Published: 15:55 BST, 3 September 2026 | Updated: 19:28 BST, 3 September 2026
It's a seemingly remarkable claim about the root cause of multiple sclerosis – a devastating incurable illness that continues to baffle scientists.
Last month, US alternative medicine doctor Jessica Peatross boldly declared that 'the bacteria that triggers MS has been found.' Her post was shared thousands of times, sparking a huge online debate.
For the millions of people affected by the disease, the implications were potentially enormous.
MS affects around one million people in the US and around three million worldwide, causing loss of sight and balance, crippling fatigue, problems walking and, in severe cases, paralysis. Crucially, there is no cure, few effective treatments – and it's on the rise.
A 2023 study found that MS is becoming more prevalent and demographically diverse across the US.
Between 2010 and 2017, the cases per 100,000 residents rose from 309 to 362, according to figures from the National Multiple Sclerosis Society.
Doctors are also increasingly concerned that more young people are being diagnosed, while women are two-to-three times more likely to be affected by the condition than men.
Many who reacted to Dr Peatross's post were delighted that scientists had apparently finally begun to unravel one of the great mysteries surrounding the disease.
MS is on the rise among young people, research suggests. Pictured, Becky Lee, who began experiencing symptoms at just 21
Others were far more skeptical – challenging her credentials and questioning the evidence behind such an extraordinary claim.
Yet the Daily Mail can reveal there is serious science behind it.
Her claim is based on rigorous academic research suggesting that while MS attacks the brain and spinal cord, events that help set the disease in motion may begin somewhere entirely different: the gut.
Researchers at Germany's prestigious Max Planck Institute have identified two specific species of gut bacteria that appear capable of helping to trigger the immune response involved in MS.
Experts caution that this does not mean scientists have discovered a single 'cause' of the disease. MS is thought to arise from a complex interplay of genetic, immune and environmental factors, with obesity and infection from the Epstein-Barr virus among those linked to increased risk.
