problems died after taking part in the ritual.

“I was trained as a doctor and biologist and I knew the pharmacological and sometimes toxic properties of the secretions of the species,” he says. He wrote about the case and others in the paper “as an alert for health teams”.

Given how rare the kambo ritual is even among Indigenous Amazon tribes, he says, it is unlikely that anyone outside those tribes can claim to be knowledgable in it.

“I’ve worked on several projects at the Amazon,” he says. “The Indigenous people who use kambo live in restricted areas of the Amazon region and the ritual is not disseminated by the many tribes there. Elsewhere, this trade is done illegally and the extraction of secretions is simple, which allows traffickers to do this.”

He says it is unlikely those tribes who still practise the ritual are aware it has been co-opted by the western wellness movement.

“Kambo rituals aim at physical and spiritual improvement, and to bring luck in fishing and hunting, and in [treating] the negative state of mind that causes illness,” Haddad said. “They are always supervised by their shamans, who have thousands of years of knowledge in the use of the toxins. Indigenous people do not do it constantly, only in situations where effects are needed.”

‘Exploiting people’s gullibility’

While kambo is banned in Australia, it is sold illegally online and there is no way to tell whether the substance is legitimate or sourced without harm to animals, says Prof Roger Byard, a forensic pathologist at Adelaide University.

In a paper published in the journal of Forensic Science, Medicine and Pathology, Byard wrote that “in addition, these products may be adulterated with heavy metals, standard pharmaceutical agents or parts of endangered plant and animal species”.

He says the adoption of wellness rituals involving kambo and other little-known substances could have implications for pathologists conducting autopsies if they don’t know the substance has been used or ingested and therefore may not be able to identify it as being involved in a death.

“Routine toxicology doesn’t look for these sorts of preparations,” Byard says.

He describes the adoption of kambo and other Indigenous rituals by so-called wellness healers in Australia and other countries as “an example of western arrogance”.

“A lot of these western wellness practitioners are exploiting people’s gullibility and exploiting those who are sceptical about western medicine,” Byard says.

“But the techniques of shamans and healers in Indigenous communities have been used for hundreds of years and they have been trained to safely use these substances for certain, specific situations.

“Yet it is being promoted here in Australia that kambo can be used for everything from chronic fatigue syndrome, anxiety, vascular problems to Parkinson’s disease when there’s no evidence for that. To think that we can go into a community or spend a bit of time in another country and then take one of their time-honoured, cultural practices and then just take it for our own use is absolute western arrogance.”

• Do you know more? melissa.davey@theguardian.com