What Is ME/CFS?

(Myalgic Encephalomyelitis/Chronic Fatigue Syndrome)

A Short Introductory Leaflet Prepared by
Dr E G Dowsett MB ChB.Dip.Bact.
Honorary Consultant Microbiologist
South Essex Health Trust
©May 1997 (Revised February 1998)

Owing to its close clinical and epidemiological similarity to non-paralytic poliomyelitis, this illness was known as "atypical poliomyelitis" until the mid 1950's. A more descriptive term (myalgic encephalomyelitis) adopted in the UK (Lancet 1961) remains popular in many countries including Australasia. In 1988, new designations were put forward in the USA. The emphasis upon a single symptom (fatigue) has led to a diagnostic confusion which hampers research and, in 1998, American physicians are once more seeking a descriptive name!

ME is not a new disease but awareness has been raised by a striking new epidemiological feature of the 20th century - major epidemics of poliomyelitis followed sequentially, seasonally and geographically by a parallel increase in ME/CFS. 38 epidemics of ME/CFS were recorded during the last pandemic period of poliomyelitis (which was terminated in 1960's by successful immunisation). Since then, ME/CFS has continued, unabated, in a similar pattern. 25 further epidemics have been documented since 1965 including the 1984/1989 pandemic arising in North American and followed by increased prevalence worldwide.

ME/CFS occurs in sporadic, endemic and epidemic forms which, in the cooler and more temperate regions of the world, mainly afflicts those born into communities enjoying modern standards of hygiene. No government has yet funded a major demographic survey but individual studies estimate that some 5 million cases arc recognised between the USA, New Zealand and Europe of which possibly ½ million are reliably diagnosed in the UK. All ages and both sexes are susceptible with peak incidence between 30 and 40 years, followed by a sharp decline. Sex ratios may be equal in childhood but a significant secondary peak in incidence occurs at puberty, when females (who suffer a more chronic and disabling illness during childbearing years due to hormonal factors) outnumber males by 3:1.

Occupational exposure to infection (rather than to stress) underlies the high incidence in teachers and health care workers. Other high risk activities include child care, travel, watersports and employment in agricultural, water and waste disposal industries. It is logical to assume that ME/CFS, like paralytic polio, is a rare complication of a trivial but naturally immunising childhood infection with faecal-oral spread. Paradoxically, improvements in hygiene have disrupted universal herd immunity, permitting widespread susceptibility to neurological complications, rare or unknown in previous generations. Clustering of cases in families, institutions and schools suggest amplification of infection in the community via symptom free children. The coincidental re-emergence of the post-polio syndrome, which bears a close clinical and pathological similarity to ME/CFS will add to our knowledge of chronic neurological diseases associated with social and environmental change in the 20th century. [2]

In the majority of cases, ME/CFS is triggered by a short respiratory/gastrointestinal infection characterised by headache, nausea, sore throat, dizziness and malaise, with or without myalgia or lymphadenopathy. A more dramatic onset (e.g. following meningitis, vestibulitis or myocarditis) is also recognised though a more trivial prodromal infection may be forgotten. After a variable interval, a major systemic disease develops which is primarily neurological but may also affect cardiac and skeletal muscle, liver lymphoid and endocrine organs.

1. Neurological (a) Mypothalmic disturbance [1] - reversal of circadian sleep and temperature rhythm; failure to maintain osmoregillation, cortisol response to stress, glycaemic control, female hormone balance. Uncontrollable mood swings also occur (b) Cognitive dysfunction leading to difficulties with memory, concentration, word finding, numerical calculations, spatial perception, reading and writing (c) Autonomic and sensory nervous system disturbances - pallor, sweating, cold extremities, persistent nausea and intestinal dysfunction, cardiovascular (including neurally mediated hypotension)4 dryncss of mucous membranes especially throat and eyes also extreme sensitivity to pain, myalgia, cephalgia causalgia, and paraesthesiae (d) Other neurological dysfunction includes disturbance of balance, gait and fine motor control, also of pupillary function, taste, smell and hearing.

Deficiencies of neuro-transmitter function including 5HT and dopamine. The encephalopathy and myelopathy can be demonstrated, using PCR, by autopsy and by SPECT scans [5] showing cerebral hypoperfusion as well as by EMG.

2. Musculo-Skeletal problems in some 70% of patients lead to a disabling musculo-tendinous dysfunction with reduced ability to sustain and recover normal muscle energy levels. Clinical features include arthropathy, myalgic foci, muscle spasm, paresis and early acidosis following exercise. The underlying pathological process includes metabolic disturbance due to persistent enteroviral infection or autoimmune attack. Fibromyalgia may have a similar underlying disease process.

3. An Unpredictable State of CNS Exhaustion following minor physical or mental exertion due to underlying brain stem and mid-brain disturbance, including failure of the reticular activating system to maintain wakefulness and attention. This effect, which can be demon­strated by SPECT and PET scan studies may be delayed and require 1-3 days for recovery. It is important to base assessments of the patients' physical capacity on the length and type of these after affects, rather than upon the distanced walked, for example.

4. Extreme Variability of Symptoms Within and Between Episodes

5. Chronic and Protracted Course

A systematic physical examination combined with a comprehensive personal and family history is essential to assess the pre-morbid background, with attention to previous surgery and trauma (especially whiplash) and pre-existing illness (e.g. endocrine, cardiovascular or psychiatric disturbance, all of which may coexist with ME/CFS). Points to note include: facial pallor, BP, pulse, weight, temperature, cognitive ability, visual accommodation, hearing and myalgic foci or fasciculations affecting limbs, shoulder girdle or other muscles, as well as rapid onset of exhaustion.

FBC and ESR (which is invariably low), Electrolytes, thyroid and liver function tests, CPK (if muscle dysfunction is severe), immunological abnormalities are not specific to this illness but estimation of circulating immune complexes or other immunological functions may indicate persistent infection or other causes of disregulation and prove helpful. Viral antibody titres requested within 3 months of onset should include respiratory viruses and an enteroviral IgM. High titres of polio virus or measles antibody are occasionally reported and may indicate a polyclonal response or misdiagnosis between ME/CFS and the post polio syndrome.

No primary therapy is yet available but current research indicates that, if the patient is supported medically, socially and financially to conserve energy, simplify work and reduce stress, a steady decline in health can be halted and the quality of life improved. Once the patient has learnt to adjust activity to their individual sleep/waking cycle and to their energy capacity on any particular day it becomes worth evaluating therapy for residual symptoms.

Patients in this age group suffer more severely from weight loss, sleep reversal, mood and learning disturbances. The diagnosis is often missed, with detrimental results. The doctor in charge should liaise with the school authorities to ensure adequate sick leave, reduce class work and avoid return to school too early with the inevitable exposure to recurrent infection as well as to exam and sports stress. It is better to attempt exams sequentially or to postpone them until a later date to avoid the pupil achieving lower grades than anticipated because of fatigue and stress.

General deleterious factors which are not the cause but may trigger onset or relapse of ME/CFS, include: concurrent infection (especially with influenza, infectious mononucleosis or varicella/zoster); immuno suppression following immunisation, steroids or cytotoxic drugs, ingestion of alcohol or other psychoative agents; hormone imbalance, pregnancy in early stages and post delivery, exposure to neurotoxins, high cholesterol levels; smoking (which also interferes with NK cell function and local mucosal immunity). Individual host factors depend on age, gender, and prior immunising contact with the initial infecting agent in addition to the dose and the potential for inducing serious complications.

Early diagnosis will enable medical, domestic and financial support at a critical stage. Physical or mental stress, including malnutrition, trauma, pre-existing disease, travel, moving house or family bereavement and separation may impede stabilisation and progress. Less than 2% of patients make an early and complete recovery, though many achieve a balance at lowered energy levels. The risk of relapse appears to be life-long but a positive attitude towards future plans together with encouragement to spare energy for pleasurable activities also understanding, kindness and support from relatives, friends and medical attendants, will do much to improve the outlook. Despite high morbidity especially in some 25% of patients who have a persistently downhill course, the mortality rate appears low because death is certified as end organ failure (e.g. cardiac or pancreatic) and suicide.

Those patients are best managed by the primary care physician provided that adequate support is available from community services as well as from specialist referral where diagnostic difficulties present or further investigations are required. It is important not to ascribe all new symptoms to ME/CFS!


1 DOWSETT, E.G. et al
Myalgic Encephalomyelitis - A Persistent Enteroviral Infection?
Post Graduate Medical Journal (1990); 66: 526-530

The Post Polio Syndrome: Advances in the Pathogenesis and Treatment.
in Annals of the New York Academy of Sciences (1995); 273: 1-412
(This symposium reveals the close similarity between ME/CFS and Post Polio)

Evidence for Impaired Activation of the Hypothalamic-Pituitary-Adrenal Axis in Patients with Chronic Fatigue Syndrome
Journal of Clinical Endocrinology and Metabolism (1991); 73 1224-1234, (1991); 73: 1224-1234

Does the Chronic Fatigue Syndrome involve the autonomic nervous system?
American Journal of Medicine (1997); 102:357-364

5 SCHWARTZ, R. B. et al
Detection of Intracranial Abnormalities in Patients with Chronic Fatigue Syndrome - comparison of M.R. imaging with SPECT.
American Journal of Roentgenology (1994); 162: 935-941 See also: 943-951

Long term sickness absence due to ME/CFS in UK schools; An epidemiological study with long term medical and educational implications
Journal of Chronic Fatigue Syndrome (1997); 3(2): 29-42
  (pdf file from Thymes Trust website)

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