The world's first blood test for chronic fatigue syndrome has been developed with the help of researchers from an Oxford firm.

The test is designed to identify myalgic encephalomyelitis, also known as chronic fatigue syndrome or ME/CFS, a long-term condition affecting more than 400,000 people in the UK.

CFS/ME is characterised by severe, persistent fatigue, but there is no current test for the condition and medics usually diagnose patients based on their symptoms.

Lead researcher Professor Dmitry Pshezhetskiy, from the University of East Anglia's Norwich Medical School, said: "This is a significant step forward.

"For the first time, we have a simple blood test that can reliably identify ME/CFS.

"We know that some patients report being ignored or even told that their illness is 'all in their head', with no definitive tests, many patients have gone undiagnosed or misdiagnosed for years.

"We wanted to see if we could develop a blood test to diagnose the condition - and we did.

"Our discovery offers the potential for a simple, accurate blood test to help confirm a diagnosis, which could lead to earlier support and more effective management."

Scientists led by experts from UEA and Oxford Biodynamics set out to examine how DNA is folded in patients diagnosed with ME/CFS, which might provide tell-tale signs of the condition.

Oxford BioDynamics has its headquarters at ARC Oxford(Image: ARC)

Researchers analysed blood samples from 47 patients with severe ME/CFS and 61 healthy individuals, finding a unique pattern present only in those with the condition.

The study reported the test has a sensitivity - the likelihood of a test being positive if that patient has the condition - of 92 per cent and a specificity - the probability the test will rule out negative cases - of 98 per cent.

Alexandre Akoulitchev, chief scientific officer at Oxford BioDynamics, said: "The EpiSwitch platform behind this test has already been proven to deliver practical, rapid blood diagnostics accessible at scale.

"With this breakthrough, we are proud to enable a first-in-class test that can address an unmet need for a quick and reliable diagnostic for a complex, challenging-to-identify illness."

However, other experts have called for more studies to confirm the finding, and for the test to be assessed among a wider population of patients.

Professor Chris Ponting, chairman of medical bioinformatics at the University of Edinburgh, said: "This test needs to be fully validated in better-designed and independent studies before it is considered for clinical application.

"Even if validated, the test will be expensive, likely (about) £1,000."

Researchers said they hope the development will also pave the way for a test to diagnose long Covid.