Neurological events related to influenza A (H1N1) pdm09

COVID-19 and the impact on Alzheimer's disease pathology

Coronavirus disease 2019 (COVID-19) has rapidly escalated into a global pandemic that primarily affects older and immunocompromised individuals due to underlying clinical conditions and suppressed immune responses. Furthermore, COVID-19 patients exhibit a spectrum of neurological symptoms, indicating that COVID-19 can affect the brain in a variety of manners. Many studies, past and recent, suggest a connection between viral infections and an increased risk of neurodegeneration, raising concerns about the neurological effects of COVID-19 and the possibility that it may contribute to Alzheimer's disease (AD) onset or worsen already existing AD pathology through inflammatory processes given that both COVID-19 and AD share pathological features and risk factors. This leads us to question whether COVID-19 is a risk factor for AD and how these two conditions might influence each other. Considering the extensive reach of the COVID-19 pandemic and the devastating impact of the ongoing AD pandemic, their combined effects could have significant public health consequences worldwide.

Evaluation of disease severity and prediction of severe cases in children hospitalized with influenza A (H1N1) infection during the post-COVID-19 era: a multicenter retrospective study

BACKGROUND

The rebound of influenza A (H1N1) infection in post-COVID-19 era recently attracted enormous attention due the rapidly increased number of pediatric hospitalizations and the changed characteristics compared to classical H1N1 infection in pre-COVID-19 era. This study aimed to evaluate the clinical characteristics and severity of children hospitalized with H1N1 infection during post-COVID-19 period, and to construct a novel prediction model for severe H1N1 infection.

METHODS

A total of 757 pediatric H1N1 inpatients from nine tertiary public hospitals in Yunnan and Shanghai, China, were retrospectively included, of which 431 patients diagnosed between February 2023 and July 2023 were divided into post-COVID-19 group, while the remaining 326 patients diagnosed between November 2018 and April 2019 were divided into pre-COVID-19 group. A 1:1 propensity-score matching (PSM) was adopted to balance demographic differences between pre- and post-COVID-19 groups, and then compared the severity across these two groups based on clinical and laboratory indicators. Additionally, a subgroup analysis in the original post-COVID-19 group (without PSM) was performed to investigate the independent risk factors for severe H1N1 infection in post-COIVD-19 era. Specifically, Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to select candidate predictors, and logistic regression was used to further identify independent risk factors, thus establishing a prediction model. Receiver operating characteristic (ROC) curve and calibration curve were utilized to assess discriminative capability and accuracy of the model, while decision curve analysis (DCA) was used to determine the clinical usefulness of the model.

RESULTS

After PSM, the post-COVID-19 group showed longer fever duration, higher fever peak, more frequent cough and seizures, as well as higher levels of C-reactive protein (CRP), interleukin 6 (IL-6), IL-10, creatine kinase-MB (CK-MB) and fibrinogen, higher mechanical ventilation rate, longer length of hospital stay (LOS), as well as higher proportion of severe H1N1 infection (all P < 0.05), compared to the pre-COVID-19 group. Moreover, age, BMI, fever duration, leucocyte count, lymphocyte proportion, proportion of CD3+ T cells, tumor necrosis factor α (TNF-α), and IL-10 were confirmed to be independently associated with severe H1N1 infection in post-COVID-19 era. A prediction model integrating these above eight variables was established, and this model had good discrimination, accuracy, and clinical practicability.

CONCLUSIONS

Pediatric H1N1 infection during post-COVID-19 era showed a higher overall disease severity than the classical H1N1 infection in pre-COVID-19 period. Meanwhile, cough and seizures were more prominent in children with H1N1 infection during post-COVID-19 era. Clinicians should be aware of these changes in such patients in clinical work. Furthermore, a simple and practical prediction model was constructed and internally validated here, which showed a good performance for predicting severe H1N1 infection in post-COVID-19 era.

Changes in the Expression of Proteins Associated with Neurodegeneration in the Brains of Mice after Infection with Influenza A Virus with Wild Type and Truncated NS1

Influenza type A virus (IAV) infection is a major cause of morbidity and mortality during influenza epidemics. Recently, a specific link between IAV infection and neurodegenerative disease progression has been established. The non-structural NS1 protein of IAV regulates viral replication during infection and antagonizes host antiviral responses, contributing to influenza virulence. In the present study, we have prepared a mouse lung-to-lung adapted to the NS1-truncated virus (NS80ad). Transcriptome analysis of the gene expression in the lungs revealed that infection with wild-type A/WSN/33 (WSN), NS80, and NS80ad viruses resulted in different regulation of genes involved in signaling pathways associated with the cell proliferation, inflammatory response, and development of neurodegenerative diseases. NS1 protein did not influence the genes involved in the RIG-I-like receptor signaling pathway in the brains. Lethal infection with IAVs dysregulated expression of proteins associated with the development of neurodegenerative diseases (CX3CL1/Fractalkine, Coagulation factor III, and CD105/Endoglin, CD54/ICAM-1, insulin-like growth factor-binding protein (IGFBP)-2, IGFBP-5, IGFBP-6, chitinase 3-like 1 (CHI3L1), Myeloperoxidase (MPO), Osteopontin (OPN), cystatin C, and LDL R). Transcription of GATA3 mRNA was decreased, and expression of MPO was inhibited in the brain infected with NS80 and NS80ad viruses. In addition, the truncation of NS1 protein led to reduced expression of IGFBP-2, CHI3L1, MPO, and LDL-R proteins in the brains. Our results indicate that the influenza virus influences the expression of proteins involved in brain function, and this might occur mostly through the NS1 protein. These findings suggest that the abovementioned proteins represent a promising target for the development of potentially effective immunotherapy against neurodegeneration.

SARS-CoV-2, aging, and Post-COVID-19 neurodegeneration

As the world continues to experience the effects of SARS-CoV-2, there is evidence to suggest that the sequelae of viral infection (the post-COVID-19 condition; PCC) at both an individual and population level will be significant and long-lasting. The history of pandemics or epidemics in the last 100 years caused by members of the RNA virus family, of which coronaviruses are a member, provides ample evidence of the acute neurological effects. However, except for the H1N1 influenza pandemic of 1918/1919 (the Spanish flu) with its associated encephalitis lethargica, there is little information on long-term neurological sequelae. COVID-19 is the first pandemic that has occurred in a setting of an aging population, especially in several high-income countries. Its survivors are at the greatest risk for developing neurodegenerative conditions as they age, rendering the current pandemic a unique paradigm not previously witnessed. The SARS-CoV-2 virus, among the largest of the RNA viruses, is a single-stranded RNA that encodes for 29 proteins that include the spike protein that contains the key domains required for ACE2 binding, and a complex array of nonstructural proteins (NSPs) and accessory proteins that ensure the escape of the virus from the innate immune response, allowing for its efficient replication, translation, and exocytosis as a fully functional virion. Increasingly, these proteins are also recognized as potentially contributing to biochemical and molecular processes underlying neurodegeneration. In addition to directly being taken up by brain endothelium, the virus or key protein constituents can be transported to neurons, astrocytes, and microglia by extracellular vesicles and can accelerate pathological fibril formation. The SARS-CoV-2 nucleocapsid protein is intrinsically disordered and can participate in liquid condensate formation, including as pathological heteropolymers with neurodegenerative disease-associated RNA-binding proteins such as TDP-43, FUS, and hnRNP1A. As the SARS-CoV-2 virus continues to mutate under the immune pressure exerted by highly efficacious vaccines, it is evolving into a virus with greater transmissibility but less severity compared with the original strain. The potential of its lingering impact on the nervous system thus has the potential to represent an ongoing legacy of an even greater global health challenge than acute infection.

Neurological features related to influenza virus in the pediatric population: a 3-year monocentric retrospective study

Influenza virus is generally characterized by fever, myalgia, and respiratory symptoms. Neurological entities have already been described, such as acute necrotizing encephalitis (ANE). We aimed to highlight the non-exceptional nature and explore the clinical spectrum and evolution of neurological features related to influenza virus in children. This monocentric observational study included patients under 18 years old, positive for influenza virus, between January 2017 and April 2019 in a pediatric university hospital. Patients were classified into two groups: those with or without a previous significant neurological or metabolic disorder. Two hundred eighty-nine children were identified with influenza infection. Thirty seven had a neurological manifestation: 14 patients who had previous significant neurological or metabolic disorder and 23 patients with no medical history. We identified several clinical patterns: 22 patients had seizures, 7 behavior disorders, 5 disturbances of consciousness, and 3 motor deficits. Four were diagnosed with a known influenza-associated neurological syndrome: 1 ANE, 1 cytotoxic lesion of the corpus callosum, 1 hemiconvulsion-hemiplegia-epilepsia syndrome, and 1 recurrent encephalitis in the context of a RANBP2 mutation. The neurological outcome was favorable in most cases. None of the patients with previous significant disorder retained sequalae or had a recurrence. Two patients had a fatal outcome, and both had a predisposing disorder.

CONCLUSION

Various neurological manifestations can be associated with influenza virus. Certain entities led to a poor prognosis, but in most cases, symptoms improved within a few days. The severity of the neurological manifestations correlated with previous neurological or metabolic disorders.

WHAT IS KNOWN

• Influenza viruses are well known pathogens with a seasonal epidemic evolution, particularly affecting children. These viruses cause acute fever with respiratory symptoms, associated with myalgia and headaches. Neurological presentation in influenza-virus infection is a well-established possibility as influenza virus is considered to be responsible for 27 to 36% of childhood encephalitis. Some specific and severe entity as acute necrotizing encephalitis, cytotoxic lesion of the corpus callosum, or Hemiconvulsion-hemiplegia-epilepsy syndrome are well described.

WHAT IS NEW

• In a French monocentric cohort of 37 children with influenza-related neurologic manifestations, the majority of these manifestations, including seizure, drowsiness, motor deficiency, hallucination… are self limiting and do not lead to after-effects. In rare cases (4/37), they may reveal severe encephalitis requiring rapid and appropriate treatment. Otherwise, comparison of a group of 14 children with underlying neurological or metabolic disorder with a group of 23 children free of any significant disorder show that the severity of the neurological manifestations was largely related to previous neurological or metabolic disorders highlighting the importance of vaccination in this population.

Exploring the Correlation Between Influenza A Virus (H3N2) Infections and Neurological Manifestations: A Scoping Review

Influenza A virus (IAV), particularly the H3N2 variant, is known to cause respiratory manifestations, but it can also lead to neurological complications ranging from mild symptoms like headache and dizziness to severe conditions such as encephalitis and acute necrotizing encephalopathy (ANE). In this article, the correlation between the H3N2 variant of the IAV and neurological manifestations is discussed. Additionally, prompt recognition and treatment of influenza-associated neurological manifestations are highlighted to prevent infection-related long-term complications. This review briefly discusses various neurological complications linked to IAV infections, such as encephalitis, febrile convulsions, and acute disseminated encephalomyelitis, and the potential mechanisms involved in the development of neurological complications.

The Effects of Viruses on Insulin Sensitivity and Blood-Brain Barrier Function

In this review manuscript, we discuss the effects of select common viruses on insulin sensitivity and blood-brain barrier (BBB) function and the potential overlapping and distinct mechanisms involved in these effects. More specifically, we discuss the effects of human immunodeficiency virus (HIV), herpes, hepatitis, influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 viruses on insulin sensitivity and BBB function and the proposed underlying mechanisms. These viruses differ in their ability to be transported across the BBB, disrupt the BBB, and/or alter the function of the BBB. For RSV and SARS-CoV-2, diabetes increases the risk of infection with the virus, in addition to viral infection increasing the risk for development of diabetes. For HIV and hepatitis C and E, enhanced TNF-a levels play a role in the detrimental effects. The winter of 2022-2023 has been labeled as a tridemic as influenza, RSV, and COVID-19 are all of concern during this flu season. There is an ongoing discussion about whether combined viral exposures of influenza, RSV, and COVID-19 have additive, synergistic, or interference effects. Therefore, increased efforts are warranted to determine how combined viral exposures affect insulin sensitivity and BBB function.

Neurological sequelae of vaccines

IMPORTANCE

Vaccines are a safe and efficacious way to prevent a variety of infectious diseases. Over the course of their existence, vaccines have prevented immeasurable morbidity and mortality in humans. Typical symptoms of systemic immune activation are common after vaccines and may include local soreness, myalgias, nausea, and malaise. In the vast majority of cases, the severity of the infectious disease outweighs the risk of mild adverse reactions to vaccines. Rarely, vaccines may be associated with neurological sequela that ranges in severity from headache to transverse myelitis, acute disseminated encephalomyelitis, and Guillain-Barre syndrome (GBS). Often, a causal link cannot be confirmed, and it remains unclear if disease onset is directly related to a recent vaccination.

OBSERVATIONS

This review serves to summarize reported neurologic sequelae of commonly used vaccines. It will also serve to discuss potential pathogenesis. It is important to note that many adverse events or reactions to vaccines are self-reported into databases, and causal proof cannot be obtained.

CONCLUSIONS AND RELEVANCE

Recognition of reported adverse effects of vaccines plays an important role in public health and education. Early identification of these symptoms can allow for rapid diagnosis and potential treatment. Vaccines are a safe option for prevention of infectious diseases.

Identifying cerebral microstructural changes in patients with COVID-19 using MRI: A systematic review

Coronavirus disease 2019 (COVID-19) is an epidemic viral disease caused by a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite the excessive number of neurological articles that have investigated the effect of COVID-19 on the brain from the neurological point of view, very few studies have investigated the impact of COVID-19 on the cerebral microstructure and function of the brain. The aim of this study was to summarize the results of the existing studies on cerebral microstructural changes in COVID-19 patients, specifically the use of quantitative volumetric analysis, blood oxygen level dependent (BOLD), and diffusion tensor imaging (DTI). We searched PubMed/MEDLINE, ScienceDirect, Semantic Scholar, and Google Scholar from December 2020 to April 2022. A well-constructed search strategy was used to identify the articles for review. Seven research articles have met this study's inclusion and exclusion criteria, which have applied neuroimaging tools such as quantitative volumetric analysis, BOLD, and DTI to investigate cerebral microstructure changes in COVID-19 patients. A significant effect of COVID-19 was found in the brain such as hypoperfusion of cerebral blood flow, increased gray matter (GM) volume, and reduced cortical thickness. The insula and thalamic radiation were the most frequent GM region and white matter tract, respectively, that are involved in SARS-CoV-2. COVID-19 was found to be associated with changes in cerebral microstructures. These abnormalities in brain areas might lead to be associated with behaviors, mental and neurological alterations that need to be considered carefully in future studies.

Investigating neurological symptoms of infectious diseases like COVID-19 leading to a deeper understanding of neurodegenerative disorders such as Parkinson's disease

Apart from common respiratory symptoms, neurological symptoms are prevalent among patients with COVID-19. Research has shown that infection with SARS-CoV-2 accelerated alpha-synuclein aggregation, induced Lewy-body-like pathology, caused dopaminergic neuron senescence, and worsened symptoms in patients with Parkinson's disease (PD). In addition, SARS-CoV-2 infection can induce neuroinflammation and facilitate subsequent neurodegeneration in long COVID, and increase individual vulnerability to PD or parkinsonism. These findings suggest that a post-COVID-19 parkinsonism might follow the COVID-19 pandemic. In order to prevent a possible post-COVID-19 parkinsonism, this paper reviewed neurological symptoms and related findings of COVID-19 and related infectious diseases (influenza and prion disease) and neurodegenerative disorders (Alzheimer's disease, PD and amyotrophic lateral sclerosis), and discussed potential mechanisms underlying the neurological symptoms and the relationship between the infectious diseases and the neurodegenerative disorders, as well as the therapeutic and preventive implications in the neurodegenerative disorders. Infections with a relay of microbes (SARS-CoV-2, influenza A viruses, gut bacteria, etc.) and prion-like alpha-synuclein proteins over time may synergize to induce PD. Therefore, a systematic approach that targets these pathogens and the pathogen-induced neuroinflammation and neurodegeneration may provide cures for neurodegenerative disorders. Further, antiviral/antimicrobial drugs, vaccines, immunotherapies and new therapies (e.g., stem cell therapy) need to work together to treat, manage or prevent these disorders. As medical science and technology advances, it is anticipated that better vaccines for SARS-CoV-2 variants, new antiviral/antimicrobial drugs, effective immunotherapies (alpha-synuclein antibodies, vaccines for PD or parkinsonism, etc.), as well as new therapies will be developed and made available in the near future, which will help prevent a possible post-COVID-19 parkinsonism in the 21st century.

Somatosensory abnormalities after infection with SARS-CoV-2 - A prospective case-control study in children and adolescents

Background

Long-term neurological complaints after SARS-CoV-2 infection occur in 4-66% of children and adolescents. Controlled studies on the integrity of the peripheral nerve system are scarce. Therefore, we examined the somatosensory function in children and adolescents after SARS-CoV-2 infection in a case-control study compared with age-matched individuals.

Materials and Methods

Eighty-one subjects after SARS-CoV-2 infection (n = 44 female, 11.4 ± 3.5 years, n = 75 SARS-CoV-2 seropositive, n = 6 PCR positive during infection and SARS-CoV-2 seronegative at the time point of study inclusion, n = 47 asymptomatic infection) were compared to 38 controls without SARS-CoV-2 infection (26 female, 10.3 ± 3.4 years, n = 15 with other infection within last 6 months). After standardised interviews and neurological examinations, large fibre (tactile and vibration detection thresholds) and small fibre (cold and warm detection thresholds, paradoxical heat sensation) functions were assessed on both feet following a validated protocol. After z-transformation of all values, all participants were compared to published reference values regarding the number of abnormal results. Additionally, the mean for all sensory parameters values of both study groups were compared to an ideal healthy population (with z-value 0 ± 1), as well as with each other, as previously described. Statistical analyses: t-test, Chi-squared test, and binominal test.

Findings

None of the controls, but 27 of the 81 patients (33%, p < 0.001) reported persistent complaints 2.7 ± 1.9 (0.8-8.5) months after SARS-CoV-2 infection, most often reduced exercise capacity (16%), fatigue (13%), pain (9%), or paraesthesia (6%). Reflex deficits or paresis were missing, but somatosensory profiles showed significantly increased detection thresholds for thermal (especially warm) and vibration stimuli compared to controls. Approximately 36% of the patients after SARS-CoV-2, but none of the controls revealed an abnormal sensory loss in at least one parameter (p < 0.01). Sensory loss was characterised in 26% by large and 12% by small fibre dysfunction, the latter appearing more frequently in children with prior symptomatic SARS-CoV-2 infection. Myalgia/paraesthesia was indicative of somatosensory dysfunction. In all eight re-examined children, the nerve function recovered after 2-4 months.

Interpretation

This study provides evidence that in a subgroup of children and adolescents previously infected with SARS-CoV-2, regardless of their complaints, the function of large or small nerve fibres is presumably reversibly impaired.

Influenza A Virus Causes Histopathological Changes and Impairment in Functional Activity of Blood Vessels in Different Vascular Beds

It has been established that blood vessels are a target for influenza virus; however, the mechanism by which virus affects the cardiovascular system remains unknown. The aim of the study is the identification of histological changes and changes in the functional activity of the pulmonary and mesenteric blood vessels of Wistar rats. Wistar rats were intranasally infected with the influenza A(H1N1)pdm09 virus. At 24 and 96 h post infection (hpi), histopathological changes were observed in lung tissues with the absence of histological changes in mesenteric tissues. The functional activity of pulmonary and mesenteric arteries was determined using wire myography. In pulmonary arteries, there was a tendency towards an increase in integral response to the vasodilator and a decrease in the integral response to the vasoconstrictor at 24 hpi (compared with control). At 96 hpi, a tendency towards a decrease in the integral response to the vasoconstrictor persisted, while the response to acetylcholine was slightly increased. The functional activity of the mesenteric blood vessels was inverted: a significant decrease in the integral response to the vasodilator and an increase in the response to the vasoconstrictor at 24 hpi were observed; at 96 hpi, the integral response to the vasoconstrictor persisted, while the response to the vasodilator remained significantly reduced. Obtained data indicate the development of endothelial dysfunction in non-lethal and clinically non-severe experimental influenza virus infection.

Extensive Longitudinal Transverse Myelitis after Influenza A Virus Infection in a Patient with Systemic Lupus Erythematosus

Transverse myelitis (TM) is a rare complication seen in 1–2% of patients with systemic lupus erythematosus (SLE). Viral infections may cause TM in these patients by causing a dysregulation of their immune system. We report a 30-year-old woman with SLE who had influenza A and a few days later developed urinary retention, bilateral lower extremity paralysis, upper extremity weakness, and optic nerve and macular edema. Magnetic resonance imaging showed C4-T12 hyperintense lesions consistent with TM. She was treated with intravenous methylprednisolone 1 g daily for 3 days and then 6 cycles of monthly intravenous cyclophosphamide. This treatment was followed by oral prednisone. She had a remarkable clinical response. Visual acuity improved to her baseline, and muscle strength almost fully recovered. Clinicians should be aware that viral infections, including influenza, may induce TM. This case highlights the importance of early recognition and prompt treatment with immunosuppressive drugs in such cases.

Infection and Immunometabolism in the Central Nervous System: A Possible Mechanistic Link Between Metabolic Imbalance and Dementia

Metabolic syndromes are frequently associated with dementia, suggesting that the dysregulation of energy metabolism can increase the risk of neurodegeneration and cognitive impairment. In addition, growing evidence suggests the link between infections and brain disorders, including Alzheimer's disease. The immune system and energy metabolism are in an intricate relationship. Infection triggers immune responses, which are accompanied by imbalance in cellular and organismal energy metabolism, while metabolic disorders can lead to immune dysregulation and higher infection susceptibility. In the brain, the activities of brain-resident immune cells, including microglia, are associated with their metabolic signatures, which may be affected by central nervous system (CNS) infection. Conversely, metabolic dysregulation can compromise innate immunity in the brain, leading to enhanced CNS infection susceptibility. Thus, infection and metabolic imbalance can be intertwined to each other in the etiology of brain disorders, including dementia. Insulin and leptin play pivotal roles in the regulation of immunometabolism in the CNS and periphery, and dysfunction of these signaling pathways are associated with cognitive impairment. Meanwhile, infectious complications are often comorbid with diabetes and obesity, which are characterized by insulin resistance and leptin signaling deficiency. Examples include human immunodeficiency virus (HIV) infection and periodontal disease caused by an oral pathogen Porphyromonas gingivalis. This review explores potential interactions between infectious agents and insulin and leptin signaling pathways, and discuss possible mechanisms underlying the relationship between infection, metabolic dysregulation, and brain disorders, particularly focusing on the roles of insulin and leptin.

Acceptance of COVID-19 vaccination and correlated variables among global populations: A systematic review and meta-analysis

Introduction

The most awaited solution is an efficient COVID-19 vaccine. COVID-19 vaccine acceptance has not been studied in a meta-analysis. The objective of this research was to find the acceptance of COVID-19 vaccination and correlated variables.

Methods

A systematic review of studies on acceptance of COVID-19 vaccination and correlated variables in the ProQuest, PubMed, and EBSCO to find relevant articles published between January 2020 and March 2021. Using fixed and random-effect models, the risk factors Pooled Odds Ratio (POR) were measured. The heterogeneity was calculated using the I-squared formula. Egger's and Begg's tests were utilised to determine publication bias. STATA 16.0 was used for all data processing and analysis.

Results

This study results showed the related factors for COVID-19 vaccination acceptance, high income has the highest odd ratio (POR = 2.36), followed by encountered with COVID-19 (POR = 2.34), fear about COVID-19 (POR = 2.07), perceived benefits (POR = 1.81), flu vaccine during the previous season (POR = 1.69), healtcare workers (POR = 1.62), male (POR = 1.61), married (POR = 1.59), perceived risk (POR = 1.52), trust in health system (POR = 1.52), chronic diseases (POR = 1.47), high education (POR = 1.46), high level of knowledge (POR = 1.39), female (1.39), and older age (POR = 1.07). The heterogeneity calculation showed homogenous among studies in high income, fear about COVID-19, healthcare workers, married, chronic diseases, and female (I² ≤ 50%). For the studies included in this review, there was no apparent publication bias.

Conclusion

The analysis of this review may be useful to the nation in determining the best method for implementing COVID-19 mass vaccination programs based on relevant factors that influence vaccine acceptance.

Influenza Vaccination for the Prevention of Cardiovascular Disease in the Americas: Consensus document of the Inter-American Society of Cardiology and the Word Heart Federation

Background

Cardiovascular mortality is decreasing but remains the leading cause of death world-wide. Respiratory infections such as influenza significantly contribute to morbidity and mortality in patients with cardiovascular disease. Despite of proven benefits, influenza vaccination is not fully implemented, especially in Latin America.

Objective

The aim was to develop a regional consensus with recommendations regarding influenza vaccination and cardiovascular disease.

Methods

A multidisciplinary team composed by experts in the management and prevention of cardiovascular disease from the Americas, convened by the Inter-American Society of Cardiology (IASC) and the World Heart Federation (WHF), participated in the process and the formulation of statements. The modified RAND/UCLA methodology was used. This document was supported by a grant from the WHF.

Results

An extensive literature search was divided into seven questions, and a total of 23 conclusions and 29 recommendations were achieved. There was no disagreement among experts in the conclusions or recommendations.

Conclusions

There is a strong correlation between influenza and cardiovascular events. Influenza vaccination is not only safe and a proven strategy to reduce cardiovascular events, but it is also cost saving. We found several barriers for its global implementation and potential strategies to overcome them.

Spatial learning and memory impaired after infection of non-neurotropic influenza virus in BALB/c male mice

During the influenza pandemic or seasonal influenza outbreak, influenza infection can cause acute influenza-associated encephalopathy/encephalitis (IAE), even death. Patients with severe IAE will also have severe neurological sequelae. Neurologic disorders have been demonstrated in the mice treated with peripheral influenza viruses infection, whether neurotropic or non-neurotropic viruses. However, previous studies focused on the acute phase of infection, and rarely paid attention to a longer range of observations. Therefore, the long-term effect of non-neurotropic virus infection on the host is not very clear. In this study, adult mice were infected with influenza virus H1N1/PR8. Then, spontaneous behavior, body weight, expression of cytokines in brain, spatial learning ability and spatial memory ability were observed, until the complete recovery period. The results showed that cytokines in the brain were highly expressed in the convalescent phase (14 day post inoculation, dpi), especially BDNF, IBA1, CX3CL1 and CD200 were still highly expressed in the recovery phase (28 dpi). Otherwise the emotional and spatial memory ability of mice were impacted in the convalescent phase (14 dpi) and the recovery phase (28 dpi). In brief, BALB/c mice infected with non-neurotropic influenza virus H1N1, the weight and motor ability decreased in acute stage. During the recovery period, the body weight and activity ability were completely restored, whereas the emotion disordered, and the ability of spatial learning and memory were impacted in the infected mice. This long-term behavior impact may be the lag injury caused by non-neurotropic influenza infection.

Neurological complications of pandemic A(H1N1)2009pdm, postpandemic A(H1N1)v, and seasonal influenza A

OBJECTIVES

Not much is known about influenza-associated neurological complications. We aimed to describe the case series of hospitalized patients who were confirmed with influenza A and presented with neurological symptoms in order to capture the broad spectrum of influenza clinical manifestation and suggest including influenza diagnostic in some neurological conditions.

MATERIALS AND METHODS

The inclusion criteria were age ≥ 18 and laboratory-confirmed influenza presenting with neurological symptoms. Influenza-associated neurological complication was described as a development of neurological symptom with no other origin. The outcomes were classified into 5 categories: 1. recovery with no significant disability; 2. minor disability (able to manage on their own); 3. moderate disability (requiring some help but able to walk without assistance); 4. severe disability (unable to walk without assistance and perform daily activities); 5. death.

RESULTS

In total, 12 patients (five women and seven men) were enrolled, with age range 18-71 years old. Neurological complications of pandemic A(H₁ N₁ )2009pdm influenza developed in seven out of 69 (10.1%) hospitalized patients. The most common neurological complication was encephalopathy. Neurological complications developed in two out of 24 (8.3%) hospitalized patients during postpandemic (H₁ N₁ )_V period. One patient presented with encephalopathy, another with meningoencephalitis. During the 2018 influenza season, there was one patient who has developed influenza A neurological complications. Overall, two out of 104 (1.9%) influenza A patients developed influenza-associated neurological complications in 2019.

CONCLUSIONS

Every patient with unexplained neurological symptoms and signs similar to aseptic and septic meningitis/encephalitis has to be tested for influenza virus during epidemics and pandemics.

Neuroethical and Societal Challenges of 21st Century Epidemics

Neurologic and neuropsychiatric manifestations of COVID-19 are affecting a growing number of people worldwide. We provide a brief overview of these manifestations, contrasting them with those of other 21st century viral epidemics, as well as mitigation strategies, and societal and moral considerations related to the pandemic. We highlight unique concerns relating to COVID-19 given the scale of infection, mental health challenges faced by health care providers and the general public, and the unprecedented social consequences, including benefits and possible harms associated with continuous connectedness using modern digital communication.

A range of new ethical concerns accompanies the neurological and neuropsychiatric manifestations of COVID-19 compared with neuro-related symptoms and sequelae of past 21st century viral epidemics and pandemics.

The unique concerns of COVID-19 can be attributed to the scale of infection, mental health impacts, and access to digital communication technology.

Anxiety associated with the ethical and moral complexities of caring for patients, triaging them during a pandemic, and anticipating surges in cases may be as detrimental to the mental well-being of frontline health care workers as post-traumatic stress.

Previous recommendations for use of digital technology, especially among children, are being reconsidered in light of the demands for remote school, work, and socialization during the pandemic.

Monoclonal antibody against H1N1 influenza virus hemagglutinin cross reacts with hnRNPA1 and hnRNPA2/B1

Following influenza A vaccination, certain individuals exhibit adverse reactions in the nervous system, which causes a problem with the safety of the influenza A vaccine. However, to the best of our knowledge, the underlying mechanism of this is unknown. The present study revealed that a monoclonal antibody (H1‑84mAb) against the H1N1 influenza virus hemagglutinin (HA) protein cross‑reacted with an antigen from brain tissue. Total brain tissue protein was immunoprecipitated with this cross‑reactive antibody, and mass spectrometry revealed that the bound antigens were heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and hnRNPA2/B1. Subsequently, the two proteins were expressed in bacteria and it was demonstrated that H1‑84mAb bound to hnRNPA1 and hnRNPA2/B1. These two proteins were expressed in three segments and the cross‑reactivity of H1‑84mAb with the glycine (Gly)‑rich domains of hnRNPA1 (195aa‑320aa) and hnRNPA2/B1 (202aa‑349aa) was determined using ELISA blocking experiments. It was concluded that the Gly‑rich domains of these two proteins are heterophilic antigens that cross‑react with influenza virus HA. The association between the heterophilic antigen Gly‑rich domains and the safety of influenza A vaccines remains to be investigated.

Neurologic Complications in Children Hospitalized With Influenza Infections: Prevalence, Risk Factors and Impact on Disease Severity

BACKGROUND

Influenza infection is a common cause of respiratory disease and hospitalization in children. Neurologic manifestations of the infection have been increasingly reported and may have an impact on the severity of the disease. The aim of this study is to describe neurologic events in pediatric patients hospitalized with influenza and identify associated risk factors.

METHODS

Retrospective cohort study which included all hospitalized patients with microbiologic confirmation of influenza disease over 4 epidemic seasons, focusing on neurologic complications. Demographic, laboratory and clinical data, as well as past history, were recorded. Descriptive and analytic statistical study was performed using SPSS and R statistical software.

RESULTS

Two hundred forty-five patients were included. Median age was 21 months (interquartile range, 6-57) and 47.8% had a previous underlying condition. Oseltamivir was administered to 86% of patients, median hospitalization was 4 days (interquartile range, 3-6), and pediatric intensive care unit admission rate 8.9%. Twenty-nine patients (11.8%) developed neurologic events, febrile seizures being the most frequent, followed by nonfebrile seizures and encephalopathy. Status epilepticus occurred in 4 children, and 69.6% of seizures recurred. Patients with a previous underlying condition were at greater risk of developing a neurologic complication [odds ratio (OR), 4.55; confidence interval (CI), 95% 1.23-16.81). Male sex (OR, 3.21; CI 95%, 1.22-8.33), influenza B virus (OR, 2.82; CI 95%, 1.14-7.14) and neurologic events (OR, 3.34; CI 95%, 1.10-10.19) were found to be risk factors for pediatric intensive care unit admission.

CONCLUSIONS

A significant proportion of influenza-related hospitalized patients develop neurologic complications, especially seizures which may be prolonged or recurrent. Previous underlying conditions pose the greatest risk to neurologic events, which increase disease severity.

Neurological complications associated with influenza in season 2017/18 in Austria- a retrospective single center study

BACKGROUND

Neurological complications associated with influenza (NCI) are rare events in adults with seasonal influenza. Information about the characteristics of neurological complications and the burden of disease has been limited to case reports, mainly during the pandemic 2009. Influenza-associated encephalopathy/encephalitis (IAE) is one of the most severe and frequently reported NCI, mostly caused by influenza A. Isolated case reports exist about NCI caused by influenza B.

OBJECTIVES

The aim of this single center retrospective study is the better understanding of the frequency and the characteristics of NCI in adults in season 2017-2018, depending on the influenza subtype A or B.

STUDY DESIGN

We reviewed 874 adult patients with laboratory confirmed influenza admitted to the Christian Doppler University Hospital Salzburg, Austria from December 2017 until March 2018 looking for NCI.

RESULTS

37 (4 %) of the 874 patients with confirmed influenza had NCI. 4 (11 %) had influenza A and 33 (89 %) had influenza B. IAE was the most frequent complication diagnosed in 24 (65 %) patients, of whom all but one had influenza B and 3 (13 %) had neurological residuals. Moreover 6 (16 %) had isolated epileptic seizures, 2 (5 %) had acute inflammatory demyelinating polyneuropathy (AIDP), and 5 (14 %) were classified as having infection-associated stroke.

CONCLUSIONS

We report an incidence of 4 % for NCI and a high frequency of IAE caused by subtype B. Therefore, we recommend considering both influenza A and B as an etiologic factor of encephalopathy and other neurological disease in adults.

Serious infection may systemically increase noradrenergic signaling and produce psychological effects

Serious infection elicits inflammatory processes that act through a range of molecular pathways, including cytokine signaling. It is not established however that noradrenaline (NA), a widely distributed neurotransmitter in the brain that is also a principal output molecule of the sympathetic nervous system, can produce psychological effects associated with infection. This paper puts forth the hypothesis that through neural-immune crosstalk, serious infection increases noradrenergic signaling, both in the central nervous system and in peripheral organs. In this manner, elevated noradrenergic transmission may help produce basic symptoms of infection such as fever, fatigue, aches and pains (including headache), nausea, and loss of appetite. NA may also promote cognitive impairment, major depression, unipolar mania, and even epileptic seizures in some cases. The paper focuses on three major types of infection: influenza (viral), tuberculosis (bacterial), malaria (parasitic), while also summarizing the potential relationship between NA and human immunodeficiency virus (HIV) infection. Four lines of evidence are used to test association between NA and influenza, tuberculosis, and malaria: direct measures of NA and its metabolites; and incidence of hypertension, bipolar mania, and epileptic seizures, since the latter three conditions may be associated with elevated NA. In addition, heart rate variability data are examined with respect to a number of infectious diseases, since those data provide information on sympathetic nervous system activity. While the data do not unequivocally support elevated noradrenergic signaling promoting psychological symptomatology with infection, many studies are consistent with this view.

Muscle weakness associated with H7N9 infection: report of two cases

Background

The emerging avian influenza A (H7N9) virus, a subtype of influenza viruses, was first discovered in March 2013 in China. Infected patients frequently present with pneumonia and acute respiratory disorder syndrome with high rates of intensive care unit admission and death. Neurological complications, such as Guillain–Barré syndrome(GBS), and intensive care unit-acquired weakness, including critical illness polyneuropathy and myopathy, have only rarely been reported previously.

Case presentation

In this study, we report on two Chinese patients with H7N9 severe pneumonia presenting neurological complications. These two patients had non-immune diseases prior to the onset of virus infection. A 56-year-old female patient (case 1) and a 78-year-old female patient (case 2) were admitted because of fever, cough, chest tightness and shortness of breath. These patients were confirmed to have H7N9 infection soon after admission followed by the development of acute respiratory distress syndrome and various severe bacterial and fungal infections. The case 1 patient was found to have muscle weakness in all extremities after withdrawing the mechanical ventilator, and the case 2 patient was found when withdrawing extracorporeal membrane oxygenation, both of these conditions prolonged ventilator-weaning time. Furthermore, the case 1 patient carried the H7N9 virus for a prolonged period, reaching 28 days, and both of them stayed in the hospital for more than two months. A clinical diagnosis of intensive care unit-acquired weakness could be confirmed. However, based on results from electrophysiological testing and needle electromyography of these 2 patients, it is difficult to differentiate critical illness polyneuropathy from GBS, since no lumbar puncture or muscle and nerve biopsy were conducted during hospitalization. Following a long-term comprehensive treatment, the patients’ neurological condition improved gradually.

Conclusions

Although there is great improvement in saving severe patients’ lives from fatal respiratory and blood infections, it is necessary to pay sufficient attention and to use more methods to differentiate GBS from intensive care unit-acquired weakness. This unusual neurological complication could result in additional complications including ventilator associated pneumonia, prolonged hospital stay and then would further increase the death rate, and huge costs.

The Spectrum and Burden of Influenza-Associated Neurological Disease in Children: Combined Encephalitis and Influenza Sentinel Site Surveillance From Australia, 2013-2015

Background

There are few longitudinal studies of seasonal influenza-associated neurological disease (IAND) and none from the Southern Hemisphere.

Methods

We extracted prospectively acquired Australian surveillance data from 2 studies nested within the Paediatric Active Enhanced Disease Surveillance (PAEDS) network: the Influenza Complications Alert Network (FluCAN) study and the Australian Childhood Encephalitis (ACE) study between 2013 and 2015. We described the clinical features and severity of IAND in children, including influenza-associated encephalitis/encephalopathy (IAE). We calculated the proportion of hospitalized influenza that is associated with IAND and IAE, and incidence of IAE.

Results

Over 3 influenza seasons, we identified 54 cases of IAND at 2 tertiary children's hospitals from Australia that accounted for 7.6% of hospitalized influenza. These included 10 cases of IAE (1.4% hospitalized influenza). The mean annual incidence of IAE among Australian children (aged ≤14 years) was 2.8 per 1000000. The spectrum of IAND was broad and included IAE (n = 10) including distinct acute encephalopathy syndromes, simple febrile seizures (n = 14), other seizures (n = 16), acute ataxia (n = 4), and other subacute syndromes (transverse myelitis [n = 1], opsoclonus myoclonus [n = 1]). Two-thirds of children with IAND were aged ≤4 years; less than half had preexisting neurological disease or other risk factors for severe influenza. IAE caused death or neurological morbidity in half of cases.

Conclusions

Seasonal influenza is an important cause of acute neurological disease in Australian children. The spectrum of seasonal IAND appears similar to that described during the 2009 H1N1 pandemic. IAE is associated with high morbidity and mortality.

A rare case of influenza A in a hospitalized adult presenting with encephalitis and a seizure

Influenza A in hospitalized adults uncommonly may present with neurologic manifestations, e.g., encephalitis. Encephalitis is the most common influenza related neurologic complication in adults, However, seizures in hospitalized adults due to influenza are extremely rare. This is a case of a 58 year old female hospitalized for influenza A. On admission, she was confused and obtunded. Her EEG showed diffuse global slowing indicative of encephalitis. On hospital day (HD) #2, she had a seizure. She had no history of a seizure disorder, and was not febrile at the time of the seizure. While seizures are not uncommon in children (febrile seizures) with influenza B, but in adults with influenza A, only a few cases of seizures have been reported. This case was most interesting in having both encephalitis and seizure complicating influenza A. If present, neuropsychiatric manifestations may be due to ostelamivir, but encephalitis and seizures are not among the neurologic adverse effects of ostelamivir. In adults hospitalized with influenza A, clinicians should be alert to the possibility of neurologic complications.

Neurologic Complications of Influenza B Virus Infection in Adults, Romania

We characterized influenza B virus-related neurologic manifestations in an unusually high number of hospitalized adults at a tertiary care facility in Romania during the 2014-15 influenza epidemic season. Of 32 patients with a confirmed laboratory diagnosis of influenza B virus infection, neurologic complications developed in 7 adults (median age 31 years). These complications were clinically diagnosed as confirmed encephalitis (4 patients), possible encephalitis (2 patients), and cerebellar ataxia (1 patient). Two of the patients died. Virus sequencing identified influenza virus B (Yam)-lineage clade 3, which is representative of the B/Phuket/3073/2013 strain, in 4 patients. None of the patients had been vaccinated against influenza. These results suggest that influenza B virus can cause a severe clinical course and should be considered as an etiologic factor for encephalitis.

Influenza-associated seizures in healthy adults: Report of 3 cases

To describe seizures occurring in 3 healthy adults with influenza infection. Seizures associated to influenza infection are rare in adults without encephalitis. Clinical observations of 3 healthy adult patients with influenza A and B infection and seizures. We present here 3 healthy adult patients with seizures related to influenza A or B infection without evidence encephalitis, encephalopathy or any other cause for seizures. Prognosis was excellent. Seizures can occur in healthy adults with influenza infection without evidence of encephalitis, a possibility to be borne in mind to avoid potentially harmful therapeutic and diagnostic procedures.

Pandemic H1N1 Vaccination and Incidence of Acute Disseminated Encephalomyelitis in Manitoba

Background: An increased incidence of hospital admissions coded as acute disseminated encephalomyelitis (ADEM) was noted in Winnipeg, Manitoba, Canada, during the second wave of the influenza pandemic from October 2009 to March 2010. However, it was not clear whether this was due to heightened awareness of potential neurological complications of influenza or influenza vaccination or an actual increase in the number of cases. Methods: We extracted data from the charts of 139 patients hospitalized with an International Classification of Diseases-10 discharge code indicating ADEM (G04.0) or unspecified noninfectious encephalitis or myelitis (G04.8, G04.9) between January 2006 and December 2012. Clinical and laboratory data were reviewed by a neurologist, and diagnoses were determined using the Brighton criteria. Results: Over the entire study period, there were 22 cases of ADEM. During the peak pandemic period (April-December 2009), seven patients were hospitalized with ADEM, corresponding to a rate of 7.8/million/year; 4.7 (95% confidence interval: 1.9-11.4) times higher than the rate before or after the pandemic period. Only one patient with ADEM had received the monovalent A(H1N1)pdm09 vaccine within 12 weeks of hospitalization. Conclusions: We have found an increased incidence of ADEM during the pandemic period that may be related, at least in part, to the increased incidence of influenza during that period. However, there was no temporal relationship with the administration of A(H1N1)pdm09 or seasonal influenza vaccines. Our study provides reassurance that use of these vaccines was not associated with increased risk of ADEM.

Did exposure to a severe outbreak of pandemic influenza in 1918 impact on long-term survival?

There is some suggestion that infection with pandemic influenza may increase long-term mortality risks. Therefore we aimed to determine if exposure to a severe outbreak of pandemic influenza on a troopship in 1918 impacted on lifespan in the survivors. The troopship with the outbreak cohort had 1107 personnel and the comparison cohort was from two contemporaneous troopships (1108 randomly selected personnel). Data were collected from online individual military files. The main finding was that there was no statistically significant difference in the lifespan of the outbreak cohort and the comparison cohort (means of 71·5 and 71·0 years, respectively). Indeed, the outbreak cohort was actually more likely to survive into the period from 1950 onwards (P = 0·036) and to participate in the Second World War (P = 0·043). There were no significant differences between the cohorts in terms of occupational class, but the comparison cohort had a higher proportion of rural occupations (33·3% vs. 27·0%, P < 0·001) and was very slightly older in mid-1918 (27·8 vs. 27·2 years, P = 0·028). In conclusion, this study found no support for the hypothesis that exposure to the 1918 influenza pandemic adversely impacted on the lifespan in the survivors, at least in this male and military-age population.

Seasonal Influenza Epidemics and El Niños

Seasonal influenza epidemics occur annually during the winter in the northern and southern hemispheres, but timing of peaks and severity vary seasonally. Low humidity, which enhances survival and transmission of influenza virus, is the major risk factor. Both El Niño and La Niña phases of El Niño-southern oscillation (ENSO), which determine inter-annual variation of precipitation, are putative risk factors. This study was done to determine if seasonality, timing of peak, and severity of influenza epidemics are coupled to phases of ENSO. Monthly time series of positive specimens for influenza viruses and of multivariate El Niño-Southern Oscillation Index from January 2000 to August 2015 were analyzed. Seasonality, wavelet spectra, and cross-wavelet spectra analyses were performed. Of 31 countries in the dataset, 21 were in the northern hemisphere and 10 in the southern hemisphere. The highest number of influenza cases occurred in January in the northern hemisphere, but in July in the southern hemisphere, p < 0.0001. Seasonal influenza epidemic was coupled to El Niño, while low occurrence was coupled to La Niña. The moderate La Niña of 2010-2011 was followed by weak seasonal influenza epidemic. The influenza pandemic of 2009-2010 followed the moderate El Niño of 2009-2010, which had three peaks. Spectrograms showed time-varying periodicities of 6-48 months for ENSO, 6-24 months for influenza in the northern hemisphere, and 6-12 months for influenza in the southern hemisphere. Cross spectrograms showed time-varying periodicities at 6-36 months for ENSO and influenza in both hemispheres, p < 0.0001. Phase plots showed that influenza time series lagged ENSO in both hemispheres. Severity of seasonal influenza increases during El Niño, but decreases during La Niña. Coupling of seasonality, timing, and severity of influenza epidemics to the strength and waveform of ENSO indicate that forecast models of El Niño should be integrated into surveillance programs for influenza epidemics.

Severe post-influenza (H1N1) encephalitis involving pulvinar nuclei in an adult patient

Neurological complications of H1N1 infections are mostly found in children, but rare cases of acute encephalopathy and post-infectious encephalitis such as acute disseminated encephalomyelitis (ADEM) have been described in adults. We report a case of an adult presenting with a progressive and severe encephalopathy that developed after H1N1 respiratory infection resolution. Cerebrospinal fluid (CSF) analysis was normal, including negative PCR for herpes simplex virus, H1N1, influenza B and JC virus, and absent oligoclonal IgG bands in CSF and serum. Initial CT scan was normal, but later MRI showed posterior multifocal leucoencephalopathy with pulvinar sign. The delayed neurological findings together with the ancillary investigation, namely the MRI pattern with both grey and white matter involvement, raised the possibility of a post-infectious process, rather than an acute encephalitis. Despite aggressive immunotherapy, the patient experienced severe neurological sequelae. Early recognition of ADEM manifestations by those dealing with H1N1 infection is important as early immunotherapy may improve the prognosis.