Chronic fatigue syndromes: relationship to chronic viral infections

Health Controversies: Long-Term Disagreement Management Challenges

Health controversies involve complex exchanges of disagreements over health and medicine. They unfold differently in different parts of the world, and they often extend over long periods of time. In contemporary argumentation theory, proposals have recently been emerging for "disagreement management at large scale" and for an explicit focus on design of disagreement management methods. Lewiński and Aakhus characterize large-scale disagreement as polylogic: formed of complex networks of players holding contrasting positions that are attacked and defended in multiple places. Large-scale disagreements such as health controversies are important sites for emergence of new disagreement management methods, including new ways of arriving at conclusions about questions of fact (affecting positions) and new formats for coming to decisions about questions of policy (affecting places). The controversy over myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), spanning a period of very rapid change in reasoning about health, has been deeply entangled with the design of new institutional places for managing disagreements about health. It serves well to illustrate both the large, multi-scale structure of health controversies and the importance of long-term disagreement management strategies.

From Viral Infection to Autoimmune Reaction: Exploring the Link between Human Herpesvirus 6 and Autoimmune Diseases

The complexity of autoimmunity initiation has been the subject of many studies. Both genetic and environmental factors are essential in autoimmunity development. Among others, environmental factors include infectious agents. HHV-6 is a ubiquitous human pathogen with a high global prevalence. It has several properties suggestive of its contribution to autoimmunity development. HHV-6 has a broad cell tropism, the ability to establish latency with subsequent reactivation and persistence, and a range of immunomodulation capabilities. Studies have implicated HHV-6 in a plethora of autoimmune diseases-endocrine, neurological, connective tissue, and others-with some studies even proposing possible autoimmunity induction mechanisms. HHV-6 can be frequently found in autoimmunity-affected tissues and lesions; it has been found to infect autoimmune-pathology-relevant cells and influence immune responses and signaling. This review highlights some of the most well-known autoimmune conditions to which HHV-6 has been linked, like multiple sclerosis and autoimmune thyroiditis, and summarizes the data on HHV-6 involvement in autoimmunity development.

One-year follow-up of young people with ME/CFS following infectious mononucleosis by Epstein-Barr virus

Background

Infectious mononucleosis after primary infection with Epstein-Barr virus (EBV-IM) has been linked to the development of myalgic encephalomyelitis/chronic fatigue-syndrome (ME/CFS) in children, adolescents, and young adults. Here, we present clinical phenotypes and follow-up data from a first German cohort of young people with ME/CFS following EBV-IM.

Methods

12 adolescents and 13 young adults were diagnosed with IM-triggered ME/CFS at our specialized tertiary outpatient service by clinical criteria requiring post-exertional malaise (PEM) and a history of confirmed EBV primary infection as triggering event. Demographic information, laboratory findings, frequency and severity of symptoms, physical functioning, and health-related quality of life (HRQoL) were assessed and re-evaluated 6 and 12 months later.

Results

Young adults displayed more severe symptoms as well as worsening of fatigue, physical and mental functioning, and HRQoL throughout the study, compared to adolescents. After one year, 6/12 (54%) adolescents no longer met the diagnostic criteria for ME/CFS while all young adults continued to fulfill the Canadian consensus criteria. Improvement in adolescents was evident in physical functioning, symptom frequency and severity, and HRQoL, while young adults showed little improvement. EBV serology and EBV DNA load did not correlate with distinct clinical features of ME/CFS, and clinical chemistry showed no evidence of inflammation. Remarkably, the median time from symptom onset to ME/CFS diagnosis was 13.8 (IQR: 9.1-34.9) months.

Conclusions

ME/CFS following EBV-IM is a severely debilitating disease often diagnosed late and with limited responses to conventional medical care, especially in adults. Although adolescents may have a better prognosis, their condition can fluctuate and significantly impact their HRQoL. Our data emphasize that biomarkers and effective therapeutic options are also urgently needed to improve medical care and pave the way to recovery.

Epstein-Barr virus-acquired immunodeficiency in myalgic encephalomyelitis-Is it present in long COVID?

Both myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) and long COVID (LC) are characterized by similar immunological alterations, persistence of chronic viral infection, autoimmunity, chronic inflammatory state, viral reactivation, hypocortisolism, and microclot formation. They also present with similar symptoms such as asthenia, exercise intolerance, sleep disorders, cognitive dysfunction, and neurological and gastrointestinal complaints. In addition, both pathologies present Epstein-Barr virus (EBV) reactivation, indicating the possibility of this virus being the link between both pathologies. Therefore, we propose that latency and recurrent EBV reactivation could generate an acquired immunodeficiency syndrome in three steps: first, an acquired EBV immunodeficiency develops in individuals with "weak" EBV HLA-II haplotypes, which prevents the control of latency I cells. Second, ectopic lymphoid structures with EBV latency form in different tissues (including the CNS), promoting inflammatory responses and further impairment of cell-mediated immunity. Finally, immune exhaustion occurs due to chronic exposure to viral antigens, with consolidation of the disease. In the case of LC, prior to the first step, there is the possibility of previous SARS-CoV-2 infection in individuals with "weak" HLA-II haplotypes against this virus and/or EBV.

At the Root of 3 “Long” Diseases: Persistent Antigens Inflicting Chronic Damage on the Brain and Other Organs in Gulf War Illness, Long-COVID-19, and Chronic Fatigue Syndrome

Several foreign antigens such as those derived from viruses and bacteria have been linked to long-term deleterious effects on the brain and other organs; yet, health outcomes subsequent to foreign antigen exposure vary depending in large part on the host’s immune system, in general, and on human leukocyte antigen (HLA) composition, in particular. Here we first provide a brief description of 3 conditions characterized by persistent long-term symptoms, namely long-COVID-19, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and Gulf War Illness (GWI), followed by a brief overview of the role of HLA in the immune response to foreign antigens. We then discuss our Persistent Antigen (PA) hypothesis and highlight associations between antigen persistence due to HLA-antigen incongruence and chronic health conditions in general and the 3 “long” diseases above in particular. This review is not intended to cover the breadth and depth of symptomatology of those diseases but is specifically focused on the hypothesis that the presence of persistent antigens underlies their pathogenesis.

Salivary DNA Loads for Human Herpesviruses 6 and 7 Are Correlated With Disease Phenotype in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex chronic condition affecting multiple body systems, with unknown cause, unclear pathogenesis mechanisms, and fluctuating symptoms which may lead to severe debilitation. It is frequently reported to have been triggered by an infection, but there are no clear differences in exposure to, or seroprevalence of, any particular viruses between people with ME/CFS and healthy individuals. However, herpes viruses have been repeatedly hypothesized to underlie the chronic relapsing/remitting form of MS/CFS due to their persistence in a latent form with periodic reactivation. It is possible that ME/CFS is associated with herpes virus reactivation, which has not been detectable previously due to insufficiently sensitive testing methods. Saliva samples were collected from 30 people living with ME/CFS at monthly intervals for 6 months and at times when they experienced symptom exacerbation, as well as from 14 healthy control individuals. The viral DNA load of the nine humanherpes viruses was determined by digital droplet PCR. Symptoms were assessed by questionnaire at each time point. Human herpesvirus (HHV) 6B, HHV-7, herpes simplex virus 1 and Epstein-Barr virus were detectable within the saliva samples, with higher HHV-6B and HHV-7 viral loads detected in people with ME/CFS than in healthy controls. Participants with ME/CFS could be broadly separated into two groups: one group displayed fluctuating patterns of herpesviruses detectable across the 6 months while the second group displayed more stable viral presentation. In the first group, there was positive correlation between HHV-6B and HHV-7 viral load and severity of symptom scores, including pain, neurocognition, and autonomic dysfunction. The results indicate that fluctuating viral DNA load correlates with ME/CFS symptoms: this is in accordance with the hypothesis that pathogenesis is related to herpesvirus reactivation state, and this should be formally tested. Herpesvirus reactivation might be a cause or consequence of dysregulated immune function seen in ME/CFS. The sampling strategy and molecular tools developed here permit such large-scale epidemiological investigations.

Human Herpesvirus 6 Infection and Risk of Chronic Fatigue Syndrome: A Systematic Review and Meta-Analysis

INTRODUCTION

Chronic fatigue syndrome (CFS) is a neurological disease that is accompanied by excessive fatigue or tiredness. There are several reports confirming the association between human herpesvirus 6 (HHV-6) infection and CFS illness. This systematic review and meta-analysis was performed to integrate the information of published studies with regard to this association until May 2021.

METHODS

The literature search was based on keywords including "chronic fatigue syndrome and HHV 6," "chronic fatigue syndrome and HHV-6," "chronic fatigue syndrome and HHV6," "chronic fatigue syndrome and Herpes virus 6," and "chronic fatigue syndrome and Herpesvirus6" in MEDLINE (PubMed), Web of Science, and EMBASE.

RESULTS

The literature search identified 17 studies to be included in the systematic review and 11 studies in meta-analysis. The symmetry funnel plot and Egger's test (p value = 0.2) identified no publication bias among studies. Moreover, the low level of I2 revealed homogeneity across studies.

DISCUSSION

In conclusion, the association between the HHV-6 infection and CFS incidence was substantiated. However, the results of this study also suggest that further comprehensive studies are needed to solidify the association between HHV-6 and CFS. Future studies should consider additional factors that may have affected the significance of such a correlation.

Ross River Virus Immune Evasion Strategies and the Relevance to Post-viral Fatigue, and Myalgic Encephalomyelitis Onset

Ross River virus (RRV) is an endemic Australian arbovirus, and member of the Alphavirus family that also includes Chikungunya virus (CHIK). RRV is responsible for the highest prevalence of human disease cases associated with mosquito-borne transmission in Australia, and has long been a leading suspect in cases of post-viral fatigue syndromes, with extrapolation of this link to Myalgic Encephalomyelitis (ME). Research into RRV pathogenesis has revealed a number of immune evasion strategies, impressive for a virus with a genome size of 12 kb (plus strand RNA), which resonate with insights into viral pathogenesis broadly. Drawing from observations on RRV immune evasion, mechanisms of relevance to long term idiopathic fatigue are featured as a perspective on infection and eventual ME symptoms, which include considerations of; (1) selective pro-inflammatory gene suppression post antibody-dependent enhancement (ADE) of RRV infection, (2) Evidence from other virus families of immune disruption and evasion post-ADE, and (3) how virally-driven immune evasion may impact on mitochondrial function via target of rapamycin (TOR) complexes. In light of these RRV measures to counter the host immune - inflammatory responses, links to recent discoveries explaining cellular, immune and metabolomic markers of ME will be explored and discussed, with the implications for long-COVID post SARS-CoV-2 also considered. Compelling issues on the connections between virally-induced alterations in cytokine expression, for example, will be of particular interest in light of energy pathways, and how these perturbations manifest clinically.

Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Background and main text

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and controversial clinical condition without having established causative factors. Increasing numbers of cases during past decade have created awareness among patients as well as healthcare professionals. Chronic viral infection as a cause of ME/CFS has long been debated. However, lack of large studies involving well-designed patient groups and validated experimental set ups have hindered our knowledge about this disease. Moreover, recent developments regarding molecular mechanism of pathogenesis of various infectious agents cast doubts over validity of several of the past studies.

Conclusions

This review aims to compile all the studies done so far to investigate various viral agents that could be associated with ME/CFS. Furthermore, we suggest strategies to better design future studies on the role of viral infections in ME/CFS.

Subtyping Patients with Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) By Course of Illness

Past research has subtyped patients with Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) according to factors related to illness onset, illness duration, and age. However, no classification system fully accounts for the wide range of symptom severity, functional disability, progression, and prognosis seen among patients. This study examined whether illness trajectories among individuals with CFS were predictive of different levels of symptomology, functional disability, and energy expenditure. Of the participants (N=541), the majority described their illness as Fluctuating (59.7%), with 15.9% Constantly Getting Worse, 14.1% Persisting, 8.5% Relapsing and Remitting, and 1.9% Constantly Getting Better. The illness courses were associated with significant differences in symptomology on select domains of the DSQ, functioning on select subscales of the SF-36, and on overall levels of energy expenditure. The significant symptomatic and functional differences between groups suggest that subtyping patients with CFS according to illness course is a promising method for creating more homogeneous groups of patients.

Sleep and Microbes

Sleep is profoundly altered during the course of infectious diseases. The typical response to infection includes an initial increase in nonrapid eye movement sleep (NREMS) followed by an inhibition in NREMS. REMS is inhibited during infections. Bacterial cell wall components, such as peptidoglycan and lipopolysaccharide, macrophage digests of these components, such as muramyl peptides, and viral products, such as viral double-stranded RNA, trigger sleep responses. They do so via pathogen-associated molecular pattern recognition receptors that, in turn, enhance cytokine production. Altered sleep and associated sleep-facilitated fever responses are likely adaptive responses to infection. Normal sleep in physiological conditions may also be influenced by gut microbes because the microbiota is affected by circadian rhythms, stressors, diet, and exercise. Furthermore, sleep loss enhances translocation of viable bacteria from the intestine, which provides another means by which sleep-microbe interactions impact neurobiology.

The aetiopathogenesis of fatigue: unpredictable, complex and persistent

BACKGROUND

Chronic fatigue syndrome is a common condition characterized by severe fatigue with post-exertional malaise, impaired cognitive ability, poor sleep quality, muscle pain, multi-joint pain, tender lymph nodes, sore throat or headache. Its defining symptom, fatigue is common to several diseases.

AREAS OF AGREEMENT

Research has established a broad picture of impairment across autonomic, endocrine and inflammatory systems though progress seems to have reached an impasse.

AREAS OF CONTROVERSY

The absence of a clear consensus view of the pathophysiology of fatigue suggests the need to switch from a focus on abnormalities in one system to an experimental and clinical approach which integrates findings across multiple systems and their constituent parts and to consider multiple environmental factors.

GROWING POINTS

We discuss this with reference to three key factors, non-determinism, non-reductionism and self-organization and suggest that an approach based on these principles may afford a coherent explanatory framework for much of the observed phenomena in fatigue and offers promising avenues for future research.

AREAS TIMELY FOR DEVELOPING RESEARCH

By adopting this approach, the field can examine issues regarding aetiopathogenesis and treatment, with relevance for future research and clinical practice.

The status of and future research into Myalgic Encephalomyelitis and Chronic Fatigue Syndrome: the need of accurate diagnosis, objective assessment, and acknowledging biological and clinical subgroups

Although Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) are used interchangeably, the diagnostic criteria define two distinct clinical entities. Cognitive impairment, (muscle) weakness, circulatory disturbances, marked variability of symptoms, and, above all, post-exertional malaise: a long-lasting increase of symptoms after a minor exertion, are distinctive symptoms of ME. This latter phenomenon separates ME, a neuro-immune illness, from chronic fatigue (syndrome), other disorders and deconditioning. The introduction of the label, but more importantly the diagnostic criteria for CFS have generated much confusion, mostly because chronic fatigue is a subjective and ambiguous notion. CFS was redefined in 1994 into unexplained (persistent or relapsing) chronic fatigue, accompanied by at least four out of eight symptoms, e.g., headaches and unrefreshing sleep. Most of the research into ME and/or CFS in the last decades was based upon the multivalent CFS criteria, which define a heterogeneous patient group. Due to the fact that fatigue and other symptoms are non-discriminative, subjective experiences, research has been hampered. Various authors have questioned the physiological nature of the symptoms and qualified ME/CFS as somatization. However, various typical symptoms can be assessed objectively using standardized methods. Despite subjective and unclear criteria and measures, research has observed specific abnormalities in ME/CFS repetitively, e.g., immunological abnormalities, oxidative and nitrosative stress, neurological anomalies, circulatory deficits and mitochondrial dysfunction. However, to improve future research standards and patient care, it is crucial that patients with post-exertional malaise (ME) and patients without this odd phenomenon are acknowledged as separate clinical entities that the diagnosis of ME and CFS in research and clinical practice is based upon accurate criteria and an objective assessment of characteristic symptoms, as much as possible that well-defined clinical and biological subgroups of ME and CFS patients are investigated in more detail, and that patients are monitored before, during and after interventions with objective measures and biomarkers.

Case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME): a systematic review

OBJECTIVE

To identify case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), and explore how the validity of case definitions can be evaluated in the absence of a reference standard.

DESIGN

Systematic review.

SETTING

International.

PARTICIPANTS

A literature search, updated as of November 2013, led to the identification of 20 case definitions and inclusion of 38 validation studies.

PRIMARY AND SECONDARY OUTCOME MEASURE

Validation studies were assessed for risk of bias and categorised according to three validation models: (1) independent application of several case definitions on the same population, (2) sequential application of different case definitions on patients diagnosed with CFS/ME with one set of diagnostic criteria or (3) comparison of prevalence estimates from different case definitions applied on different populations.

RESULTS

A total of 38 studies contributed data of sufficient quality and consistency for evaluation of validity, with CDC-1994/Fukuda as the most frequently applied case definition. No study rigorously assessed the reproducibility or feasibility of case definitions. Validation studies were small with methodological weaknesses and inconsistent results. No empirical data indicated that any case definition specifically identified patients with a neuroimmunological condition.

CONCLUSIONS

Classification of patients according to severity and symptom patterns, aiming to predict prognosis or effectiveness of therapy, seems useful. Development of further case definitions of CFS/ME should be given a low priority. Consistency in research can be achieved by applying diagnostic criteria that have been subjected to systematic evaluation.

Response to valganciclovir in chronic fatigue syndrome patients with human herpesvirus 6 and Epstein-Barr virus IgG antibody titers

Valganciclovir has been reported to improve physical and cognitive symptoms in patients with chronic fatigue syndrome (CFS) with elevated human herpesvirus 6 (HHV-6) and Epstein-Barr virus (EBV) IgG antibody titers. This study investigated whether antibody titers against HHV-6 and EBV were associated with clinical response to valganciclovir in a subset of CFS patients. An uncontrolled, unblinded retrospective chart review was performed on 61 CFS patients treated with 900 mg valganciclovir daily (55 of whom took an induction dose of 1,800 mg daily for the first 3 weeks). Antibody titers were considered high if HHV-6 IgG ≥ 1:320, EBV viral capsid antigen (VCA) IgG ≥ 1:640, and EBV early antigen (EA) IgG ≥ 1:160. Patients self-rated physical and cognitive functioning as a percentage of their functioning prior to illness. Patients were categorized as responders if they experienced at least 30% improvement in physical and/or cognitive functioning. Thirty-two patients (52%) were categorized as responders. Among these, 19 patients (59%) responded physically and 26 patients (81%) responded cognitively. Baseline antibody titers showed no significant association with response. After treatment, the average change in physical and cognitive functioning levels for all patients was +19% and +23%, respectively (P < 0.0001). Longer treatment was associated with improved response (P = 0.0002). No significant difference was found between responders and non-responders among other variables analyzed. Valganciclovir treatment, independent of the baseline antibody titers, was associated with self-rated improvement in physical and cognitive functioning for CFS patients who had positive HHV-6 and/or EBV serologies. Longer valganciclovir treatment correlated with an improved response.

Herpesvirus serology, aberrant specific immunoglobulin G2 and G3 subclass patterns and Gm allotypes in individuals with low levels of IgG3

One objective of this study was to determine whether IgG3-deficient individuals have an increased frequency of reactivated herpesvirus infections. Serum titres to Epstein-Barr virus (EBV) and human herpesvirus-6 were examined in 10 healthy and in 10 symptomatic persons with serum IgG3 &lt; 0·1 g/l. Atypical titres were found in 16% of the IgG3-deficient individuals. Reactivations of these viruses thus do not seem common in IgG3 deficiency. Antigen-specific IgG responses were also determined. A lowered frequency of IgG3 to an EBV-derived peptide was found only in symptomatic, IgG3-deficient individuals. Levels of IgG2 to a bacterial polysaccharide were lowered in the same group, despite normal serum levels of total IgG2. A functional IgG2 deficiency may contribute to symptoms in IgG3 deficiency. The G3(g) allotype, known to be associated with low total IgG3, dominated in IgG3-deficient persons (13/17) independently of presence or absence of symptoms. A linkage of G3(g) to the G2(n) negative allotype, associated with low IgG2, was equally common irrespective of symptoms. G3(g) and absence of G2(n) seem to be one prerequisite for most of IgG3 deficiency combined with low specific IgG2.

β-Alanine and γ-aminobutyric acid in chronic fatigue syndrome

BACKGROUND

Due to the occurrence of sleep disturbances and fatigue in chronic fatigue syndrome (CFS), an investigation was performed to examine if there is an abnormal excretion of gamma-aminobutyric acid (GABA) and/or its structural analogue beta-alanine in the urine from CFS patients. Both GABA and beta-alanine are inhibitory neurotransmitters in the mammalian central nervous system.

METHODS

The 24 h urine excretion of GABA and beta-alanine was determined by isotope dilution gas chromatography mass spectrometry in 33 CFS patients and 43 healthy controls. The degree of symptoms in both patients and controls was measured by grading of three typical CFS symptoms using a Visual Analogue Scale.

RESULTS

Men had a significantly higher excretion of both beta-alanine and GABA than women. Comparing CFS patients with healthy controls showed no significant difference in excretion of neither beta-alanine nor GABA. No correlation was found between the excretion of beta-alanine or GABA and any of the three characteristic CFS symptoms measured. However, two female and two male CFS patients excreted considerably higher amounts of beta-alanine in their 24 h urine samples than control subjects.

CONCLUSIONS

Increased excretion of beta-alanine was found in a subgroup of CFS patients, indicating that there may be a link between CFS and beta-alanine in some CFS patients.

Why did I get chronic fatigue syndrome? A qualitative interview study of causal attributions in women patients

OBJECTIVES

To explore causal attributions among women with chronic fatigue syndrome (CFS).

DESIGN

Qualitative study where data from individual semi-structured interviews were analysed according to Malterud's systematic text condensation.

SETTING

Bergen, Norway.

SUBJECTS

A purposeful sample of eight women aged 25-55, recruited among members of a self-help organization.

MAIN OUTCOME MEASURES

Accounts of causal attribution for CFS among the informants, focusing on gender.

RESULTS

The participants agreed that their way of living could have increased the vulnerability of their resistance resources. Pressure they put upon themselves, workload burdens without subsequent relaxation, emotional conflicts, or preparing for assumed problem-solving were mentioned as gendered dimensions. They presented different explanations regarding potential triggers encountering their fragile immune systems, most often a virus infection. The participants thought women might have a weaker immune system than men, or that CFS was caused by a virus that women are more likely to catch. In their experience, their symptoms were activated when people put pressure on them, such that they might be nervous as to whether they could live up to the demands of their surroundings, and in the case of emotional strain related to family and work.

CONCLUSION

More studies are needed exploring hypotheses concerning the complex interplay between molecular predispositions and more or less gendered lifestyle issues in CFS. Doctors need to challenge their strong beliefs regarding medically unexplained conditions, where facts still remain unresolved. Recognizing this, the doctor may provide realistic support and advice, and contribute to the establishment of common ground for understanding and managing the condition.

Chronic fatigue syndrome: the need for subtypes

Chronic fatigue syndrome (CFS) is an important condition confronting patients, clinicians, and researchers. This article provides information concerning the need for appropriate diagnosis of CFS subtypes. We first review findings suggesting that CFS is best conceptualized as a separate diagnostic entity rather than as part of a unitary model of functional somatic distress. Next, research involving the case definitions of CFS is reviewed. Findings suggest that whether a broad or more conservative case definition is employed, and whether clinic or community samples are recruited, these decisions will have a major influence in the types of patients selected. Review of further findings suggests that subtyping individuals with CFS on sociodemographic, functional disability, viral, immune, neuroendocrine, neurology, autonomic, and genetic biomarkers can provide clarification for researchers and clinicians who encounter CFS' characteristically confusing heterogeneous symptom profiles. Treatment studies that incorporate subtypes might be particularly helpful in better understanding the pathophysiology of CFS. This review suggests that there is a need for greater diagnostic clarity, and this might be accomplished by subgroups that integrate multiple variables including those in cognitive, emotional, and biological domains.

Cytokine production and modulation: comparison of patients with chronic fatigue syndrome and normal controls

We studied cytokine production in 15 patients with chronic fatigue syndrome (CFS) and 23 controls. CFS patients' peripheral blood mononuclear cells were cultured with lipopolysaccharide or phytohemagglutinin. Enzymatic immunoassay indicated cytokine concentration in culture supernatants. CFS patients showed significantly lower mRNA levels and transforming growth factor-beta1 (TGF-beta1) production. Cytokine dysregulation affects CFS pathogenesis. TGF-beta1 may aid treatment because it affects CFS inflammatory characteristics.

[Chronic infectious mononucleosis]

INTRODUCTION

Chronic infectious mononucleosis is a clinical entity recognized 15 years ago with clearly defined serological criteria: high titres of IgG Epstein-Barr virus (EBV) virus capsid antigen (VCA), IgG EBV early antigen without IgG Epstein-Barr nuclear antigen (EBNA) antibodies.

MATERIAL AND METHODS

This follow-up study lasted for 2 years and included 100 acute infectious mononucleosis patients who were investigated every 6 months. Apart from physical examination we evaluated history, complete blood count and liver function together with 5 commercial ELISA tests: IgM EBV VCA, IgG EBV VCA, IgG EB NA, IgG EBV EA and IgA EBV EA.

RESULTS

Although malaise and fatigue with cervical lymphoadenopathy were the most frequent symptoms, their statistical significance was most established. All laboratory analyses were completely normal during the follow-up period, but there were four patients with acute hepatitis due to hepatitis A virus and adenoviruses. After 6 months of acute illness, two patients without IgG EB NA antibodies who were candidates for chronic disease, presented no other serological findings for chronic disease. It was confirmed that they had delayed serological response due to EBV infection, because one year later they had a completely normal immune status on EBV infection.

CONCLUSION

Chronic infectious mononucleosis seems to be an extraordinary event after acute disease. This conclusion corresponds with literature reports of sporadic cases of this disease.

Outbreaks of human-herpes virus 6 (HHV-6) infection in day-care centers in Belém, Pará, Brazil

A total of 730 children aged less than 7 years, attending 8 day-care centers (DCCs) in Belém, Brazil were followed-up from January to December 1997 to investigate the occurrence of human-herpes virus 6 (HHV-6) infection in these institutional settings. Between October and December 1997 there have been outbreaks of a febrile- and -exanthematous disease, affecting at least 15-20% of children in each of the DCCs. Both serum- and- plasma samples were obtained from 401 (55%) of the 730 participating children for the detection of HHV-6 antibodies by enzyme-linked immunosorbent assay (ELISA), and viral DNA amplification through the nested-PCR. Recent HHV-6 infection was diagnosed in 63.8% (256/401) of them, as defined by the presence of both IgM and IgG-specific antibodies (IgM+/IgG+); of these, 114 (44.5%) were symptomatic and 142 (55.5%) had no symptoms (p = 0.03). A subgroup of 123 (30.7%) children were found to be IgM-/IgG+, whereas the remaining 22 (5.5%) children had neither IgM nor IgG HHV-6- antibodies (IgM-/IgG-). Of the 118 children reacting strongly IgM-positive (> or = 30 PANBIO units), 26 (22.0%) were found to harbour the HHV-6 DNA, as demonstrated by nested-PCR. Taken the ELISA-IgM- and- nested PCR-positive results together, HHV-6 infection was shown to have occurred in 5 of the 8 DCCs under follow-up. Serological evidence of recent infections by Epstein-Barr virus (EBV) and parvovirus B19 were identified in 2.0% (8/401) and 1. 5% (6/401) of the children, respectively. Our data provide strong evidence that HHV-6 is a common cause of outbreaks of febrile/exanthematous diseases among children attending DCCs in the Belém area.

Immunogenetic background of patients with autoimmune fatigue syndrome

We have previously reported that approximately 50% of children with chronic nonspecific complaints were positive for antinuclear antibodies (ANA), and that a novel autoantibody to a 62 kD protein (anti-Sa) was found in 40% of these ANA-positive patients. Therefore, we proposed a distinct disease entity termed autoimmune fatigue syndrome (AIFS). We hypothesized that if autoimmune mechanisms did play an important role in the pathogenesis of AIFS, it is possible that it is immunogenetically regulated as observed in other autoimmune disorders. In order to examine the immunogenetic background of AIFS patients, HLA-A, -B, -C, and -DR loci were analyzed serologically in 61 AIFS patients. AIFS was found to be positively associated with the class I antigen HLA-B61 and with the class II antigen HLA-DR9, with odds ratios of 2.77 (p = 0.015, Pcorr = 0.48) and 2.60 (p= 0.012, Pcorr = 0.17), respectively. A negative association was also found between AIFS and HLA-DR2 with odds ratio of 0.25 (p = 0.029, Pcorr = 0.041). When comparing anti-Sa positive AIFS patients with healthy controls, the odds ratios associated with HLA-B61, DR9, and DR2 were 3.42 (p = 0.021, Pcorr = 0.22), 3.96 (p = 0.0011, Pcorr = 0.015), and 0.16 (p = 0.0022, Porr = 0.031), respectively. Thus, the HLA associations observed in this study suggested that immunogenetic background might play a role in AIFS.

Frequent HHV-6 reactivation in multiple sclerosis (MS) and chronic fatigue syndrome (CFS) patients

BACKGROUND

HHV-6 is a ubiquitous virus and its infection usually occurs in childhood and then becomes a latent infection. HHV-6 reactivation has been shown to play a role in the pathogenesis of AIDS and several other diseases.

OBJECTIVES

To determine what role HHV-6 infection or reactivation plays in the pathogenesis of multiple sclerosis (MS) and chronic fatigue syndrome (CFS).

RESULTS

Twenty-one MS and 35 CFS patients were studied and followed clinically. In these patients, we measured HHV-6 IgG and IgM antibody levels and also analyzed their peripheral blood mononuclear cells (PBMCs) for the presence of HHV-6, using a short term culture assay. In both MS and CFS patients, we found higher levels of HHV-6 IgM antibody and elevated levels of IgG antibody when compared to healthy controls. Seventy percent of the MS patients studied contained IgM antibodies for HHV-6 late antigens (capsid), while only 15% of the healthy donors (HD) and 20% of the patients with other neurological disorders (OND) had HHV-6 IgM antibodies. Higher frequency of IgM antibody was also detected in CFS patients (57.1%) compared to HD (16%). Moreover, 54% of CFS patients exhibited antibody to HHV-6 early protein (p41/38) compared to only 8.0% of the HD. Elevated IgG antibody titers were detected in both the MS and the CFS patients. PBMCs from MS, CFS and HD were analyzed in a short term culture assay in order to detect HHV-6 antigen expressing cells and to characterize the viral isolates obtained as either Variant A or B. Fifty-four percent of MS patients contained HHV-6 early and late antigen producing cells and 87% of HHV-6 isolates were Variant B. Isolates from CFS, patients were predominately Variant A (70%) and isolates from HD were predominately Variant B (67%). Moreover, one isolate from OND was also Variant B. Persistent HHV-6 infection was found in two CFS patients over a period of 2.5 years and HHV-6 specific cellular immune responses were detected in PBMCs from ten CFS patients.

CONCLUSION

In both MS and CFS patients, we found increased levels of HHV-6 antibody and HHV-6 DNA. A decrease in cellular immune responses was also detected in CFS patients. These data suggest that HHV-6 reactivation plays a role in the pathogenesis of these disorders.

Chronic fatigue syndrome beginning suddenly occurs seasonally over the year

The fact that many patients with chronic fatigue syndrome (CFS) have an infectious like sudden onset to their illness has led to the hypothesis that CFS is a medical illness. If CFS were, on the other hand, a psychiatric disorder related to symptom amplification, one would expect illness onset to occur randomly over the calendar year. This study tested that hypothesis with 69 CFS patients whose illness was on the more severe side of the illness spectrum; all patients reported sudden illness onset with the full syndrome of sore throat, fatigue/malaise, and diffuse achiness developing over no longer than a 2-day period. Date of illness onset was distinctly nonrandom. It peaked from November through January and was at its lowest from April through May. These data support the hypothesis that an infectious illness can trigger the onset of CFS.

Immunological response in chronic fatigue syndrome following a graded exercise test to exhaustion

This study was conducted to evaluate the immunological response to an exhaustive treadmill exercise test in 20 female chronic fatigue syndrome patients compared to 14 matched sedentary controls. Venipuncture was performed at baseline and 4 min, 1 hr, and 24 hr postexercise. White blood cells were labeled for monoclonal antibody combinations and were quantified by FACsan. Cytokines were assayed utilizing quantitative RT/PCR. No group difference was seen in VO2peak (28.6 +/- 1.6 vs 30.9 +/- 1.2 ml.kg-1.min-1; P > 0.05). However, 24 hr after exercise the patients' fatigue levels were significantly increased (P < 0.05). The counts of WBC, CD3+ CD8+ cells, CD3+ CD4+ cells, T cells, B cells, natural killer cells, and IFN-gamma changed across time (P's < 0.01). No group differences were seen for any of the immune variables at baseline or after exercise (P's > 0.05). The immune response of chronic fatigue syndrome patients to exhaustive exercise is not significantly different from that of healthy nonphysically active controls.

Changes in immune parameters seen in Gulf War veterans but not in civilians with chronic fatigue syndrome

The purpose of this study was to evaluate immune function through the assessment of lymphocyte subpopulations (total T cells, major histocompatibility complex [MHC] I- and II-restricted T cells, B cells, NK cells, MHC II-restricted T-cell-derived naive and memory cells, and several MHC I-restricted T-cell activation markers) and the measurement of cytokine gene expression (interleukin 2 [IL-2], IL-4, IL-6, IL-10, IL-12, gamma interferon [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]) from peripheral blood lymphocytes. Subjects included two groups of patients meeting published case definitions for chronic fatigue syndrome (CFS)-a group of veterans who developed their illness following their return home from participating in the Gulf War and a group of nonveterans who developed the illness sporadically. Case control comparison groups were comprised of healthy Gulf War veterans and nonveterans, respectively. We found no significant difference for any of the immune variables in the nonveteran population. In contrast, veterans with CFS had significantly more total T cells and MHC II+ T cells and a significantly higher percentage of these lymphocyte subpopulations, as well as a significantly lower percentage of NK cells, than the respective controls. In addition, veterans with CFS had significantly higher levels of IL-2, IL-10, IFN-gamma, and TNF-alpha than the controls. These data do not support the hypothesis of immune dysfunction in the genesis of CFS for sporadic cases of CFS but do suggest that service in the Persian Gulf is associated with an altered immune status in veterans who returned with severe fatiguing illness.

Social support and chronic fatigue syndrome

The role of social support was examined in Chronic Fatigue Syndrome (CFS). Social support has been shown to affect illness outcome in medical disorders, likely due in part to communication between patient and support giver on illness-related concerns. Forty-one participants, 25 of whom had a primary support giver, completed the Beck Depression Inventory, the Perceived Stress Scale, the Profile of Mood States, and the Inventory of Socially Supportive Behaviors (ISSB); the primary support giver completed a modified version of the ISSB indicating the level of support he or she provided and a questionnaire assessing beliefs about CFS. Results indicated that there were no differences among individuals with CFS with or without support on measures of mood and perceived stress. Individuals with CFS and their support givers agreed on the amount of support offered, and extent of support was independent of beliefs concerning etiology. Exploratory analyses revealed that verbal emotional-cognitive support generally was more predictive of mental health than was tangible, less communicative support. The lack of positive effect of social support is discussed in relation to the degree of support offered, and implications for future research are discussed.

Prevalence of human herpesvirus 6 antibody in the population of Belém, Pará, northern Brazil

A total of 497 serum samples obtained from residents of 2 neighbourhoods (Terra-Firme and Guamá) in Belém, Pará, Brazil was tested for the presence of antibody to human herpesvirus 6 (HHV6), using an indirect immunofluorescence assay. The overall seroprevalence was 90%, with seropositivity rates ranging from 75% to 100% in the different age groups and sexes. There was a significant difference between the antibody prevalences in Terra-Firme and Guamá, 94% and 87%, respectively (P = 0.01). The geometric mean titres (GMT) of antibody to HHV6 declined from the first (< or = 2 years) to the sixth (31-40 years) age groups, and slightly increased (GMT > 50) among individuals older than 40 years.

Laboratory studies in breast implant patients: ANA positivity, gammaglobulin levels, and other autoantibodies

Silicone polymers when used in augmentation prosthesis in breast surgery have been associated in the medical literature with various systemic clinical manifestations and abnormal laboratory testing suggestive of an atypical autoimmune disease. The most frequently cited abnormal test result is the antinuclear antibody. The literature regarding this test is reviewed in general, and then specific previous studies analyzed. The present study then compares the rate of positive antinuclear antibody tests in a case series of 3380 breast implant recipients with historical normal controls, and finds a six-fold increase in relative risk of a positive test. Analysis of the data show that this increased tendency is at least partially a function of duration of implant exposure to a significant degree (p < 0.001), and the same data shows it is not patient age related. Possible explanations of this phenomenon are discussed, including animal studies suggesting that silicone serves as an adjuvant, and therefore might have an effect on immune tolerance in the subject population.

Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome

Patients with chronic fatigue syndrome (CFS) often complain of an inability to maintain activity levels and a variety of autonomic-like symptoms that make everyday activity intolerable at times. The purpose of the study was to determine if there were differences in vagal activity at fixed breathing rates in women with CFS. Twelve women with the diagnosis of CFS between the ages of 32 and 59 years volunteered for the study. Healthy women, who were between the ages of 30 and 49, served as controls. Full signal electrocardiograph and respiratory signals were collected during a paced breathing protocol of three fixed breathing rates (8, 12 and 18 breaths/min) performed in the sitting and standing postures. Vagal activity was analyzed by means of heart rate spectral analysis to determine the subject's response to specific breathing rates and postures. Heart rate variability was used as a non-invasive method of measuring the parasympathetic component of the autonomic nervous system. Using this method, although there was significantly less vagal power in the sitting versus the standing postures for both groups, the overall vagal power was significantly lower (p < 0.034) in the CFS group versus healthy controls. Vagal power was also significantly lower (p < 0.01 to p < 0.05) at all breathing rates in both postures except while standing and breathing at 18 breaths/min. Knowledge of the differences in vagal activity for CFS patients may allow stratification for the analysis of other research variables.

Chronic fatigue syndrome: a cognitive approach

Observations concerning the characteristics of patients who presented to a medical clinic with a principal complaint of chronic medically unexplained fatigue (Chronic Fatigue Syndrome or CFS) are described, including the cognitions (thoughts and assumptions) elicited from a sample of these patients who were treated using cognitive behavioural therapy. On the basis of these observations a cognitive theory of the aetiology of CFS is proposed. These observations have implications for the treatment of patients with CFS.

Chronic fatigue syndrome: a clinical and laboratory study with a well matched control group

OBJECTIVE

To investigate the relation between severity of complaints, laboratory data and psychological parameters in patients with chronic fatigue syndrome (CFS).

SUBJECTS

Eighty-eight patients with CFS and 77 healthy controls matched for age, sex and geographical area.

METHODS

Patients and controls visited our outpatient clinic for a detailed medical history, physical examination and psychological tests: Checklist Individual Strength (CIS). Beck Depression Inventory (BDI) and Sickness Impact Profile (SIP). Venous blood was drawn for a complete blood cell count, serum chemistry panel, C-reactive protein and serological tests on a panel of infectious agents.

RESULTS

All patients fulfilled the criteria for CFS as described by Sharpe et al. (J R Soc Med 1991; 84: 118-21), only 18 patients (20.5%) fulfilled the CDC criteria. The outcome of serum chemistry tests and haematological tests were within the normal range. No significant differences were found in the outcome of serological tests. Compared to controls, significant differences were found in the results on the CIS, the BDI, and the SIP. These results varied with the number of complaints (CDC criteria). When the number of complaints was included as the covariate in the analysis, there were no significant differences on fatigue severity, depression, and functional impairment between patients who fulfilled the CDC criteria and patients who did not.

CONCLUSION

It is concluded that the psychological parameters of fatigue severity, depression and functional impairment are related to the clinical severity of the illness. Because the extensive panel of laboratory tests applied in this study did not discriminate between patients and controls, it was not possible to investigate a possible relation between the outcomes of psychological and laboratory testing.

Sleep, sleep deprivation and infectious disease: studies in animals

Common perceptions that the desire for sleep is increased during mild infectious diseases like colds and 'the flu' have fostered beliefs that sleep promotes recovery from infectious disease and that lack of sleep increases susceptibility to infections. However, until recently, the relationship between infectious disease and vigilance received relatively little systematic study. At present, several model systems provide evidence that infectious disease is accompanied by alterations in sleep. Indeed, increased sleepiness, like fever and anorexia, may be viewed as a facet of the acute phase response to infectious challenge. Recent studies also suggest that sleep, sleep deprivation and infectious disease may be related via mechanisms of the immune system (Fig. 1). Data are now accumulating to address questions such as whether immune processes alter sleep, whether sleep or sleep deprivation influences immune competence, and whether sleep facilitates recovery from infectious disease.

Prevalence of human herpesvirus 6 variants A and B in patients with chronic fatigue syndrome

Peripheral blood mononuclear cells collected from 13 patients with chronic fatigue syndrome and 13 healthy controls were analyzed for the presence of human herpesvirus 6 (HHV-6) DNA by variant-specific polymerase chain reaction and dot blot hybridization. HHV-6 DNA was detected in 7 of 13 (53%) patients, and of those 7 patients, 4 were positive for HHV-6 variant A DNA and 3 were for variant B. No HHV-6 DNA was detected in the controls. Serum antibody titers to the late antigen and antibody prevalence to the early antigen of HHV-6 were significantly higher in the patient group. These results suggest active replication of HHV-6 in patients with chronic fatigue syndrome.

Prevalence of human herpesvirus 6 antibody among isolated Amazonian Amerindian communities in Brazil

Human herpesvirus 6 (HHV6) antibody was detected by the anticomplement immunofluorescence test in 65 of 592 serum samples (10.9%) obtained from Amerindians belonging to 4 remote communities inhabiting the Amazon Region of Brazil. Seropositivity rates ranged from 5.4% in the Oyampí to 14.9% in the Tucano. Among the Mekranoiti and Tiriyo, the seroprevalence rates were 12.5% and 11.8%, respectively. In children aged 0-10 years, the prevalences of HHV6 antibody ranged from 5.2% to 24.2%, among the Oyampí and Mekranoiti tribes, respectively. In the 11-20 and > 20 years old age groups, percentages of positivity ranged, in the former group, from 9.5% to 17.5% in the Oyampí and Tucano, respectively and, in the latter group, from 1.3% in the Oyampí to 14.8% in the Tucano. The prevalences of HHV6 antibody decreased regularly through the first 3 age-groups in the Mekranoiti and Tiriyo. In addition, frequencies of seropositivity were consistently higher in males than in females in the Mekranoiti (P < 0.05), Oyampí and Tiriyo tribes.

Human herpesvirus-6 infections in infants admitted to hospital

Virological studies were carried out on 3 to 36-month-old patients admitted to the Children's Hospital of the University of Modena with febrile syndrome from September 1990 to February 1991. Virological tests were carried out for human herpesvirus-6 (HHV-6), Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus 1 (HSV-1), adenoviruses, parainfluenza viruses 1, 2 and 3, respiratory syncytial virus (RSV) and influenza viruses A and B. Viral infections were confirmed in 60.7% patients: 39.6% were correlated with HHV-6, 5.4% with EBV, 5.4% with both HHV-6 and EBV, 5.4% with adenoviruses, 1.8% with HSV-1, 1.8% with CMV and 1.8% with an unidentified herpes-like lymphotropic virus. HHV-6 isolates were obtained from either peripheral blood lymphocytes (PBLs) or pharyngeal secretion of the infected children. HHV-6 infections included both primary infections (72%) and reactivations (28%). Among HHV-6 infected children, 40%, with exanthem subitum, had infections presenting serological evidence of primary infection and virus isolation from PBLs. The remaining cases of primary infection and the cases of reactivation were found in patients with febrile syndrome without rash (60%). HHV-6 isolates were obtained either from PBLs or pharyngeal secretions from these patients. Southern blot hybridization of the DNAs of 4 HHV-6 isolates showed that the circulating HHV-6 strains all appeared similar, but differed from the HHV-6 strain U1102 used as a positive control.