Tag: post-infection syndrome

A neuroinflammatory paradigm can explain Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome and Post-COVID-19 Fatigue Syndrome

Abstract

This thesis illustrates the development of a neuroinflammatory paradigm for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), applicable to Long-COVID related “Post-COVID-19 Fatigue Syndrome” (PCFS).

The brain being devoid of nociceptors, in combination with neuroimaging technology lacking sufficient sensitivity, helps to explain why the chronic but low-level neuroinflammation purported to be present in the brains of ME/CFS (and PCFS) sufferers has gone unreported by patients, and has been largely undetected by scientists, until more recently. Over-activation of microglia and astrocytes is increasingly being proposed to be at the heart of ME/CFS (and PCFS) pathophysiology.

A key Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) study (2014) provided evidence of glial-cell over-activity, implicating neuroinflammation within the brain’s limbic system, of ME/CFS patients. Other cerebral spinal fluid and neuroimaging studies, including a more recent Magnetic Resonance Spectroscopy (MRS)/MRI Thermometry study (2019), have added support to this concept.

Resultant dysfunction of the limbic system and its closely-connected hypothalamus, which in turn leads to a disturbed autonomic nervous system (ANS) and dysfunctional hypothalamic-pituitary-adrenal-axis (HPA-axis) could then account for the diverse range of symptoms reported in ME/CFS (and PCFS). These symptoms include chronic fatigue, flu-like malaise, mood, memory and cognitive problems (limbic system), sleep, taste, visual and thermostatic-control problems (hypothalamus), gastro-intestinal disturbance, cardiovascular problems and hypotension (ANS), as well as increased frequency of urination and lower blood cortisol levels (HPA-axis).

A dysfunctional hypothalamic paraventricular nucleus (PVN), a potentially vulnerable site, within the brains of genetically susceptible people, which functions normally as a stress-control integrator, is proposed to be at the core of ME/CFS (and PCFS) aetiology and pathophysiology.

It is proposed that all triggers of ME/CFS, be they viral (Epstein-Barr Virus is the most common trigger), or non-viral; including other infectious diseases, multiple vaccinations, emotional trauma or chemical toxin shock, share a common triggering mechanism. They are each proposed to manifest themselves as severe physiological stressors, which by a combination of humoral and neural routes, target, the hypothalamic PVN, of genetically susceptible individuals. By exceeding an intrinsic stress-threshold pertaining to the complex neurological circuitry, within the hypothalamic PVN, the triggering stressor is proposed to overload it into a (permanently) iii dysfunctional state.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which causes Coronavirus Disease 2019 (COVID-19), in common with the triggering stressors of ME/CFS, also manifests itself as a severe physiological stressor, due to a cytokine surge at the site of the primary infection (the lungs). This particular stressor is, also, proposed to target the hypothalamic PVN, in genetically susceptible people, thus triggering PCFS. Life’s ongoing physiological stressors, such as physical, mental overexercise, chemical toxin exposure, emotional and financial stress, all of which are known to exacerbate and perpetuate ME/CFS (as well as PCFS) could do so by then targeting a now “compromised” (possibly inflamed) stress-sensitive hypothalamic PVN, by similar routes.

Then if an alternative, but variable (according to fluctuating neuroinflammation of the hypothalamic PVN, itself) stress threshold was exceeded, commonly reported post-exertional malaise (PEM) episodes, more problematic flare-ups, and even more severe prolonged and characteristic relapses could ensue.

It is proposed that a dysfunctional hypothalamic PVN, thereby, acts as an epicentre to a radiating neuroinflammatory response within the brains of ME/CFS (and PCFS) sufferers. A neuroinflammatory pathway, as proposed to be shared by the early-onset stages of several progressive neuroinflammatory (neurodegenerative) diseases could also be shared by ME/CFS, and PCFS. Indeed, this pathway could be shared by other potentially nonprogressive neuroinflammatory disorders, such as the closely-related fibromyalgia, mental health disorders, epilepsy, and migraines.

Might then the “drivers” of the inflammatory process, which sustain glial-cell activation (and neuroinflammation), in ME/CFS (and PCFS), be the perpetuating stressors, themselves, acting in combination with a now “compromised” and stress-sensitive hypothalamic PVN? If so, what then might be the mechanistic detail linking a stressor-targeted hypothalamic PVN and microglial activation in ME/CFS (and PCFS)?

One attractive scenario requiring further investigation involves the release of corticotrophin releasing hormone (CRH), which is released naturally by the hypothalamic PVN due to stress. The chronic release of CRH from a stress-sensitive, dysfunctional hypothalamic PVN might induce microglia activation, leading to chronic neuroinflammation, via the stimulation of mast-cells.

Two papers were published in relation to this neuroinflammatory paradigm for ME/CFS (2018, 2019), followed by another paper (2021), in which a paradigm was presented to explain the more recently emergent, but equally perplexing, Long-COVID related “PostCOVID-19 Fatigue Syndrome” (PCFS).

The neuroinflammatory model presented is both iv coherent and unifying for all triggering stressors and perpetuating stressors of ME/CFS (& PCFS), without the need for subtypes (as many other models require), but it does require validation. To this effect, it is hoped that this neuroinflammatory model will be both thought-provoking, as well as providing a framework for scientific researchers to test, critique, modify, and develop, into the future.

More brain-focussed research, using increasingly sophisticated neuroimaging technology (especially enhanced PET/MRI) is recommended. Then, a brain-signature for both ME/CFS (and PCFS) might even become attainable, within the next decade, perhaps.

Long-COVID related PCFS, affecting millions of people worldwide, presents a golden opportunity for in-depth longitudinal neuroimaging studies (following patients through relapse-recovery cycles) to develop a better understanding of PCFS (and ME/CFS) pathophysiology.

Source: Mackay, A. A neuroinflammatory paradigm can explain Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome and Post-COVID-19 Fatigue Syndrome. PhD Thesis. University of Otago, New Zealand.  https://ourarchive.otago.ac.nz/bitstream/handle/10523/15089/MackayAngus2021PhD.pdf?sequence=1&isAllowed=y (PDF file)

Long COVID: an estrogen-associated autoimmune disease?

Introduction:

Some people who have had severe to a moderate or mild form of COVID-19 disease may suffer from variable and debilitating symptoms for many months after the initial infection. This condition is commonly called “Long COVID”. An exact definition is missing, but symptoms with a duration of more than 2 months are typically considered as Long COVID. The condition is characterized by long-term sequelae and can involve a range of symptoms such as persistent fatigue, headache, shortness of breath, anosmia, muscle weakness, fever, cognitive dysfunction (brain fog), tachycardia, intestinal disorders, and skin manifestations. Long COVID syndrome bears a similarity to the post-infectious syndromes that followed the outbreaks of chikungunya and Ebola.

In general, women appear to be twice as likely to develop Long COVID as men, but only until around age 60, when the risk level becomes similar. In addition to being a woman, older age and a higher body mass index also seem to be risk factors for having Long COVID.

Source: Ortona E, Buonsenso D, Carfi A, Malorni W; Long Covid Kids study group. Long COVID: an estrogen-associated autoimmune disease? Cell Death Discov. 2021 Apr 13;7(1):77. doi: 10.1038/s41420-021-00464-6. PMID: 33850105; PMCID: PMC8042352.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8042352/ (Full text)

Long-haul COVID: heed the lessons from other infection-triggered illnesses

According to the Johns Hopkins Coronavirus Resource Center, more than 115 million people worldwide have been infected with SARS-CoV-2 during the COVID-19 pandemic, with extensive implications for morbidity and mortality. Description of long-term effects of COVID-19 are apparing in the medical literature; the first large cohort study with 6-months’ follow-up has been published, and more data are sure to follow. A small number of studies point not only to persistent imaging and testing abnormalities across several organ systems in the postacute period, but to a high frequency of patient-reported symptoms such as fatigue, insomnia, anxiety and depression, autonomic disturbances, cognitive difficulties, pain, and others. The presence of patient support groups, and the rapid expansion of clinics to manage or treat these symptoms, validate further their existence and impact.
Although the frequency, severity, and potentially the etiology of persistent symptoms can vary, sequelae after COVID-19 appears poised to join the range of other postinfectious syndromes described in the field of infectious diseases.

These often share a common symptom phenotype, which might also meet case definitions for myalgic encephalomyelitis/chronic fatigue syndrome, fibromyalgia, or post-treatment Lyme disease. We hope that researchers and clinicians will draw on these other conditions as they continue to advance scientific understanding of so-called long-haul or persistent COVID-19. We would also argue that there are important lessons to learn and pitfalls to avoid; our specific area of clinical care and research (post-treatment Lyme disease) has remained a fiercely contentious condition for more than 30 years.

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Source: John N Aucott, Alison W Rebman. Long-haul COVID: heed the lessons from other infection-triggered illnesses. The Lancet, CORRESPONDENCE| VOLUME 397, ISSUE 10278, P967-968, MARCH 13, 2021 https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00446-3/fulltext (Full text) 

How “long covid” is shedding light on postviral syndromes

Long covid really shouldn’t have been a surprise, says Vett Lloyd, a biologist at Mount Allison University in Sackville, Canada. “When the pandemic started, the general assumption was that there were two possible outcomes to an infection—you’d either get better or die,” she says.

But there’s a possible third outcome. It’s long been known that a number of disease causing pathogens—some viral and some bacterial—are associated with ongoing post-infection symptoms in a significant minority of patients.

“There was no real reason to think SARS-CoV-2 should be any different than the original SARS, which also caused post-infection syndromes,” says Lloyd. She is one of many researchers who hope that the attention and funding directed towards long covid will help to shed light on how and why other infections can lead to persistent and sometimes debilitating symptoms.

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Source: Owens B. How “long covid” is shedding light on postviral syndromes BMJ 2022; 378 :o2188 doi:10.1136/bmj.o2188  https://www.bmj.com/content/378/bmj.o2188 (Full text)

Predictors of Chronic Fatigue Syndrome and Mood Disturbance After Acute Infection

Abstract:

Prospective cohort studies following individuals from acute infections have documented a prevalent post-infective fatigue state meeting diagnostic criteria for chronic fatigue syndrome (CFS) – that is, a post-infective fatigue syndrome (PIFS). The Dubbo Infection Outcomes Study (DIOS) was a prospective cohort following individuals from acute infection with Epstein-Barr virus (EBV), Ross River virus (RRV), or Q fever through to assessment of caseness for CFS designated by physician and psychiatrist assessments at 6 months. Previous studies in DIOS have revealed that functional genetic polymorphisms in both immunological (pro- and anti-inflammatory cytokines) and neurological (the purinergic receptor, P2X7) genes are associated with both the severity of the acute infection and subsequent prolonged illness.

Principal components analysis was applied to self-report data from DIOS to describe the severity and course of both the overall illness and concurrent mood disturbance. Associations between demographics and acute infection characteristics, with prolonged illness course as well as the PIFS outcome were examined using multivariable statistics. Genetic haplotype-driven functional variations in the neuropeptide Y (NPY) gene previously shown to be associated with brain responses to stress, and to trait anxiety were also examined as predictors.

The sample included 484 subjects (51% female, median age 32, IQR 19-44), of whom 90 (19%) met diagnostic criteria for CFS at 6 months. Participants with greater overall illness severity and concurrent mood disturbance in the acute illness had a more prolonged illness severity (HR = 0.39, 95% CI: 0.34-0.46, p < 0.001) and mood disturbance (HR = 0.36, 95% CI: 0.30-0.42, p < 0.001), respectively. Baseline illness severity and RRV infection were associated with delayed recovery.

Female gender and mood disturbance in the acute illness were associated with prolonged mood disturbance. Logistic regression showed that the odds of an individual being diagnosed with PIFS increased with greater baseline illness severity (OR = 2.24, 95% CI: 1.71-2.94, p < 0.001). There was no association between the NPY haplotypes with overall illness severity or mood disturbance either during the acute illness phase or with prolonged illness (p > 0.05). Severe acute infective illnesses predicted prolonged illness, prolonged mood disturbance and PIFS. These factors may facilitate early intervention to manage both PIFS and mood disturbances.

Source: Sandler CX, Cvejic E, Valencia BM, Li H, Hickie IB, Lloyd AR. Predictors of Chronic Fatigue Syndrome and Mood Disturbance After Acute Infection. Front Neurol. 2022 Jul 25;13:935442. doi: 10.3389/fneur.2022.935442. PMID: 35959390; PMCID: PMC9359311. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9359311/ (Full text)

Webinar: New Hope for Diagnosing and Treating Post-Infection Illnesses: Lessons Learned from HIV/AIDS

Webinar:

Drs. Steven Deeks and David Hardy (Solve M.E. Medical Advisor) — two long-time researchers, clinicians, and veterans of the battle against HIV/AIDS, discussed how current studies on Long Covid, informed by knowledge gained in other fields, could help develop improved ways to diagnose and treat the broader challenge of post-infection illnesses, such as ME/CFS. In their conversation, Drs. Deeks and Hardy discussed the emerging scientific and medical findings, reflected on their HIV/AIDS experience and the importance of patient engagement in research and advocacy, and discussed the prospects for treatments and therapies.

Prevalence of fibromyalgia 10 years after infection with Giardia lamblia: a controlled prospective cohort study

Abstract:

Objectives: To investigate whether acute infection with Giardia lamblia is associated with fibromyalgia 10 years after infection and whether fibromyalgia is associated with irritable bowel syndrome (IBS) and chronic fatigue (CF) in this setting.

Methods: A cohort study was established after an outbreak of G. lamblia in Bergen, Norway, 2004. Laboratory-confirmed cases and a matched control group were followed for 10 years. The main outcome was fibromyalgia 10 years after giardiasis, defined by the 2016 revisions of the fibromyalgia diagnostic criteria using the Fibromyalgia Survey Questionnaire (FSQ).

Results: The prevalence of fibromyalgia was 8.6% (49/572) among Giardia exposed compared to 3.1% (21/673) in controls (p<0.001). Unadjusted odds for having fibromyalgia was higher for Giardia exposed compared to controls (odds ratio (OR): 2.91, 95% confidence interval (CI): 1.72, 4.91), but adjusted for IBS and CF it was not (OR: 1.05, 95% CI: 0.57, 1.95). Among participants without CF the odds for fibromyalgia was 6.27 times higher for participants with IBS than those without (95% CI: 3.31, 11.91) regardless of exposure. Among participants without IBS the odds for fibromyalgia was 4.80 times higher for those with CF than those without (95% CI: 2.75, 8.37).

Conclusions: We found a higher prevalence of fibromyalgia among Giardia exposed compared to controls 10 years after the acute infection. Fibromyalgia was strongly associated with IBS and CF, and the difference between the exposed and controls can be attributed to the high prevalence of IBS and CF among the Giardia exposed. Notably, this study was not designed to establish causality between Giardia exposure and the outcomes.

Source: Hunskar GS, Rortveit G, Litleskare S, Eide GE, Hanevik K, Langeland N, Wensaas KA. Prevalence of fibromyalgia 10 years after infection with Giardia lamblia: a controlled prospective cohort study. Scand J Pain. 2021 Oct 21;22(2):348-355. doi: 10.1515/sjpain-2021-0122. PMID: 34679267. https://www.degruyter.com/document/doi/10.1515/sjpain-2021-0122/html (Full text)

Editorial: Current Insights Into Complex Post-infection Fatigue Syndromes With Unknown Aetiology: The Case of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Beyond

Introduction:

Black plague epidemics in Medieval Europe, the Spanish Flu pandemic during the first world war, and the pandemic of COVID-19 disease are just three devastating examples of the fragile co-existence between human beings and the microbial world. Remarkably, the human immune system with its innate and adaptive arms recognizes and clears the invading pathogens in most cases. However, like a scar after an injury, some people who had suffered from acute infections remain ill long after the clearance of the pathogen itself. These individuals develop complex fatigue-related syndromes whose pathological mechanisms remain poorly understood. A prime example of such syndromes is the Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) characterized by persistent fatigue and post-exertional malaise among other symptoms (1). Unfortunately, its diagnosis remains challenging due to the inexistence of objective biomarkers that could identify cases. However, researchers are gathering around multidisciplinary networks, such as the US ME/CFS Clinician Coalition and the European Network on ME/CFS, with the aim of fostering collaboration, standardizing research and clinical practices, while accelerating biomarker discovery (2–5). Less-known fatigue-related syndromes have been recently reported after the outbreaks of Ebola virus, Dengue virus, and Chikungunya virus in the Tropics (6–8). However, it is still unclear whether these syndromes constitute clinical entities beyond ME/CFS itself.

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Source: Westermeier F, Lacerda EM, Scheibenbogen C and Sepúlveda N (2022) Editorial: Current Insights Into Complex Post-infection Fatigue Syndromes With Unknown Aetiology: The Case of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Beyond. Front. Med. 9:862953. doi: 10.3389/fmed.2022.862953  https://www.frontiersin.org/articles/10.3389/fmed.2022.862953/full (Full text)

Post-corona fatigue-a familiar picture in a new guise?

Abstract:

Background: Myalgic encephalitis or chronic fatigue syndrome (ME/CFS) has again come into focus as a result of coronavirus disease 2019 (COVID-19). Fundamentally problematic is the fact that ME/CFS is considered a separate entity; however, extreme fatigue is also a common symptom of an underlying disease. Our article aims to increase the acceptance of ME/CFS and extreme fatigue facing a symptomatology that is not fully understood, and to highlight the need for research, orientation for physicians, and counselling services for patients.

Materials and methods: Orientative research by focused information gathering.

Results: In various research projects, the hypothesis of post-infectious ME/CFS as an autoimmune disease could be confirmed. In general, the heterogeneity of diagnostic criteria as well as the variety of formulations to describe the symptomatology and different coding options make it difficult to clearly assign symptoms to a clinical picture. Exertion intolerance has been identified as a severe symptom of post-COVID-19 disorder. For this reason, recommendations in international guidelines are currently being revised, especially with regard to pacing. The implications for recommendations in tumor-related fatigue or due to multiple sclerosis are unclear.

Conclusion: Against the background of a decreasing burden of disease due to increasing vaccination rates, research on fatigue should not only include viral diseases.

Source: Buchberger B, Zwierlein R, Rohde V. Post-Corona-Fatigue – das bekannte Bild in neuem Gewand? [Post-corona fatigue-a familiar picture in a new guise?]. Onkologe (Berl). 2022 Feb 17:1-6. German. doi: 10.1007/s00761-022-01102-1. Epub ahead of print. PMID: 35194336; PMCID: PMC8853121. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8853121/ (Article in German) (Full text)

How mycobacterium tuberculosis infection could lead to the increasing risks of chronic fatigue syndrome and the potential immunological effects: a population-based retrospective cohort study

Abstract:

Background: Chronic fatigue syndrome (CFS) has been shown to be associated with infections. Tuberculosis (TB) is a highly prevalent infectious disease. Patients with chronic fatigue syndrome and post-tuberculosis experience similar symptoms. Furthermore, chronic fatigue syndrome and tuberculosis share similar plasma immunosignatures. This study aimed to clarify the risk of chronic fatigue syndrome following the diagnosis of Mycobacterium tuberculosis infection (MTI), by analyzing the National Health Insurance Research Database of Taiwan.

Methods: 7666 patients aged 20 years or older with newly diagnosed Mycobacterium tuberculosis infection during 2000-2011 and 30,663 participants without Mycobacterium tuberculosis infection were identified. Both groups were followed up until the diagnoses of chronic fatigue syndrome were made at the end of 2011.

Results: The relationship between Mycobacterium tuberculosis infection and the subsequent risk of chronic fatigue syndrome was estimated through Cox proportional hazards regression analysis, with the incidence density rates being 3.04 and 3.69 per 1000 person-years among the non-Mycobacterium tuberculosis infection and Mycobacterium tuberculosis infection populations, respectively (adjusted hazard ratio [HR] = 1.23, with 95% confidence interval [CI] 1.03-1.47). In the stratified analysis, the Mycobacterium tuberculosis infection group were consistently associated with a higher risk of chronic fatigue syndrome in the male sex (HR = 1.27, 95% CI 1.02-1.58) and age group of ≥ 65 years old (HR = 2.50, 95% CI 1.86-3.38).

Conclusions: The data from this population-based retrospective cohort study revealed that Mycobacterium tuberculosis infection is associated with an elevated risk of subsequent chronic fatigue syndrome.

Source: Yang TY, Lin CL, Yao WC, Lio CF, Chiang WP, Lin K, Kuo CF, Tsai SY. How mycobacterium tuberculosis infection could lead to the increasing risks of chronic fatigue syndrome and the potential immunological effects: a population-based retrospective cohort study. J Transl Med. 2022 Feb 21;20(1):99. doi: 10.1186/s12967-022-03301-1. PMID: 35189895. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-022-03301-1 (Full text)