Attempts at estimating how may people have ME/CFS/CFIDS have been complicated by the difficulty in defining the condition (due to the lack of a diagnostic marker and the nature and varying degree of symptoms experienced). For example, if 'fatigue' is taken into consideration as one of the symptoms of ME/CFS, how do we define 'fatigue'? In common terms, 'fatigue' is a generally understood term, but when you attempt to define it for research purposes, the term can be unclear, hard to pin down and difficult to use in a research context (Wessely et al., 1998).

Furthermore, attempts to measure the number of ME/CFS sufferers is compounded by the fact that 'fatigue' is a common symptom of many other conditions and studies show that 'fatigue' affects up to half the population. Clearly the debilitating 'fatigue' experienced by most ME/CFS sufferers is very different to the 'normal fatigue' encountered in everyday-life, but nonetheless it makes quantifying the number of sufferers a particularly difficult task. For as Macintyre (1998) states, "clearly, the number of cases of ME/CFS in any community depends on what questions are asked, what criteria are used for diagnosis..." [1]

Nonetheless despite these difficulties, various research studies have tried to estimate how many people are affected by the illness. Studies from a broad variety of countries, including the USA, UK and Australia have produced a wide-range of findings. For instance, in the USA, work carried out by the Centre for Disease Control (CDC) presently calculates that the condition affects a minimum of 4 to 10 adults out of every 100,000 over the age of 18 [2].   In the UK a Royal Colleges' report estimated that the illness was much more common, affecting between 1-2% of the population [3]; and a community survey of 2,376 people indicated a prevalence of 0.5%.[4]  Another study carried out in 1988 in part of New South Wales, Australia found 37 cases per 100,000 were affected.[5]  When all the findings are taken into account, it would seem, according to expert opinion, that the average incidence of ME/CFS is likely to be around 1-2 cases per thousand (Shepherd, 1999; Macintyre, 1998).

 At What Age Does It Normally Start?

ME/CFS can affect all ages, but research carried out seems to point to the onset being most common between 20-40, with a high number reporting an onset in their early thirties (Dowsett and Ramsay, 1990; Hinds, 1993;  Ho-Yen and McNamara, 1991; Shepherd, 1999).

 Is It More Common In Females?

Based on research to date, it would appear that females have a much greater chance of suffering from ME/CFS. When all the published studies are taken into account, it seems that of those suffering from the condition, 60-70% are female. A study carried out by Drs.Dowsett and Ramsay found the ratio between females and males to be 3:1[6]; whereas a study by Dr. Ho-Yen found the ratio be 1.8:1.[7]  Thus women appear to be up to 3 times more likely to get ME/CFS.

 Why Might This Occur?

Dr. Charles Shepherd (1999) has suggested reasons why this might be likely to occur:

• Possibly that it may be harder for women with domestic and family commitments to take time off when they are sick and should be resting.
• That women might be more knowledgeable about ME/CFS due to the publicity it often receives in female publications and consequently they may be more likely to get a diagnosis.
• Mothers and popular female professions, such as teaching and nursing, may be more exposed to infection.
• Possibility of a hormonal link with ME/CFS (Harlow et al. 1996). For instance, according to Dr. Shepherd, women with ME/CFS often experience an improvement in their symptoms during pregnancy - a time of significant hormonal change.[8]

ME/CFS has often been derided in the popular tabloid press as being 'Yuppie Flu' or a disease of the white middle classes, however, the condition affects all social classes, occupations and ethnic groups (Euba et al., 1996; Ho-Yen and McNamara, 1991). Further evidence can be found in a telephone survey of 8,004 households in San Francisco, conducted from a wide-variety of different ethnic and social backgrounds. The survey found that 2 per thousand were affected, and more importantly, that the incidence appeared to be higher in Black and Native Americans, and greater in lower-income groups.[9]  Furthermore, according to Alan McGregor, a professor of medicine, King's College Hospital, London, and a chairman of a scientific advisory panel on ME/CFS, "The idea that this is a disease of so-called yuppies is completely erroneous. This is a disease that can affect anyone. Social background is irrelevant."[10]

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[1] Macintyre, A. (1998) ‘M.E./Chronic Fatigue Syndrome: A Practical Guide’ p. 36.

[2] Shepherd, C. (1999) ‘Living with M.E.’ p.9.

[3] Shepherd, C. (1999) ‘Living with M.E.’ p.9.

[4] Wessely, S., Chalder, T., Hirsch, S. et al. (1997) ‘ The Prevalence and Morbidity of Chronic Fatigue Syndrome: A Prospective Primary Care Study,’ American Journal of Public Health, 87.9: 1455.

[5] Lloyd, A.R., et al. (1990) ‘Prevalence of Chronic Fatigue Syndrome in an Australian population,’ Medical Journal of Australia, 153, p.522-8.

[6] Dowsett, E.G. et al. (1990) ‘Myalgic encephalomyelitis – a persistent enteroviral infection?’ Postgraduate Medical Journal, 66, p.526-30.

[7] Ho-Yen , D.O. and McNamara, I. (1991) ‘General Practitioner’s experience of chronic fatigue syndrome’, British Journal of General Practice, 41, p.324-6. 

[8] Shepherd, C. (1999) ‘Living with M.E.’ p. 29-30.

[9] Macintyre, A. (1998) ‘M.E./Chronic Fatigue Syndrome: A Practical Guide’ p. 35.
SupportMe is an online resource for sufferers of the condition referred to as ME or [10] Hall, Celia (Medical Editor) 'Official: ME does exist' Daily Telegraph, Friday 17 July 1998.