Underhill, Rosemary, Baillod, Rosemarie · Medicina (Kaunas, Lithuania) · 2020 · DOI
This study examined a major ME/CFS outbreak that occurred at Royal Free Hospital in London in 1955, which forced the hospital to close for three months. Researchers interviewed 27 former staff members who experienced the outbreak and found their descriptions matched an infectious illness affecting the lymph nodes, muscles, and nervous system—not mass hysteria as some had claimed 15 years after the event. The study provides firsthand evidence that the 1955 epidemic was a real physical illness, not a psychological one.
This study directly challenges the psychiatric dismissal of the Royal Free outbreak as 'mass hysteria,' which has been used historically to delegitimize ME/CFS as a real disease. By documenting eyewitness accounts from those who lived through the outbreak, the research supports the classification of ME/CFS as an organic infectious illness rather than a psychosomatic condition. This reframing has important implications for how ME/CFS is recognized, researched, and treated by the medical community.
This study does not definitively identify the specific infectious agent responsible for the 1955 outbreak, as no pathogen was isolated or confirmed through modern methods. The retrospective nature of the data means recall bias may affect accuracy of symptom descriptions from 1955. Additionally, the study cannot exclude the possibility that both infectious and psychological factors contributed to the outbreak's presentation or spread.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Underhill, Rosemary & Baillod, Rosemarie (2020). Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Organic Disease or Psychosomatic Illness? A Re-Examination of the Royal Free Epidemic of 1955.. Medicina (Kaunas, Lithuania). https://doi.org/10.3390/medicina57010012
BibTeX
@article{mecfsatlas-underhill-2020-myalgic-encephalomyelitis,
author = {Underhill, Rosemary and Baillod, Rosemarie},
title = {Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Organic Disease or Psychosomatic Illness? A Re-Examination of the Royal Free Epidemic of 1955.},
journal = {Medicina (Kaunas, Lithuania)},
year = {2020},
doi = {10.3390/medicina57010012},
note = {PubMed: 33375343},
url = {https://www.mecfsatlas.com/evidence/underhill-2020-myalgic-encephalomyelitis},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/underhill-2020-myalgic-encephalomyelitis
Contribute
Private, reviewed by a human. Not a public comment thread.