Category: Prevalence

Letter: Time to correct the record on the global burden of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Dear Editor,

We have read Lim et al.’s study [1] with great interest. Studies of this illness are scarce, so their article is important in establishing the global prevalence systematically. In fact, it has been cited over 200 times and has had a significant influence on global reporting of the burden of ME/CFS. Unfortunately, the core figure that is most frequently drawn from the article is a significant underestimate of the prevalence of ME/CFS, and has led to the spread of misinformation about the burden of this disease.

A global ME/CFS population of 17 to 24 million people is reported in articles such as those published in BMC Medicine [2] and Science [3], all referencing Lim et al. The same range of numbers is also easy to find in patient advocacy websites and news reports, such as those of the American Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Society [4] and CNN [5], all updated after Lim et al.’s article was published. However, this figure is drawn from the Background section of Lim et al.’s article, where they state, “In worldwide statistics, approximately 1% of the population, 17 to 24 million people, suffer from this condition [14], which is likely to be as common as rheumatoid arthritis” [1]. The cited reference (reference [14]) is an article about the global burden of multiple sclerosis, and is not relevant to the global ME/CFS population.

The actual headline result of the study by Lim et al. was an estimated prevalence of 0.89% using the CDC-1994 definition, as indicated in the Discussion and Conclusions sections of their article [1]. If we correctly apply this to the global population of 8 billion, the true prevalence of ME/CFS would be 71.2 million (71,200,000). However, new research using more up-to-date datasets and methods is essential to gain a full understanding of the burden of this disease.

Due to this unfortunate misreading and misattribution by others of an erroneous reference in the Background section of Lim et al.’s article, there is widespread underestimation of the true burden of ME/CFS. Such underestimation may exacerbate the isolation, stigmatization, and suffering of people living with this poorly-understood and under-recognized illness. More effort is needed to correct this underestimation globally, develop treatment methods and welfare support, and relieve the burden of ME/CFS. Correct reporting of the true prevalence of this disease is an important first step to addressing the ongoing neglect that its sufferers experience, and this can begin with the correct reporting of Lim et al.’s research.

Source: Vardaman M, Gilmour S. Letter: Time to correct the record on the global burden of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). J Transl Med. 2025 Mar 14;23(1):331. doi: 10.1186/s12967-025-06281-0. PMID: 40087760. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-025-06281-0 (Full text)

Incidence and Prevalence of Post-COVID-19 Myalgic Encephalomyelitis: A Report from the Observational RECOVER-Adult Study

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) may occur after infection. How often people develop ME/CFS after SARS-CoV-2 infection is unknown.

Objective: To determine the incidence and prevalence of post-COVID-19 ME/CFS among adults enrolled in the Researching COVID to Enhance Recovery (RECOVER-Adult) study.

Design, setting, and participants: RECOVER-Adult is a longitudinal observational cohort study conducted across the U.S. We included participants who had a study visit at least 6 months after infection and had no pre-existing ME/CFS, grouped as (1) acute infected, enrolled within 30 days of infection or enrolled as uninfected who became infected (n=4515); (2) post-acute infected, enrolled greater than 30 days after infection (n=7270); and (3) uninfected (1439).

Measurements: Incidence rate and prevalence of post-COVID-19 ME/CFS based on the 2015 Institute of Medicine ME/CFS clinical diagnostic criteria.

Results: The incidence rate of ME/CFS in participants followed from time of SARS-CoV-2 infection was 2.66 (95% CI 2.63-2.70) per 100 person-years while the rate in matched uninfected participants was 0.93 (95% CI 0.91-10.95) per 100 person-years: a hazard ratio of 4.93 (95% CI 3.62-6.71). The proportion of all RECOVER-Adult participants that met criteria for ME/CFS following SARS-CoV-2 infection was 4.5% (531 of 11,785) compared to 0.6% (9 of 1439) in uninfected participants. Post-exertional malaise was the most common ME/CFS symptom in infected participants (24.0%, 2830 of 11,785). Most participants with post-COVID-19 ME/CFS also met RECOVER criteria for long COVID (88.7%, 471 of 531).

Limitations: The ME/CFS clinical diagnostic criteria uses self-reported symptoms. Symptoms can wax and wane.

Conclusion: ME/CFS is a diagnosable sequela that develops at an increased rate following SARS-CoV-2 infection. RECOVER provides an unprecedented opportunity to study post-COVID-19 ME/CFS.

Source: Vernon SD, Zheng T, Do H, Marconi VC, Jason LA, Singer NG, Natelson BH, Sherif ZA, Bonilla HF, Taylor E, Mullington JM, Ashktorab H, Laiyemo AO, Brim H, Patterson TF, Akintonwa TT, Sekar A, Peluso MJ, Maniar N, Bateman L, Horwitz LI, Hess R; NIH Researching COVID to Enhance Recovery (RECOVER) Consortium. Incidence and Prevalence of Post-COVID-19 Myalgic Encephalomyelitis: A Report from the Observational RECOVER-Adult Study. J Gen Intern Med. 2025 Jan 13. doi: 10.1007/s11606-024-09290-9. Epub ahead of print. PMID: 39804551. https://link.springer.com/article/10.1007/s11606-024-09290-9 (Full text)

Impact of COVID-19 on myalgic encephalomyelitis/chronic fatigue syndrome-like illness prevalence: A cross-sectional survey

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) can be triggered by infectious agents including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the impact of the coronavirus disease 2019 (COVID-19) pandemic on ME/CFS prevalence is not well characterized.

Methods: In this population-based cross-sectional study, we enrolled a stratified random sample of 9,825 adult participants in the Kaiser Permanente Northern California (KPNC) integrated health system from July to October 2022 to assess overall ME/CFS-like illness prevalence and the proportion that were identified following COVID-19 illness. We used medical record and survey data to estimate the prevalence of ME/CFS-like illness based on self-reported symptoms congruent with the 2015 Institute of Medicine ME/CFS criteria. History of COVID-19 was based on a positive SARS-CoV-2 nucleic acid amplification test or ICD-10 diagnosis code in the medical record, or self-report of prior COVID-19 on a survey.

Results: Of 2,745,374 adults in the eligible population, an estimated 45,892 (95% confidence interval [CI]: 32,869, 58,914) or 1.67% (CI 1.20%, 2.15%) had ME/CFS-like illness. Among those with ME/CFS-like illness, an estimated 14.12% (CI 3.64%, 24.6%) developed the illness after COVID-19. Among persons who had COVID-19, those with ME/CFS-like illness after COVID-19 were more likely to be unvaccinated and to have had COVID-19 before June 1, 2021. All persons with ME/CFS-like illness had significant impairment in physical, mental, emotional, social, and occupational functioning compared to persons without ME/CFS-like illness.

Conclusions: In a large, integrated health system, 1.67% of adults had ME/CFS-like illness and 14.12% of all persons with ME/CFS-like illness developed it after COVID-19. Though COVID-19 did not substantially increase ME/CFS-like illness in the KPNC population during the study time period, ME/CFS-like illness nevertheless affects a notable portion of this population and is consistent with estimates of ME/CFS prevalence in other populations. Additional attention is needed to improve awareness, diagnosis, and treatment of ME/CFS.

Source: Wood MS, Halmer N, Bertolli J, Amsden LB, Nugent JR, Lin JS, Rothrock G, Nadle J, Chai SJ, Cope JR, Champsi JH, Yang J, Unger ER, Skarbinski J; for STOP-ME/CFS and COVID-SELECT. Impact of COVID-19 on myalgic encephalomyelitis/chronic fatigue syndrome-like illness prevalence: A cross-sectional survey. PLoS One. 2024 Sep 18;19(9):e0309810. doi: 10.1371/journal.pone.0309810. PMID: 39292671; PMCID: PMC11410243. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11410243/ (Full text)

Chronic fatigue syndrome: number of patients is expected to double due to long-term effects of the COVID-19 pandemic

Press Release:

Up to 80,000 people in Austria are estimated to suffer from chronic fatigue syndrome, also known as ME/CFS or myalgic encephalomyelitis/chronic fatigue syndrome. The number of ME/CFS patients is expected to rise drastically due to long-term effects of the COVID-19 pandemic. However, research in the field has neither identified mechanisms of disease onset nor causal treatment approaches. Scientists at MedUni Vienna have now identified possible biomarkers that could improve the diagnosis and treatment of long-lasting and debilitating fatigue. The study has recently been published in the Journal of Clinical Medicine.

The study by Eva Untersmayr-Elsenhuber and her team from MedUni Vienna’s Center for Pathophysiology, Infectiology and Immunology builds on earlier research on immune disorders and the intestinal barrier function in patients with ME/CFS. It is well known that ME/CFS patients often differ greatly in the clinical manifestations of their disease. However, despite intensive research, there is still no measurable parameter (biomarker) that clearly indicates the disease.

As the MedUni Vienna research team shows, ME/CFS patients can be divided into subgroups based on the function of their immune system. The study was able to identify various biomarkers in the patients that indicate immune system disorders or reduced intestinal barrier function. As a result, differences relevant to clinical care were identified in ME/CFS patients that would have remained undetected without the previous immunological stratification of the ME/CFS patient group. “In our study, we see that the immunological evaluation of ME/CFS patients is of crucial importance. Patients suffering from immunodeficiencies are characterised by an altered innate immune function. In ME/CFS patients with an intact immune system, the intestinal barrier function was reduced,” explains the study’s principal investigator Eva Untersmayr-Elsenhuber. According to the researchers, this not only provides a more detailed insight in different disease mechanisms, but also indicates that depending on the patient’s immune competence, some treatment approaches might be more suitable than others.

The next step will be to review the study results on a larger scale. In order to advance research in the field, the first ME/CFS Biobank in Austria is currently being set up at MedUni Vienna with the support of the WE&ME Foundation. “ME/CFS Biobank Austria” collects human samples, which will be made available for future research projects. Untersmayr-Elsenhuber: “To ensure that ME/CFS research can take place quickly and transnationally in the future, we have been coordinating with research groups in the UK, the Netherlands and Germany from the outset.”

25 per cent of those affected are bedridden

ME/CFS is a severe multisystemic disease that often leads to a high degree of disability. 60 per cent of patients are unable to work full-time and 25 per cent are bedridden. The exact causes of the disease are still unclear. As diagnosis is difficult due to the lack of biomarkers, the number of people affected cannot be precisely quantified. According to current studies, between 26,000 and 80,000 people in Austria suffer from chronic fatigue. Due to Covid-19, this number could double in the next few years. The links between infection with SARS-CoV-2 and ME/CFS are also the subject of intensive research.

JOURNAL

Journal of Clinical Medicine

DOI

10.3390/jcm13010275 

ARTICLE TITLE

Immunological Patient Stratification in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

ARTICLE PUBLICATION DATE

3-Jan-2024

The importance of estimating prevalence of ME/CFS in future epidemiological studies of long COVID

Abstract:

The resolution of the COVID-19 pandemic is giving rise to another public health challenge due to the explosion of long COVID (LC) cases. In many cases, LC results in persistent fatigue, post-exertional malaise (PEM), and other debilitating symptoms that resemble the clinical manifestation of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The similarity of these two diseases suggests that future epidemiological studies of LC could take the opportunity to also estimate the prevalence of ME/CFS at a minimal cost.

With this opportunity in mind, we revisited the most consensual case definitions of ME/CFS for research purposes. We then compared the symptoms assessed at the participants’ enrollment in the UK ME/CFS Biobank with those documented in three systematic reviews encompassing hundreds of LC epidemiological studies. We found that published epidemiological studies of LC did not consistently assess or report the prevalence of PEM, which is a compulsory symptom for ME/CFS diagnosis. However, these studies assessed many neuro-cognitive, immunologic, and autonomic symptoms.

In this scenario, we recommend that the estimation of ME/CFS prevalence in the context of LC epidemiology is easily achievable by deploying tested and validated diagnosis tools used in ME/CFS. The knowledge of ME/CFS prevalence within the LC population is of cardinal importance to optimal allocation of resources and better design of healthcare interventions to manage and treat patients with this devastating disease.

Source: Anna D. Grabowska, Francisco Westermeier, Luís Nacul, Eliana Lacerda, Nuno Sepúlveda. The importance of estimating prevalence of ME/CFS in future epidemiological studies of long COVID. DOI:10.13140/RG.2.2.20997.52967 https://www.researchgate.net/publication/373043778_The_importance_of_estimating_prevalence_of_MECFS_in_future_epidemiological_studies_of_long_COVID (Full text)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and COVID-19: is there a connection?

Abstract:

Objectives: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic systemic disease that leads to neurological, immunological, autonomic, and energy metabolism dysfunction. COVID-19 has been reported to cause similar symptoms to ME/CFS. The study aims to investigate the prevalence of myalgic encephalomyelitis in patients post-COVID-19 infection by assessing acute and long-term COVID-19 symptoms.

Methods: A cross-sectional questionnaire was developed based on the ME/CFS diagnostic criteria, as specified by the IOM clinical diagnostic criteria, and administered to participants with confirmed COVID-19 who are more than 18 years old and have BMI below 40 Kg/m2. Data from 437 participants were completed.

Results: The current study results revealed that 8.1% of the study participants met the ME/CFS diagnostic criteria. Interestingly, 2.8 of the study participants were classified to have COVID-19 related to ME/CFS. While 4.6% of participants were determined to have disease-related fatigue, 0.7% of participants showed ME/CFS that was not related to COVID-19, and 3.7% of participants were considered to have long COVID-19. Almost one-fourth of the study participants had a family history of ME/CFS. The current study demonstrated that the prevalence of ME/CFS is similar to slightly higher than reported in the literature.

Conclusion: The presence of a relationship between ME/CFS and COVID-19 has been supported by the results of our study. Follow-up of COVID-19 patients is strongly recommended to ensure proper management of ME/CFS symptoms.

Source: Muhaissen SA, Abu Libdeh A, ElKhatib Y, Alshayeb R, Jaara A, Bardaweel SK. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and COVID-19: is there a connection? Curr Med Res Opin. 2023 Jul 28:1-24. doi: 10.1080/03007995.2023.2242244. Epub ahead of print. PMID: 37501626. https://pubmed.ncbi.nlm.nih.gov/37501626/

ME/CFS and Post-Exertional Malaise among Patients with Long COVID

Abstract:

This study sought to ascertain the prevalence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) among a sample of 465 patients with Long COVID. The participants completed three questionnaires: (1) a new questionnaire measuring both the frequency and severity of 38 common symptoms of COVID and Long COVID, (2) a validated short form questionnaire assessing ME/CFS, and (3) a validated questionnaire measuring post-exertional malaise.
The population was predominantly white, female, and living in North America. The mean duration since the onset of COVID-19 symptoms was 70.5 weeks. Among the 465 participants, 58% met a ME/CFS case definition. Of respondents who reported that they had ME/CFS only 70.57% met criteria for ME/CFS and of those who did not report they had ME/CFS, 29.43% nevertheless did meet criteria for the disease: both over-diagnosis and under-diagnosis were evident on self-report. This study supports prior findings that ME/CFS occurs with high prevalence among those who have persistent COVID-19 symptoms.
Source: Jason LA, Dorri JA. ME/CFS and Post-Exertional Malaise among Patients with Long COVID. Neurology International. 2023; 15(1):1-11. https://doi.org/10.3390/neurolint15010001 https://www.mdpi.com/2035-8377/15/1/1 (Full text)

Severe myalgic encephalomyelitis/chronic fatigue syndrome in children and young people: a British Paediatric Surveillance Unit study

Abstract:

Objectives: Primary objective: to determine the point prevalence and incidence rate of severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in children aged 5-16 years over 13 months.

Secondary objectives: to describe the demographic features, symptoms, impact on activities of daily living, school attendance and time to diagnosis.

Design: Prospective surveillance study conducted by the British Paediatric Surveillance Unit. Paediatricians was asked if they had assessed a child with severe ME/CFS (screening definition for prevalence and incidence: children (5-16 years) diagnosed with ME/CFS so severe that they are unable to attend school for more than 1 hour a week during the last 6 weeks of the school term).

Participants: Patients 5-16 years of age, seen by paediatricians and two large ME/CFS specialist services across the UK and Ireland.

Outcome measures: Paediatrician-completed questionnaires describing demographics, symptoms, function and treatment, (applying National Institute for Health and Care Excellence (NICE)-recommended criteria to assess severity of ME/CFS). Diagnosis of severe, probable severe or possible severe ME/CFS was made only with evidence of NICE-recommended screening blood tests.

Results: 285 cases were reported, of which of which 33 were severe, 4 probable severe and 55 possible severe. Estimated prevalence was 3.2 per million children (95% CI 2.2 to 4.5). Including possible/probable severe ME/CFS gave 8.9 per million children (95% CI 7.2 to 11). The incidence rate was 0.90 per million children-years (95% CI 0.43 to 1.65) (1.97 per million children-years (95% CI 1.24 to 2.99)). Median age was 13 years and 58% of cases were female. Median time to diagnosis was 0.47 years.

Conclusions: Although the incidence of children presenting with severe ME/CFS is low, all were very disabled. In addition, the majority receive little or no education. Paediatricians need to consider how to provide rehabilitation and education for these disabled young people.

Source: Royston AP, Rai M, Brigden A, Burge S, Segal TY, Crawley EM. Severe myalgic encephalomyelitis/chronic fatigue syndrome in children and young people: a British Paediatric Surveillance Unit study. Arch Dis Child. 2022 Dec 1:archdischild-2022-324319. doi: 10.1136/archdischild-2022-324319. Epub ahead of print. PMID: 36456114. https://adc.bmj.com/content/early/2022/11/30/archdischild-2022-324319 (Full text)

Global prevalence of chronic fatigue syndrome among long COVID-19 patients: A systematic review and meta-analysis

Abstract:

Background: Chronic fatigue syndrome is a persistent and debilitating disorder. According to several studies, chronic fatigue syndrome has been identified among recovered COVID-19 patients as the most common symptom of long COVID. The aim of this systematic review and meta-analysis study was to obtain the prevalence of chronic fatigue syndrome in long COVID cases.

Methods: In this systematic review and meta-analysis, we analysed reported results of studies that assessed the occurrence of chronic fatigue syndrome among COVID-19 patients four weeks after the onset of symptoms. The study selection was commenced by searching PubMed, Web of Science, Science Direct, Scopus, Embase, and Google scholar using the keywords of Chronic fatigue syndrome, COVID-19, and post-COVID-19 syndrome. The searches were without a lower time limit and until April 2022. Heterogeneity of studies was assessed using the I2 index, and a random effects model was used for analysis. Data analysis was performed within the Comprehensive Meta-Analysis software (version 2).

Results: The pooled prevalence of chronic fatigue syndrome four weeks after the onset of COVID-19 symptoms, in 52 studies with a sample size of 127,117, was 45.2% (95% CI: 34.1-56.9%). Meta-regression analysis in examining the effects of the two factors of sample size, and year of study on the changes in the overall prevalence, showed that with increasing sample size, and year of study, the prevalence of chronic fatigue syndrome among long COVID patients (p < 0.05).

Conclusion: Our results show that the overall prevalence of chronic fatigue syndrome as a long COVID symptom is 45.2%. Chronic fatigue after infection with COVID-19 can negatively affect personal and social lives. Given such significant negative consequences caused by the syndrome, it is recommended that health policymakers allocate funds to reduce the adverse effects of this syndrome, by creating programs to support long COVID patients.

Source: Salari N, Khodayari Y, Hosseinian-Far A, Zarei H, Rasoulpoor S, Akbari H, Mohammadi M. Global prevalence of chronic fatigue syndrome among long COVID-19 patients: A systematic review and meta-analysis. Biopsychosoc Med. 2022 Oct 23;16(1):21. doi: 10.1186/s13030-022-00250-5. PMID: 36274177; PMCID: PMC9589726. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9589726/ (Full text)

Prevalence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in Australian primary care patients: only part of the story?

Abstract:

Background: ME/CFS is a disorder characterized by recurrent fatigue and intolerance to exertion which manifests as profound post-exertional malaise. Prevalence studies internationally have reported highly variable results due to the 20 + diagnostic criteria. For Australia, the prevalence of ME/CFS based on current case definitions is unknown.

Objectives: To report prevalence of ME/CFS in patients aged ≥ 13 years attending Australian primary care settings for years 2015-2019, and provide context for patterns of primary care attendance by people living with ME/CFS.

Methodology: Conducted in partnership with the Patient Advisory Group, this study adopted a mixed methods approach. De-identified primary care data from the national MedicineInsight program were analyzed. The cohort were regularly attending patients, i.e. 3 visits in the preceding 2 years. Crude prevalence rates were calculated for years 2015-2019, by sex, 10-year age groups, remoteness and socioeconomic status. Rates are presented per 100,000population (95% confidence intervals (CI)). Qualitative data was collected through focus groups and in-depth 1:1 interview.

Results: Qualitative evidence identified barriers to reaching diagnosis, and limited interactions with primary care due to a lack of available treatments/interventions, stigma and disbelief in ME/CFS as a condition. In each year of interest, crude prevalence in the primary care setting ranged between 94.9/100,000 (95% CI: 91.5-98.5) and 103.9/100,000 population (95%CI: 100.3-107.7), equating to between 20,140 and 22,050 people living with ME/CFS in Australia in 2020. Higher rates were observed for age groups 50-59 years and 40-49 years. Rates were substantially higher in females (130.0-141.4/100,000) compared to males (50.9-57.5/100,000). In the context of the qualitative evidence, our prevalence rates likely represent an underestimate of the true prevalence of ME/CFS in the Australian primary care setting.

Conclusion: ME/CFS affects a substantial number of Australians. Whilst this study provides prevalence estimates for the Australian primary care setting, the qualitative evidence highlights the limitations of these. Future research should focus on using robust case ascertainment criteria in a community setting. Quantification of the burden of disease can be used to inform health policy and planning, for this understudied condition.

Source: Orji N, Campbell JA, Wills K, Hensher M, Palmer AJ, Rogerson M, Kelly R, de Graaff B. Prevalence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in Australian primary care patients: only part of the story? BMC Public Health. 2022 Aug 9;22(1):1516. doi: 10.1186/s12889-022-13929-9. PMID: 35945527. https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-022-13929-9 (Full text)