The full story
This is the episode's narration, word for word. Headings jump to that point in the video.
The question 0:00
How do you prove that a germ causes a disease, when almost every expert is sure it can't? In 1984, a young doctor in Perth tried the most direct way there is. He drank a beaker of the bacteria. To see why, and why it still wasn't enough, start with what everyone knew about ulcers.
What everyone knew 0:23
A peptic ulcer is a raw crater in the lining of the stomach, or of the duodenum, the first stretch of gut just past it. Ulcers can bleed, and a deep one can burst through the wall, sometimes fatally. In 1982, the cause was considered settled. Too much acid, driven by stress, personality, smoking or your genes. A motto coined in 1910 summed it up: no acid, no ulcer.
Treating the acid 0:53
So doctors went after the acid. Marshall later said healing an ulcer with chalky antacid took about a bucketful over four weeks. Surgeons cut the nerve that drives acid, or removed the lower third of the stomach. Then came acid-blocking pills like Tagamet, which by Marshall's account earned its maker about a billion dollars a year by 1983. They healed ulcers, but stop the pills and the ulcer almost always came back.
The sterile stomach 1:23
And bacteria? For a century, medical students were taught that bacteria can't grow in the stomach. It's full of acid. The pathologist Robin Warren said it was treated as a known fact, like everyone knowing the earth is flat. There was a practical reason, too. Stomachs removed in surgery were clamped shut and soaked slowly in preservative, so the lining digested itself and any bacteria vanished.
Seen, and ignored 1:52
Yet people had seen spiral bacteria in stomachs for about a hundred years. In the late eighteen-hundreds, Walery Jaworski in Kraków described them in human stomach washings. In 1940, a Harvard team saw them in forty per cent of stomachs removed for ulcer or cancer. But in 1954, a leading American gastroenterologist, Eddy Palmer, looked at 1,180 people and found none. His method wasn't suited to spiral bacteria, but the idea was already out of fashion, and his result seemed to settle it.
A thin blue line 2:33
Robin Warren was born in Adelaide in 1937 and worked as a pathologist at Royal Perth Hospital. By the late nineteen-seventies, the new flexible endoscope meant doctors were sending him small, well-preserved biopsies of stomach lining. In June 1979, on his forty-second birthday, one biopsy showed a thin blue line along the surface. Under a silver stain, the line turned into masses of small, curved, spiral bacteria, packed against the cells.
Nobody could see them 3:06
His colleagues couldn't see them at first. Once they could, they decided the bacteria didn't matter, and challenged him to find more. He kept looking, and found them in about a third of stomach biopsies. Wherever they were, the lining underneath was inflamed, a condition called gastritis. Among twenty normal biopsies from the same part of the stomach, he found none. But clinicians didn't believe it: "Everybody knows the stomach is sterile".
The registrar 3:39
In the second half of 1981, a Kalgoorlie-born trainee physician, Barry Marshall, needed a research project. His bosses sent him down to Warren's office. Warren said Marshall was the first person to show any interest in his work. Warren would do the pathology, and Marshall the patients and the attempts to grow the bacteria.
It won't grow 4:03
In 1982 they started a study of a hundred patients having an endoscopy. The bacteria were easy to see under the microscope, but nothing grew. They were using the right method, borrowed from Adrian Lee in Sydney, with a low-oxygen atmosphere, because this bacterium dislikes ordinary air. Month after month, the plates came back empty.
Easter, 1982 4:28
Then came Easter. Patient thirty-seven was biopsied on the Thursday before Easter 1982. The lab was swamped, nobody checked the plates on the Saturday, and they sat in the incubator until Tuesday, five whole days. On Tuesday, small, clear colonies had grown. Then John Pearman's lab confessed. They'd been treating these plates like throat swabs, and throwing them out after forty-eight hours. This bacterium just needed longer to grow. As Marshall put it, he'd been wasting his time for six months.
Thirteen heads in a row 5:05
When the results came back, fifty-eight of the hundred patients carried the bacteria. Every one of the thirteen with a duodenal ulcer had them. Marshall compared it to tossing a coin thirteen times and getting heads every time, which happens less than once in a thousand tries. The four stomach-ulcer patients without them were taking anti-inflammatory painkillers, the other main cause of ulcers. Still, as Marshall put it, who would overturn ulcer medicine on thirteen patients from Perth?
How does anything live in acid? 5:39
So how does a bacterium survive in a bath of acid? Mostly, it doesn't sit in the acid at all. It lives in the layer of mucus that coats the stomach lining, where the acidity is far milder. To get there, it carries an enzyme called urease, which splits urea, a natural waste product, into ammonia. The ammonia is alkaline, and it helps the bacterium survive the acid for the short dash to shelter, though exactly how is still debated. Then its corkscrew shape and whip-like flagella drive it into the mucus, against the cells.
Why the duodenum? 6:18
But if the bacterium lives in the stomach, why are most ulcers just past it, in the duodenum? The current view is that infection inflames the lower stomach and upsets the stomach's acid control, so the healthy upper stomach makes more acid. That extra acid pours into the duodenum. So the acid theory wasn't wrong, just incomplete. The acid does the damage, and the infection is why it gets out of hand, and why ulcers kept coming back.
Like a religion 6:50
In June 1983, the pair published two letters in The Lancet. When they sent in the full paper, the editors couldn't find a reviewer who believed it. It was published only after Martin Skirrow's lab in England repeated the work. A common reply was that the bacteria simply moved into stomachs that were already damaged. Marshall wrote that the medical understanding of ulcers was akin to a religion.
Koch's checklist 7:17
To prove a germ causes a disease, microbiologists had a checklist from 1884, Koch's postulates. Find the microbe in the disease, grow it pure, give it to a healthy host and get the disease, then find it again. Warren and Marshall had roughly the first two. For the third you'd normally infect an animal, but in January 1984 Marshall's piglets refused to catch it. And Marshall reasoned that the only person who could truly consent to the risk was himself.
The drink 7:53
So in 1984, Marshall infected himself. First, an endoscopy showed his own stomach was healthy. He didn't ask the ethics committee, and he didn't tell his wife beforehand. A colleague, Neil Noakes, mixed a culture into a broth, and Marshall drank about fifty millilitres of cloudy brown liquid. Then, around days five to eight, he woke vomiting, and his breath turned foul. On day ten, his biopsy was teeming with the bacteria, and his stomach lining was inflamed.
What the drink proved 8:29
By day fourteen it was clearing up, before he'd taken any antibiotic. It showed that the bacterium could infect a healthy stomach and cause gastritis. It did not give him an ulcer. So his paper, published in 1985, was honestly titled an "attempt" to fulfil Koch's postulates. In New Zealand, a doctor named Morris swallowed the bacterium too, and his gastritis took years to cure. And why did no patient remember catching it? Most people pick it up as small children, then carry it silently for life.
The proof was the trial 9:08
What changed most minds wasn't the drink. It was trials. In Marshall's double-blind study in Perth, ulcers stayed healed when the bacteria were cleared, and came back when they weren't. By Marshall's count, when the bacteria stayed, you had to treat a hundred and four patients to get ten lasting cures; when they were cleared, only fourteen. Other teams confirmed it. In 1994, a US National Institutes of Health panel agreed that ulcer patients with the bacterium should have it treated.
The Nobel, and the credit 9:46
On the third of October 2005, Marshall and Warren were announced as joint winners of the Nobel Prize in Physiology or Medicine. Warren saw the bacterium, now called Helicobacter pylori, and tied it to gastritis. Marshall's study, with John Pearman's lab, grew it; together they tied it to ulcers and showed that clearing it could cure them. Marshall stressed they weren't alone: by the mid-1980s groups in Sydney, across Europe, in the US and in Asia were working on it. Warren died in 2024.
Cancer, too 10:27
By one large estimate, in 2015 more than half the people on Earth carried Helicobacter, about four point four billion, and it's been getting less common since. Most never get sick; something like one in ten to one in seven will have an ulcer at some point. In 1994, the World Health Organization's cancer agency declared it a definite cause of cancer. It's now linked to about ninety per cent of cancers in the main part of the stomach. Whether anyone should be tested or treated is a question for a doctor; this video is only the science and the history.
The next question 11:08
In 2018, Helicobacter was the leading infectious cause of cancer in the world. Close behind it was a virus, human papillomavirus, or HPV. Next time, two scientists in Brisbane, Ian Frazer and Jian Zhou, take that virus on. If a germ can cause a cancer, could you vaccinate against the cancer before it ever starts?
Sources
Every factual claim in the episode is tied to one of these. Spotted an error? Tell us.
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- Nobel Assembly at Karolinska Institutet, Press release, The Nobel Prize in Physiology… — nobelprize.org
- J. R. Warren, "Helicobacter – the ease and difficulty of a new discovery", Nobel… — nobelprize.org
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- D. Bordin and M. Livzan, "History of chronic gastritis: How our perceptions have… — pmc.ncbi.nlm.nih.gov
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Image credits
- Royal Perth Hospital, 2004 · photo Nachoman-au · CC BY-SA 3.0 · via Wikimedia Commons · licence: https://creativecommons.org/licenses/by-sa/3.0/
- Helicobacter pylori, electron micrograph · Yutaka Tsutsumi, Fujita Health University · free use · via Wikimedia Commons
- Barry Marshall, 2019 · photo Binarysequence · CC BY-SA 4.0 · via Wikimedia Commons · licence: https://creativecommons.org/licenses/by-sa/4.0/
- Robin Warren speaking on 'Discovering Helicobacter', Singapore, 2016 · photo Sinednov · CC BY-SA 4.0 · via Wikimedia Commons · licence: https://creativecommons.org/licenses/by-sa/4.0/
Researched and scripted with AI assistance, fact-checked claim by claim, with synthetic narration and diagrams drawn in code. How we make episodes.
