Driving research of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME / CFS),
Post Treatment Lyme Disease Syndrome (PTLDS), Fibromyalgia and Post COVID .

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex illness with a complex history. The best way to understand ME/CFS as we know it today is to understand the history of how it was first defined and how the diagnostic criteria has evolved over the past few decades.

Summary of the 5 major diagnostic criteria from 1988 onwards.
What's in a name after all?


Early misunderstanding
and ‘Neurasthenia’

In the 19th century the concept of ‘neurasthenia’ was introduced by psychiatrist George Beard, which defined an illness largely found in women with symptoms very similar to ME/CFS.

It was generally triggered by an infection and it was described as a "...condition of nervous exhaustion, characterized by undue fatigue on [the] slightest exertion, both physical and mental... the chief symptoms are headache, gastrointestinal disturbances, and subjective sensations of all kinds.” The diagnosis of neurasthenia declined in the early 20th century as its usefulness and validity were called into question.

Outbreaks of the 20th century
and the first definition of ME

Throughout the 20th century, there were about 70 possible documented outbreaks of ME/CFS. The condition went by many names but all were linked by their unknown cause and similar symptoms.

One of the most significant outbreaks in the history of ME/CFS was at the Royal Free Hospital in the United Kingdom. Over 200 staff were hospitalized, and the hospital closed for several months due to an unknown illness. During this time, Dr. Melvin Ramsay of the Royal Free Infectious Diseases department called the illness Myalgic Encephalomyelitis (ME).

Dr. Ramsay's definition remains one of the most accurate clinical descriptions of the illness, and several years later the condition would be recognized by the World Health Organisation in 1969.

Centers for Disease Control and Prevention (CDC) and CFS

Several significant US outbreaks led the CDC to put together a working group to reach a consensus on the definition and clinical description of these illnesses. This group recognized that the many outbreaks had to be known by many other names, including ME. They put together the first description of Chronic Fatigue Syndrome (CFS) in 1988 in order to classify the disease population to improve comparability and reproducibility for research purposes.

In 1994, the definition of CFS was loosened. This criteria has since been criticized for its broad definition that significantly increases the chances of misdiagnosis and impacts the effectiveness research. Furthermore, the name has been faulted for misrepresenting the severity of the illness.

The re-introduction of ME as ME/CFS
In 2003, the development of Canadian Consensus Criteria further refined the definition of ME/CFS. The key change was requiring the presentation of the symptom post-exertional malaise, a symptom named for ME and distinct from symptoms experienced in most other chronic disorders. The International Consensus Criteria removed fatigue as a required symptom in 2011, putting more emphasis on the other symptoms of the disorder in an effort to refine the diagnosis to symptoms which are distinct from other chronic disorders.
The improvement of research
With an improved diagnostic criteria, the quality and consistency of research into ME/CFS began to improve. The specificity of the diagnostic criteria has resulted in tighter cohorts for comparison to healthy subjects in research studies. The specific criteria, however, also reduced the prevalence of the disorder, including among previously diagnosed CFS patients who no longer fit this symptom set.

Disclaimer: This website is for informational purposes only. The information provided on this website is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

Stay Informed

Be the first to hear our research news.

Subscribe Now.

No thanks

Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME / CFS) Post Treatment Lyme Disease Syndrome (PTLDS), Fibromyalgia Leading Research. Delivering Hope.Open Medicine Foundation®


Averting a second pandemic:

Open Medicine Foundation leads groundbreaking international study of

Long COVID’s conversion to ME/CFS

AGOURA HILLS, CALIF.  — Open Medicine Foundation (OMF) is leading a large-scale international collaborative study investigating the potential conversion of Post-Acute Sequelae SARS-CoV-2 infection — more commonly known as Long COVID or Post-COVID Syndrome —  to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a chronic, life-altering disease with no known cause, diagnostic test or FDA approved treatments available.

Up to 2.5 million people in the U.S. alone suffer from ME/CFS; the COVID-19 pandemic could at least double that number. An estimated 35 percent of Americans who had COVID-19 have failed to fully recover several months after infection, prompting many to call it “a potential second pandemic.”

OMF recognized a familiar health crisis emerging, one with eerie similarities to ME/CFS. This crisis presented a unique opportunity to understand how a viral infection — in this case COVID-19 — may develop into ME/CFS in some patients. The goal is to find targeted treatments for ME/CFS patients and ultimately prevent its onset in people infected with SARS-CoV-2 or other infections.

The federal government is only now investing in Post-COVID research, with no focus on its connection to ME/CFS. OMF has already engaged researchers for the largest-scale study of its kind, solely supported by private donors who have contributed over one million dollars to date. When fully funded, the five million dollar, three-year study will be conducted across the globe at OMF funded Collaborative Research Centers, led by some of the world’s top researchers and ME/CFS experts.


In a significant percentage of patients, infections preceded their development of ME/CFS.  For example, according to the CDC about one in ten infected with Epstein-Barr virus, Ross River virus, or Coxiella burnetti develop symptoms that meet the criteria for ME/CFS.


The ability to follow the development of ME/CFS from a known viral infection is unprecedented to date and crucial to researchers’ understanding of the disease. The focus of this study is to find the biological differences between persons returning to good health after COVID-19 and persons who remained ill more than six months after infection and developed ME/CFS.  Understanding these alterations in key pathways can lead to groundbreaking discoveries including new biomarkers, drug targets, and prevention and treatment strategies.


About Open Medicine Foundation

Established in 2012, Open Medicine Foundation leads the largest, concerted worldwide nonprofit effort to diagnose, treat, and prevent ME/CFS and related chronic, complex diseases such as Post Treatment Lyme Disease Syndrome, Fibromyalgia, and Post COVID. OMF adds urgency to the search for answers by driving transformational philanthropy into global research. We have raised over $28 Million from private donors and facilitated and funded the establishment of five prestigious ME/CFS Collaborative Research Centers around the world. To learn more, visit www.omf.ngo.


Heather Ah San

Development and Communications Manager