70th Anniversary of Royal Free outbreak - 13th July, 1955 

14th July, 2025

The 13th of July 2025 marked the 70th anniversary of the outbreak of an illness which was, in a 1956 piece in The Lancet, labelled ‘benign myalgic encephalomyelitis’.  

At the start of the outbreak - on the 13^th of July 1955 - a doctor and nurse working at the hospital were admitted to wards with the ‘mystery illness’. By the 25th of July - only 12 days later - over 70 members of hospital staff were affected (The medical staff at the Royal Free Hospital, 1957).  

The outbreak at the Royal Free Hospital lasted until the 24^th of November 1955, at which point 292 members of hospital staff were affected, of which 255 were admitted to various hospitals. Oddly, although the hospital was full at the time of the outbreak, only 12 Royal Free patients were among those infected (Hyde, 1990).  

The exact reason why staff became unwell, and many patients did not, is unknown. However, Nuala Crowley and colleagues (Crowley et. al., 1957) noted that while patients remained in one place throughout the outbreak, staff moved around and were more likely to encounter one another - both on the wards, and in smaller rooms - increasing the likelihood of infection. Additionally, before the 24^th of July 1955, certain staff members from the Royal Free Hospital were shared with other institutions including the The Hampstead General Hospital and The Elizabeth Garrett Anderson Hospital. On the 24^th of July, although the main hospital closed, and staff were forbidden from carrying out duties at more than one hospital, employees from different sites still frequented the same tobacconist and stood together at the same bus stop.   

Was the Royal Free the first time M.E. was identified? 

Although the 1955 outbreak is considered to be a seminal moment in the history of M.E., it was not the first time the disease had been observed - in fact, the origins of M.E. may be described as “ancient” (Hyde, 1990), with references to a disease matching the symptoms of M.E. dating back to before 1900 BC. 

For example:

• In 1854, Florence Nightingale contracted an infectious disease in the Crimea, and although she recovered briefly, she fell ill again and developed chronic symptoms including chest pain, headaches, and rapid muscle fatigue. As it is ‘highly likely’ that Florence Nightingale had either CFS or ‘a disease indistinguishable from it’, International CINDS Awareness Day is observed on her birthday - 12th May.  

Was the Royal Free the first outbreak of M.E.?  

The outbreak at the Royal Free was not the first; there had been outbreaks prior to this such as those in Iceland (1948 -1949 resulting in the term ‘Iceland disease’ or ‘Akureyri Disease’) and subsequently (e.g. Incline Village, Lake Tahoe, Nevada (1984) of CFS). 

In fact, ME Research UK’s late Patron Dr. Parish compiled a list of such outbreaks spanning 1934 to 1980 (i.e. Los Angeles to Southampton), but there have been others since.  

In total, it is believed that approximately 70 outbreak incidents have been recognised. 

If the Royal Free wasn’t the first outbreak of M.E., why is it so important in the history of the disease?  

It is only epidemic outbreaks - alongside symptom-based observational diagnoses, health administration, advances in medical language, and advent of medical journals - which permit the systematic gathering of information and dissemination of case reports relating to a particular disease.   

The outbreak at the Royal Free was not the first. However, due to previous outbreaks of the illness, by 1955 there was enough information available for doctors to recognise a pattern, and act on the need to investigate the disease further.  

This produced two major outcomes which had not been seen before: 

1. The disease’s features and nature began to be studied in detail. 

2. Increased numbers of publications in medical journals speculating on the nature of the illness, and drawing upon earlier outbreaks including those by Naldrett White (1954) (Iceland Disease - A New Infection Simulating Acute Anterior Poliomyelitis) and E D Acheson (Encephalomyelitis Associated with Poliomyelitis Virus - an outbreak in a nurses’ home and The Clinical Syndrome Variously Called Benign Encephalomyelitis, Iceland Disease and Epidemic Neuromyasthenia - also a review there of by Dr. Parish), and by Dr. Melvin Ramsay.

As a result, the outbreak at the Royal Free can be considered as the ‘door opening event’ to an increase in research interest into the disease following other historical outbreaks such as those in Los Angeles in 1934, Iceland between 1948-1949, and in New York State in 1950. In recognition of the research generated by the outbreak at the Royal Free, ME Research UK is launched “ME Research Day” on the 13th of July 2025.

The following articles in this series will discuss:

• Why it was so hard to identify the cause of the outbreak, and the implications this had.  
• The significance of the outbreak at the Royal Free today.

References:

• The medical staff at the Royal Free Hospital. “An outbreak of Encephalomyelitis in the Royal Free Hospital Group, London, in 1955”. British Medical Journal. (1957)  

• Dr B. Hyde. Chapter 12, Section: ME (CFS): An Historical Perspective, in “The Clinical and Scientific Basis of Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome. (1990)” 

• Crowley N, Nelson M, and Stovin S. “Epidemiological aspects of an outbreak of encephalomyelitis at the Royal Free Hospital, London, in the summer of 1955“. Journal of Hygiene. 1957;55(1):102-122. doi:10.1017/S0022172400061295.