Studies on enterovirus in patients with chronic fatigue syndrome

The Enterovirus Theory of Disease Etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Critical Review

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multi-system disease whose etiological basis has not been established. Enteroviruses (EVs) as a cause of ME/CFS have sometimes been proposed, as they are known agents of acute respiratory and gastrointestinal infections that may persist in secondary infection sites, including the central nervous system, muscle, and heart. To date, the body of research that has investigated enterovirus infections in relation to ME/CFS supports an increased prevalence of chronic or persistent enteroviral infections in ME/CFS patient cohorts than in healthy individuals. Nevertheless, inconsistent results have fueled a decline in related studies over the past two decades. This review covers the aspects of ME/CFS pathophysiology that are consistent with a chronic enterovirus infection and critically reviews methodologies and approaches used in past EV-related ME/CFS studies. We describe the prior sample types that were interrogated, the methods used and the limitations to the approaches that were chosen. We conclude that there is considerable evidence that prior outbreaks of ME/CFS were caused by one or more enterovirus groups. Furthermore, we find that the methods used in prior studies were inadequate to rule out the presence of chronic enteroviral infections in individuals with ME/CFS. Given the possibility that such infections could be contributing to morbidity and preventing recovery, further studies of appropriate biological samples with the latest molecular methods are urgently needed.

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.

Human enterovirus in the gastrocnemius of patients with peripheral arterial disease

Background

Peripheral arterial disease (PAD) is characterized by myofiber degeneration and loss of function in muscles of the lower limbs. Human enterovirus (HEV) infection has been implicated in the pathogenesis of a number of muscle diseases. However, its association with PAD has not been studied. In this study, we tested the hypothesis that infectious HEV is present in skeletal muscle of patients with PAD and is associated with severity of disease.

Methods and Results

Gastrocnemius biopsies from 37 patients with PAD and 14 controls were examined for the presence of HEV RNA, viral capsid protein, viral RNA copy number, and viral infectivity. HEV RNA was detected in 54% of the biopsies from patients with PAD but was not detected in muscle biopsies from control patients. This difference in prevalence among PAD and control patients was significant at P<0.001. Viral RNA copy numbers were increased significantly at the later stages of disease; Fontaine Stage IV (10^5.50 copies/mg muscle wet weight, at P<0.005) and Stage III (10^4.87 copies/mg, at P<0.010) compared to Stage II (10^2.50 copies/mg). Viral replication was confirmed by the presence of the negative‐strand of viral RNA in all specimens positive for HEV RNA. Cultures of HeLa and human skeletal muscle cells treated with muscle homogenates showed HEV replication and the presence of HEV capsid protein.

Conclusion

Our data identified infectious HEV in the gastrocnemius of PAD patients but not in controls. Viral copy number and prevalence of infection were higher in the later stages of disease. Our data point to the need for further studies to determine the contribution of HEV infection to the pathophysiology of PAD.

EBV Chronic Infections

The infection from Epstein-Barr virus (EBV) or virus of infectious mononucleosis, together with other herpes viruses' infections, represents a prototype of persistent viral infections characterized by the property of the latency. Although the reactivations of the latent infection are associated with the resumption of the viral replication and eventually with the "shedding", it is still not clear if this virus can determine chronic infectious diseases, more or less evolutive. These diseases could include some pathological conditions actually defined as "idiopathic"and characterized by the "viral persistence" as the more credible pathogenetic factor. Among the so-called idiopathic syndromes, the "chronic fatigue syndrome" (CFS) aroused a great interest around the eighties of the last century when, just for its relationship with EBV, it was called "chronic mononucleosis" or "chronic EBV infection".Today CFS, as defined in 1994 by the CDC of Atlanta (USA), really represents a multifactorial syndrome characterized by a chronic course, where reactivation and remission phases alternate, and by a good prognosis. The etiopathogenetic role of EBV is demonstrated only in a well-examined subgroup of patients, while in most of the remaining cases this role should be played by other infectious agents - able to remain in a latent or persistent way in the host - or even by not infectious agents (toxic, neuroendocrine, methabolic, etc.). However, the pathogenetic substrate of the different etiologic forms seems to be the same, much probably represented by the oxidative damage due to the release of pro-inflammatory cytokines as a response to the triggering event (infectious or not infectious).Anyway, recently the scientists turned their's attention to the genetic predisposition of the subjects affected by the syndrome, so that in the last years the genetic studies, together with those of molecular biology, received a great impulse. Thanks to both these studies it was possibile to confirm the etiologic links between the syndrome and EBV or other herpesviruses or other persistent infectious agents.The mechanisms of EBV latency have been carefully examined both because they represent the virus strategy to elude the response of the immune system of the host, and because they are correlated with those oncologic conditions associated to the viral persistence, particularly lymphomas and lymphoproliferative disorders. Just these malignancies, for which a pathogenetic role of EBV is clearly documented, should represent the main clinical expression of a first group of chronic EBV infections characterized by a natural history where the neoplastic event aroused from the viral persistence in the resting B cells for all the life, from the genetic predisposition of the host and from the oncogenic potentialities of the virus that chronically persists and incurs reactivations.Really, these oncological diseases should be considered more complications than chronic forms of the illness, as well as other malignancies for which a viral - or even infectious - etiology is well recognized. The chronic diseases, in fact, should be linked in a pathogenetic and temporal way to the acute infection, from whom start the natural history of the following disease. So, as for the chronic liver diseases from HBV and HCV, it was conied the acronym of CAEBV (Chronic Active EBV infection), distinguishing within these pathologies the more severe forms (SCAEBV) mostly reported in Far East and among children or adolescents. Probably only these forms have to be considered expressions of a chronic EBV infection "sensu scrictu", together with those forms of CFS where the etiopathogenetic and temporal link with the acute EBV infection is well documented. As for CFS, also for CAEBV the criteria for a case definition were defined, even on the basis of serological and virological findings. However, the lymphoproliferative disorders are excluded from these forms and mantain their nosographic (e.g. T or B cell or NK type lymphomas) and pathogenetic collocation, even when they occur within chronic forms of EBV infection. In the pathogenesis, near to the programs of latency of the virus, the genetic and environmental factors, independent from the real natural history of EBV infection, play a crucial role.Finally, it was realized a review of cases - not much numerous in literature - of chronic EBV infection associated to chronic liver and neurological diseases, where the modern techniques of molecular biology should be useful to obtain a more exact etiologic definition, not always possibile to reach in the past.The wide variety of clinical forms associated to the EBV chronic infection makes difficult the finding of a univocal pathogenetic link. There is no doubt, however, that a careful examination of the different clinical forms described in this review should be useful to open new horizons to the study of the persistent viral infections and the still not well cleared pathologies that they can induce in the human host.

Chronic fatigue syndrome: inflammation, immune function, and neuroendocrine interactions

Investigations into the underlying cause of chronic fatigue syndrome have advanced the field considerably in the past year. Gene microarray data have led to a better understanding of pathogenesis. Recent research has evaluated genetic signatures, described biologic subgroups, and suggested potential targeted treatments. Acute viral infection studies found that initial infection severity was the single best predictor of persistent fatigue. Genomic studies showed that persistent cases express Epstein Barr virus-specific genes and demonstrate abnormalities of mitochondrial function. Studies of immune dysfunction extended observations of natural killer cytotoxic cell dysfunction of the cytotoxic T cell through quantitative evaluation of intracellular perforins and granzymes. Other research has focused on a subgroup of patients with reactivated viral infection. These advances should result in targeted therapies that impact immune function, hypothalamic-pituitary-adrenal axis regulation, and persistent viral reactivation.

Spectroscopic diagnosis of chronic fatigue syndrome by visible and near-infrared spectroscopy in serum samples

To investigate visible and near-infrared (Vis-NIR) spectroscopy enabling chronic fatigue syndrome (CFS) diagnosis, we subjected sera from CFS patients as well as healthy donors to Vis-NIR spectroscopy. Vis-NIR spectra in the 600-1100 nm region for sera from 77 CFS patients and 71 healthy donors were subjected to principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) to develop multivariate models to discriminate between CFS patients and healthy donors. The model was further assessed by the prediction of 99 masked other determinations (54 in the healthy group and 45 in the CFS patient group). The PCA model predicted successful discrimination of the masked samples. The SIMCA model predicted 54 of 54 (100%) healthy donors and 42 of 45 (93.3%) CFS patients of Vis-NIR spectra from masked serum samples correctly. These results suggest that Vis-NIR spectroscopy for sera combined with chemometrics analysis could provide a promising tool to objectively diagnose CFS.

The role of enterovirus in chronic fatigue syndrome

Two and a half decades after coining of the term chronic fatigue syndrome (CFS), the diagnosis of this illness is still symptom based and the aetiology remains elusive. Enteroviruses are well known causes of acute respiratory and gastrointestinal infections, with tropism for the central nervous system, muscles, and heart. Initial reports of chronic enteroviral infections causing debilitating symptoms in patients with CFS were met with skeptism, and had been largely forgotten for the past decade. Observations from in vitro experiments and from animal models clearly established a state of chronic persistence through the formation of double stranded RNA, similar to findings reported in muscle biopsies of patients with CFS. Recent evidence not only confirmed the earlier studies, but also clarified the pathogenic role of viral RNA through antiviral treatment. This review summarises the available experimental and clinical evidence that supports the role of enterovirus in chronic fatigue syndrome.

α1-Antitrypsin and fibromyalgia: new data in favour of the inflammatory hypothesis of fibromyalgia

alpha1-Antitrypsin (AAT) circulates in high serum concentrations, and impregnates most body tissues. AAT has a broad anti-inflammatory spectrum, and modulates most inflammatory reactions occurring in human body. Recently, a possible relationship between AAT deficiency (AAT-D) and fibromyalgia (FM) has been raised, with the finding that intravenous infusions of purified human AAT efficiently controlled FM symptoms in two patients with severe hereditary AAT-D. On the other hand, functional magnetic resonance imaging has detected a significant greater activity in pain sensitive areas of the brain in patients with FM, in response to cutaneous stimuli, providing further evidence for a physiological explanation for FM pain. In recent studies abnormal profiles of inflammation markers in serum and biopsies have been found in FM patients. Since most of these inflammation mediators can be inhibited by AAT, these observations would suggest that at least a subset of the FM syndrome could be related to an inflammatory process, possibly due to an imbalance between inflammatory and anti-inflammatory substances, in the soft body tissues. Future directions of research would be: (1) to develop epidemiological studies to determine the gene frequency of AAT deficiency alleles in FM patients; (2) implementation of a double-blind placebo-controlled clinical trial to determine the specific role of AAT augmentation therapy in AAT-D patients with FM; (3) identification of specific laboratory markers for diagnostic and clinical evaluation purposes in FM; (4) application of the newest medical imaging techniques for diagnosis; and (5) identification of genetic, familial, and environmental risk factors suspected to participate in the FM syndrome development.

Detection of enterovirus in human skeletal muscle from patients with chronic inflammatory muscle disease or fibromyalgia and healthy subjects

Enterovirus RNA has been found previously in specimens of muscle biopsy from patients with idiopathic dilated cardiomyopathy, chronic inflammatory muscle diseases, and fibromyalgia or chronic fatigue syndrome (fibromyalgia/chronic fatigue syndrome). These results suggest that skeletal muscle may host enteroviral persistent infection. To test this hypothesis, we investigated by reverse transcription-polymerase chain reaction (RT-PCR) assay the presence of enterovirus in skeletal muscle of patients with chronic inflammatory muscle diseases or fibromyalgia/chronic fatigue syndrome, and also of healthy subjects. Three of 15 (20%) patients with chronic inflammatory muscle diseases, 4 of 30 (13%) patients with fibromyalgia/chronic fatigue syndrome, and none of 29 healthy subjects was found positive. The presence of VP-1 enteroviral capsid protein was assessed by an immunostaining technique using the 5-D8/1 monoclonal antibody; no biopsy muscle from any patient or healthy subject was found positive. The presence of viral RNA in some muscle biopsies from patients exhibiting muscle disease, together with the absence of VP-1 protein, is in favor of a persistent infection involving defective viral replication.

Chronic fatigue syndrome: probable pathogenesis and possible treatments

Chronic fatigue syndrome (CFS) belongs in the medically unexplained illnesses. It affects approximately 0.2-0.7% of the population in Western countries. It is characterised by unexplained fatigue, lasting 6 months or more, impairment of neurocognitive functions and quality of sleep, and of somatic symptoms, such as recurrent sore throat, muscle aches, arthralgias, headache and postexertional malaise. No link between infections and CFS has been clearly established but the immune system is activated, there are aberrations in several hypothalamic-pituitary axes and involvement of other parts of the central nervous system. No specific treatment has been found. Cognitive behavioural therapy is established to be of value to improve quality of life. More effective treatment should result, as advances in biomedical as well as psychological research continue.

Poliovirus induces an early impairment of mitochondrial function by inhibiting succinate dehydrogenase activity

Poliovirus infection of COS-1 and T47D cells caused a rapid decrease in total cell respiration, and this was attributed to an inhibition of mitochondrial respiration. The stimulation of mitochondrial respiration by pyruvate plus malate or succinate was impaired in saponin-permeabilised cells. However, this inhibition could be overcome by the addition of N,N,N',N'-tetramethyl-1, 4-phenylenediamine and ascorbate. The activity of succinate dehydrogenase was impaired in parallel with the inhibition of mitochondrial respiration during poliovirus infection. This shows that mitochondrial function is profoundly altered during poliovirus infection and that this occurs primarily through inhibition of electron flow at complex II of the mitochondrial respiratory chain.

Elevated, sustained peroxynitrite levels as the cause of chronic fatigue syndrome

The etiology of chronic fatigue syndrome (CFS) has been both obscure and highly contentious, leading to substantial barriers to both clear diagnosis and effective treatment. I propose here a novel hypothesis of CFS in which either viral or bacterial infection induces one or more cytokines, IL-1beta IL-6, TNF-alpha and IFN-gamma. These induce nitric oxide synthase (iNOS), leading to increased nitric oxide levels. Nitric oxide, in turn, reacts with superoxide radical to generate the potent oxidant peroxynitrite. Multiple amplification and positive feedback mechanisms are proposed by which once peroxynitrite levels are elevated, they tend to be sustained at a high level. This proposed mechanism may lower the HPA axis activity and be maintained by consequent lowered glucocorticoid levels. Similarities are discussed among CFS and autoimmune and other diseases previously shown to be associated with elevated peroxynitrite. Multiple pharmacological approaches to the treatment of CFS are suggested by this hypothesis.

Borna disease virus infection in two family clusters of patients with chronic fatigue syndrome

A high rate of Borna disease virus (BDV) infection has been demonstrated in patients with chronic fatigue syndrome (CFS). Herein, we focused on BDV infection in two family clusters of patients with CFS: a father, mother, two sons and one daughter (family #1); and a father, mother, two daughters and one son (family #2). All members, except for the elder son in family #1 and the father and son in family #2, were diagnosed with CFS. The results supported that all the family members with CFS were infected with BDV, as evidenced by the presence of antibodies to viral p40, p24 and/or gp18 and BDV p24 RNA in peripheral blood mononuclear cells. The healthy members, except for the father of family #2 who was positive for antibody to p24, were all negative by both assays. Follow-up studies in family #1 continued to reveal BDV antibodies and BDV RNA, except in the mother, who lost the RNA upon slight recovery from the disease.

Human herpesviruses in chronic fatigue syndrome

We have conducted a double-blind study to assess the possible involvement of the human herpesviruses (HHVs) HHV6, HHV7, Epstein-Barr virus (EBV), and cytomegalovirus in chronic fatigue syndrome (CFS) patients compared to age-, race-, and gender-matched controls. The CFS patient population was composed of rigorously screened civilian and Persian Gulf War veterans meeting the Centers for Disease Control and Prevention's CFS case definition criteria. Healthy control civilian and veteran populations had no evidence of CFS or any other exclusionary medical or psychiatric condition. Patient peripheral blood mononuclear cells were analyzed by PCR for the presence of these HHVs. Using two-tailed Fisher's exact test analyses, we were unable to ascertain any statistically significant differences between the CFS patient and control populations in terms of the detection of one or more of these viruses. This observation was upheld when the CFS populations were further stratified with regard to the presence or absence of major axis I psychopathology and patient self-reported gradual versus acute onset of disease. In tandem, we performed serological analyses of serum anti-EBV and anti-HHV6 antibody titers and found no significant differences between the CFS and control patients.

Sociosomatics and illness in chronic fatigue syndrome

OBJECTIVE

This study examines social processes that construct the course of chronic illness. Specifically, it identifies and describes mechanisms that constitute the process of role constriction in employment for individuals with chronic illness.

METHOD

Sixty-six persons meeting the Centers for Disease Control case definition of chronic fatigue syndrome (CFS) participated in a longitudinal study involving three waves of data collection over 3 years. Qualitative and quantitative methods were combined in the research, which included face-to-face semistructured interviews, telephone interviews, and self-report questionnaires. Materials presented in this study are drawn principally from the Year 1 face-to-face and telephone interviews.

RESULTS

When patterns of symptoms and of the illness course in CFS intersect with work requirements, they impede performance and place ill individuals at risk for job loss. Persons with CFS devise and implement specific strategies to resist role constriction and remain in the work force.

CONCLUSIONS

Role constriction is a social process of marginalization in chronic illness. Opposing forces of marginalization and resistance define the social course in chronic illness and suggest that chronicity can be thought of as a marginalized position in social space.

Chronic fatigue syndrome. A practical guide to assessment and management

Chronic fatigue and chronic fatigue syndrome (CFS) have become increasingly recognized as a common clinical problem, yet one that physicians often find difficult to manage. In this review we suggest a practical, pragmatic, evidence-based approach to the assessment and initial management of the patient whose presentation suggests this diagnosis. The basic principles are simple and for each aspect of management we point out both potential pitfalls and strategies to overcome them. The first, and most important task is to develop mutual trust and collaboration. The second is to complete an adequate assessment, the aim of which is either to make a diagnosis of CFS or to identify an alternative cause for the patient's symptoms. The history is most important and should include a detailed account of the symptoms, the associated disability, the choice of coping strategies, and importantly, the patient's own understanding of his/her illness. The assessment of possible comorbid psychiatric disorders such as depression or anxiety is mandatory. When the physician is satisfied that no alternative physical or psychiatric disorder can be found to explain symptoms, we suggest that a firm and positive diagnosis of CFS be made. The treatment of CFS requires that the patient is given a positive explanation of the cause of his symptoms, emphasizing the distinction among factors that may have predisposed them to develop the illness (lifestyle, work stress, personality), triggered the illness (viral infection, life events) and perpetuated the illness (cerebral dysfunction, sleep disorder, depression, inconsistent activity, and misunderstanding of the illness and fear of making it worse). Interventions are then aimed to overcoming these illness-perpetuating factors. The role of antidepressants remains uncertain but may be tried on a pragmatic basis. Other medications should be avoided. The only treatment strategies of proven efficacy are cognitive behavioral ones. The most important starting point is to promote a consistent pattern of activity, rest, and sleep, followed by a gradual return to normal activity; ongoing review of any 'catastrophic' misinterpretation of symptoms and the problem solving of current life difficulties. We regard chronic fatigue syndrome as important not only because it represents potentially treatable disability and suffering but also because it provides an example for the positive management of medically unexplained illness in general.

Consequences of live poliovirus vaccine administration in chronic fatigue syndrome

The effect of live oral polio virus vaccination on chronic fatigue syndrome (CFS) patients was examined in a double-blind study. CFS patients were allocated randomly to placebo (N = 7) or vaccine (N = 7) conditions. All controls subjects received the vaccine (9). Vaccine administration was not associated with clinical exacerbation of CFS. However, objective responses to the vaccine revealed differences between patients and controls: increased poliovirus isolation, earlier peak proliferative responses, lower T-cell subsets on certain days post vaccination and a trend for reduced gamma-interferon in the CFS-vaccine group. Polio vaccination was not found to be clinically contraindicated in CFS patients, however, there was evidence of altered immune reactivity and virus clearance.

Search for picornaviruses at onset of inflammatory myopathy

Picornaviruses may not play a role as persistent agents in the inflammatory myopathies, but it is still thought likely that they may act as triggers of an autoimmune process. Forty one muscle biopsy specimens, taken from three weeks to six months (mean four months) after onset, were examined using three different picornaviral primers and PCR. Moderate to severe disease activity was evident in all specimens. The results were compared with those of 18 biopsy specimens examined later in the disease course, and with specimens from 27 patients with non-inflammatory myopathies. All results were negative. Thus, even as early as three weeks after clinical disease appears, picornaviruses are not detectable in these disorders.

Chronic fatigue and minor psychiatric morbidity after viral meningitis: a controlled study

OBJECTIVE

To test the hypotheses that patients exposed to viral meningitis would be at an increased risk of developing chronic fatigue syndrome and would have an excess of neurological symptoms and physical impairment.

METHODS

Eighty three patients were followed up 6-24 months after viral meningitis and a postal questionnaire was used to compare outcome with 76 controls who had had non-enteroviral, non-CNS viral infections.

RESULTS

For the 159 patients and controls the prevalence of chronic fatigue syndrome was 12.6%, a rate higher than previously reported from primary care attenders, suggesting that moderate to severe viral infections may play a part in the aetiology of some fatigue states. Those with a history of meningitis showed a slight, non-significant increase in prevalence of chronic fatigue syndrome (OR 1.4; 95% CI 0.5-3.6) which disappeared when logistic regression and analysis was used to correct for age, sex, and duration of follow up (OR 1.0; 95% CI 0.3-2.8). Controls showed marginally higher psychiatric morbidity measured on the general health questionnaire-12 (adjusted OR 0.6; 95% CI 0.3-1.3) Both groups had similar rates of neurological symptoms and physical impairment. The best predictor of chronic fatigue was a prolonged duration time of off work after the illness (OR 4.93, 95% CI 1.3-18.8). The best predictor of severe chronic fatigue syndrome diagnosed by Center for Disease Control criteria was past psychiatric illness (OR 7.82, 95% CI 1.8-34.3). Duration of viral illness, as defined by days in hospital, did not predict chronic fatigue syndrome.

CONCLUSIONS

(1) The prevalence of chronic fatigue syndrome is higher than expected for the range of viral illnesses examined; (2) enteroviral infection is unlikely to be a specific risk factor for its development; (3) onset of chronic fatigue syndrome after a viral infection is predicted by psychiatric morbidity and prolonged convalescence, rather than by the severity of the viral illness itself.

A case-control study to assess possible triggers and cofactors in chronic fatigue syndrome

PURPOSE

To assess possible triggers and cofactors for chronic fatigue syndrome (CFS) and to compare levels of selected cytokines between cases and an appropriately matched control group.

PATIENTS AND METHODS

We conducted a case-control study of 47 cases of CFS obtained through a regional CFS research program maintained at a tertiary care medical center. One age-, gender-, and neighborhood-matched control was identified for each case through systematic community telephone sampling. Standardized questionnaires were administered to cases and controls. Sera were assayed for transforming growth factor-beta (TGF-beta), interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and antibody to Borrelia burgdorferi and Babesia microti.

RESULTS

Cases were more likely to have exercised regularly before illness onset than controls (67% versus 40%; matched odds ratio (MOR) = 3.4; 95% CI = 1.2 to 11.8; P = 0.02). Female cases were more likely to be nulliparous prior to onset of CFS than controls (51% versus 31%; MOR = 8.0; 95% CI = 1.03 to 170; P = 0.05). History of other major factors, including silicone-gel breast implants (one female case and one female control), pre-morbid history of depression (15% of cases, 11% of controls) and history of allergies (66% of cases, 51% of controls) were similar for cases and controls. However, cases were more likely to have a diagnosis of depression subsequent to their diagnosis of CFS compared to a similar time frame for controls (MOR = undefined; 95% CI lower bound = 2.5; P < 0.001). Positive antibody titers to B burgdorferi (one case and one control) and B microti (zero cases and two controls) were also similar.

CONCLUSIONS

Further investigation into the role of prior routine exercise as a cofactor for CFS is warranted. This study supports the concurrence of CFS and depression, although pre-morbid history of depression was similar for both groups.

alpha-Interferon treatment of patients with chronic fatigue syndrome

Thirty patients who fulfilled clinical criteria defined by the CDC for Chronic Fatigue Syndrome were treated with alfa 2a interferon or placebo in a double-blind crossover study. Outcome was evaluated by Natural Killer (NK) cell function, lymphocyte proliferation to mitogens and soluble antigens, CD4/CD8 counts and a 10 item Quality of Life (QOL) survey. Although mean NK function rose from 87.8 +/- 19.6 to 129.3 +/- 20.7 lytic untis (LU; p < .05) with 12 weeks of interferon therapy, there was no significant change in the other immunologic parameters or QOL scores. When the 26 patients who completed the study were stratified according to their baseline NK function and lymphocyte proliferation, 4 groups were identified: 3 patients had normal NK cell function and lymphocyte proliferation when compared to normal, healthy controls, 9 had isolated deficiency in lymphocyte proliferation, 7 had diminished NK function only, and 7 had abnormalities for both parameters. QOL scores were not significantly different for the four groups at baseline. After 12 weeks of interferon therapy, QOL score significantly improved in each of the seven patients with isolated NK cell dysfunction (mean score, 16.3 +/- 7.9) compared to baseline (39.7 +/- 12.1; p < .05). In these patients the mean NK function increased from 35.1 +/- 11.7 to 91.5 +/- 22.7 LU (p < .01). Significant improvement was not recorded for QOL in the other three groups. Thus, therapy with alpha interferon has a significant effect on the QOL of that subgroup of patients with CFS manifesting an isolated decrease in NK function.

No findings of enteroviruses in Swedish patients with chronic fatigue syndrome

Enteroviruses have been proposed to cause an immune complex disease in the chronic fatigue syndrome. Altogether 34 patients with the chronic fatigue syndrome, according to criteria of the Centers for Disease Control, USA, were studied evenly over the seasons for the possible presence of a chronic enterovirus infection. In 11 patients, 1-5 faecal samples were collected at about 6 month intervals for virus isolation before and after acid treatment, followed by ultracetrifugation at pH 3 to dissolve possible enterovirus-antibody complexes. Another 14 fecal samples were subjected to routine virus isolation alone. Seven pairs of serum-cerebrospinal fluid samples were analysed for cross-reactive IgG antibody activity to enteroviruses. In 29 patients a muscle biopsy was collected for enterovirus polymerase chain reaction (PCR). We were unable to identify enteroviruses in any of these samples by any of these techniques. Our study does not confirm evidence for persistent enterovirus infection in the chronic fatigue syndrome.

Search for persistent infection with poliovirus or other enteroviruses in amyotrophic lateral sclerosis-motor neurone disease

A longstanding hypothesis proposes that amyotrophic lateral sclerosis-motor neurone disease (ALS-MND) is a late consequence of subclinical poliovirus (PV) infection. In this study, RNA extracts of CNS tissue from 28 patients with ALS-MND and 7 controls were assayed by nested polymerase chain reaction (PCR) using primers to the 5'-untranslated region (UTR) of the enterovirus (EV) genome which is highly conserved between EVs including PV, echovirus and coxsackie viruses. The integrity of RNA extracted from either archival paraffin-embedded or frozen CNS tissue was assessed by detection of constitutive Ableson tyrosine kinase (ABL) mRNA by PCR. Of 63 tissue samples assayed, 81% (51/63) were ABL-positive corresponding to 78% (22/28) of the ALS-MND cases and all controls. None of the 27 ALS-MND cases (i.e. 21 ABL+ and 6 ABL-) in which paraffin-embedded tissue was used nor any of the age and sex matched controls were positive for specific PV/EV RNA. Moreover, CNS tissue from 14 different locations obtained from one patient < 2 hrs after death and immediately frozen, showed no evidence of PV/EV at any site by PCR. Disease duration, degree of tissue autolysis and duration of tissue storage were all excluded as factors which may predispose to negative results. The sensitivity of the PV PCR was determined to be 40-400 copies (12.5 - 125 ag) of synthetic EV RNA transcripts in 1 microgram of cellular RNA and the assay was shown to detect all types of PV and and other EVs tested. Thus it seems unlikely that a persistent PV or related EV infection is implicated in ALS-MND unless there has been alteration in the 5'-UTR of the virus genome.

Coping with chronic fatigue syndrome: illness responses and their relationship with fatigue, functional impairment and emotional status

The implications of patients' approaches to managing chronic fatigue syndrome were examined in a cross-sectional study. With severity of fatigue controlled, attempting to maintain activity was associated with less functional impairment, while accommodating to the illness was positively related to impairment; behavioural disengagement was related not only to higher levels of impairment but also to greater emotional disturbance. Fatigue itself was positively associated with focusing on symptoms and with behavioural disengagement; it was associated also with illness accommodation, but only for illness of longer duration. The causal direction of relationships between coping and fatigue severity is ambiguous, and a follow-up study will address the effects of coping on changes in the illness over time.

Viruses, neurosis and fatigue

The evidence for viral infections as a cause of anxiety, depression and fatigue is reviewed. It is argued that in order to fully understand any proposed relationship the effects of psychosocial factors on immunity, convalescence and illness behaviour must be acknowledged.