🗓️ Last updated: January 2026
Advances in Research and Diagnosis
“This page aims to inform and share the current state of knowledge, without claiming to be exhaustive or to represent an absolute truth. It will be updated monthly if developments in the situation require it.”
Patients and researchers agree that ME/CFS is likely one of the most severe diseases known — not because of mortality rates, but because of the profound physical, cognitive, and social devastation it causes in those affected.
According to recent meta-analyses (2023–2025), the prevalence of ME/CFS in the general population is estimated to be around 0.2 to 1%, with a pooled estimate close to 0.89% (confidence interval 0.60–1.33%). Applied to the global population, this would represent approximately 30 to 70 million people affected. These figures should be considered orders of magnitude, as underdiagnosis remains widespread and study methodologies are highly heterogeneous.
The impact of the COVID-19 pandemic has significantly increased this prevalence, with estimates suggesting that approximately 6 to 7% of adults in the general population are affected by Long COVID (around 400 million people by the end of 2023). However, the exact proportion of Long COVID cases that evolve into a full clinical picture of ME/CFS remains poorly defined, although several studies suggest strong symptom overlap.
👉 It is as if the entire population of France were bedridden by chronic exhaustion.
Diagnosis currently relies on a process of exclusion: all other possible causes of extreme fatigue must first be ruled out (cancer, diabetes, autoimmune diseases, etc.).
👉 This involves numerous tests, which are often lengthy, costly, and exhausting.
On average, the diagnostic journey can last 2 to 3 years or more
before the verdict is finally delivered:
“You have Myalgic Encephalomyelitis – Chronic Fatigue Syndrome”
🔬 Recent advances in ME/CFS diagnosis (2023–2025):
Promising biomarker pathways are emerging, and machine learning models are beginning to be explored, but to date no single, reliable, and officially approved test exists.
🔍 1. Immune and inflammatory markers
- Cytokines: some studies show abnormal levels (e.g., IL-6, IL-10, TNF-α), particularly during the acute phase or after exertion.
- NK (Natural Killer) cells: reduced numbers or impaired function.
➡️ These abnormalities are not yet 100% specific, but they are part of a combined set of potential biomarkers.
🧠 2. Brain imaging & perfusion
Increasingly, objective abnormalities are being observed: alterations in cerebral blood flow and inappropriate activation of certain brain regions during cognitive tasks. These findings support the hypothesis of a real neurological dysfunction.
🧪 3. Cellular metabolism & energy production
Research shows alterations in mitochondrial metabolism, reduced ATP production, and a state resembling “cellular hibernation” in some patients.
💡 4. Two-day cardiopulmonary exercise testing (2-Day CPET)
This test remains a reference standard in some centers for objectively demonstrating
post-exertional malaise (PEM):
ME/CFS patients show an abnormal decline in performance on the second day after exertion.
⚠️
This test is extremely demanding for patients, but remains strong clinical evidence.
🧬 5. Recent experimental biomarkers (2023–2025)
In 2024–2025, multi-omics studies (proteomics, metabolomics, transcriptomics) combined with machine learning identified biomarker panels with an AUC of approximately 0.83 in certain cases.
Example: a 2024 study identified a signature of 9 biomarkers plus 19 clinical features to classify ME/CFS with approximately 83% accuracy.
🔚 Conclusion
No single test has yet been standardized or officially approved, but:
- Research is progressing rapidly, despite a severe lack of financial support.
- Findings are converging toward a better pathophysiological understanding.
- Many countries are now developing serious and collaborative protocols.
🇦🇺 Australia – 🇳🇴 Norway – 🇺🇸 United States – 🇫🇷 France (INSERM) – 🇯🇵 Japan – 🇬🇧 United Kingdom
🌍 Countries most affected by ME/CFS
Approximate estimate (post-COVID & long forms)
These figures take into account the likely increase in cases following the COVID-19 pandemic.
| Country / Region | ME/CFS cases (pre-COVID) | Cases including Long COVID | % of population (Long COVID) | Long COVID source |
|---|---|---|---|---|
| 🇺🇸 United States | 1 to 2.5 million | ≈ 18.6 million | ≈ 6.9% | CDC (2022) – 6.9% of adults had Long COVID |
| 🇬🇧 United Kingdom | 250,000 to 500,000 | Not reported | — | No recent data available |
| 🇯🇵 Japan | 300,000 to 800,000 | Not reported | — | No recent data available |
| 🇨🇳 China | Likely > 2 million | Not reported | — | No reliable data available |
| 🇦🇺 Australia | 100,000 to 250,000 | Not reported | — | No recent data available |
| 🇨🇦 Canada | 500,000 | ≈ 1.4 million | ≈ 4.6% | Statistics Canada – 4.6% of adults |
| 🇳🇴 Norway | 20,000 to 30,000 | ≈ 974,000 | ≈ 17.4% | National study – 17.4% persistent fatigue at 12 months |
| 🇫🇷 France | 300,000 to 600,000 | ≈ 2,060,000 | ≈ 4% | Santé publique France – 4% of adults (summer 2022) |
| 🇩🇪 Germany | 140,000 to 310,000 | Not reported | — | No recent data available |
| 🌍 World (estimate) | ~30 to 40 million | ~60 to 70 million | ~1% of the global population | WHO synthesis / Long COVID studies 2023–2024 |