Characteristics and Outcomes of Influenza-Associated Encephalopathy Cases Among Children and Adults in Japan, 2010-2015

Incidence of Influenza-associated Neurologic and Psychiatric Complications Requiring Hospitalization in Children Ages 5-17 Years

BACKGROUND

The spectrum and incidence of influenza-associated neuropsychiatric complications are not well-characterized. The objective of this study was to define the incidence of specific neurologic and psychiatric complications associated with influenza in children and adolescents.

METHODS

We assembled a retrospective cohort of children 5-17 years of age with an outpatient or emergency department International Classification of Diseases, 10th revision influenza diagnosis and enrolled in Tennessee Medicaid from 2016 to 2020. Serious neurologic or psychiatric complications requiring hospitalization were identified using a validated algorithm. Incidence rates of complications were expressed per 100,000 person-weeks of influenza and 95% confidence intervals (CIs) were reported.

RESULTS

A total of 156,611 influenza encounters (median age of 9.3 years) were included. The overall incidence of neurologic complications was 30.5 (95% CI: 24.0-38.6) per 100,000 person-weeks of influenza and 1880.9 (95% CI: 971.9-3285.5) among children with an underlying neurologic comorbidity. The distribution of antiviral treatment was similar among those with and without neurologic or psychiatric complications. The overall incidence of psychiatric complications was 20.2 (95% CI: 15.1-27.0) per 100,000 person-weeks of influenza and 111.8 (95% CI: 77.9-155.5) among children with an underlying psychiatric comorbidity. Seizures (17.5, 95% CI: 12.8-23.9) were the most common neurologic complications whereas encephalitis (0.5, 95% CI: 0.02-2.5) was rare. Mood disorders (17.5, 95% CI: 12.8-23.9) were the most frequent psychiatric complications and self-harm events (0.9, 95% CI: 0.3-3.3) were the least common.

DISCUSSION

Our findings reveal that the incidence of neuropsychiatric complications of influenza is overall low; however, the incidence among children with underlying neurologic or psychiatric condition is significantly higher than among children without these conditions.

Clinical characteristics and genetic analysis of children with Omicron BF.7.14 type novel coronavirus-related acute necrotizing encephalopathy

Background

To explore the clinical characteristics, etiological factors, and clinical-related genetic variant of children with acute necrotizing encephalopathy (ANE) related to the Omicron BF.7.14 novel coronavirus.

Methods

Genomic variations were detected through whole exome sequencing. Additionally, we summarized the clinical data to explore the inheritance patterns associated with novel coronavirus-related ANE.

Results

This study included four patients (2 males and 2 females) with an average age of 2.78 ± 1.93 years. All the patients had prodromal symptoms of Omicron BF.7.14 virus infection, and exhibited symptoms such as altered consciousness, seizures and cognitive/language disturbances. Cranial MRI scans revealed damage to the thalamus, basal ganglia and brainstem. The cerebrospinal fluid (CSF) cell counts were nearly normal, but protein level in CSF increased significantly. Genetic analysis revealed a novel truncated variant of CRMP2 gene in one patient who suffered more severe coma score and prognosis and dead in the later stages. All children exhibited a decrease in the absolute count of T lymphocytes, helper T cells, suppressor T cells, and NK cells to varying degrees. Furthermore, levels of cytokines, including IL-1 β, IL-5, IL-6 and IL-8 were significantly elevated in the CSF, especially in patient with truncated variant of CRMP2 gene.

Conclusion

The Omicron BF.7.14 type novel coronavirus can lead to ANE, characterized by T cell immunosuppression and a significant increase in cytokine levels in the CSF. The truncated variation of CRMP2 gene may affect the prognosis of ANE by affecting the migration of cerebral T cells.

Neurological involvement related to the influenza virus in children: A 5-year single-centre retrospective study

INTRODUCTION

Inflammation related to influenza virus infection can lead to multiple neurological presentations. Encephalitis is one of them, mostly accompanied by seizures, with different profiles depending on the epidemics and previous medical conditions.

MATERIALS AND METHODS

All children presenting neurological symptoms and positive for influenza virus RNA detection in a respiratory sample between November 2018 and April 2023, hospitalized in the Department of Paediatric Neurology of Toulouse Children's Hospital, were retrospectively analysed.

RESULTS

Among the 1,277 children diagnosed with influenza in our centre, 131 (10.3 %) were hospitalized for neurological features. The year 2020-2021 was marked by zero incidence of positive influenza tests, associated with the COVID-19 pandemic. Among the 131 patients included, 71.6 % were under 5 years old. Most of them (80.9 %) were infected by influenza A virus. The first neurological symptoms were mainly seizures in 73.3 % of patients. Possible or confirmed encephalitis was observed in 29 % of cases, including one acute necrotizing encephalopathy. Few children (6.1 %) presented with acute myositis. Twenty-seven patients (20.6 %) had a personal history of significant previous neurological disorders. Most patients (88.5 %) displayed a rapid favourable outcome, marked by the disappearance of their neurological symptoms within the first 2 days. Anti-epileptic drugs were introduced in 1.5 % of cases, and adapted in 16.8 %, mainly in patients with febrile status epilepticus and an abnormal EEG.

CONCLUSION

Neurological features were frequently associated with influenza infection in children; most were transient. Effects on long-term neurodevelopmental outcomes need to be clarified as our follow-up was limited, especially in children with pre-existing neurological conditions.

Viral entry and translation in brain endothelia provoke influenza-associated encephalopathy

Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza virus in this acute phase in the brain is largely unknown. Here we show that influenza virus enters into the cerebral endothelium and thereby induces IAE. Three-weeks-old young mice were inoculated with influenza A virus (IAV). Physical and neurological scores were recorded and temporal-spatial analyses of histopathology and viral studies were performed up to 72 h post inoculation. Histopathological examinations were also performed using IAE human autopsy brains. Viral infection, proliferation and pathogenesis were analyzed in cell lines of endothelium and astrocyte. The effects of anti-influenza viral drugs were tested in the cell lines and animal models. Upon intravenous inoculation of IAV in mice, the mice developed encephalopathy with brain edema and pathological lesions represented by micro bleeding and injured astrocytic process (clasmatodendrosis) within 72 h. Histologically, massive deposits of viral nucleoprotein were observed as early as 24 h post infection in the brain endothelial cells of mouse models and the IAE patients. IAV inoculated endothelial cell lines showed deposition of viral proteins and provoked cell death, while IAV scarcely amplified. Inhibition of viral transcription and translation suppressed the endothelial cell death and the lethality of mouse models. These data suggest that the onset of encephalopathy should be induced by cerebral endothelial infection with IAV. Thus, IAV entry into the endothelium, and transcription and/or translation of viral RNA, but not viral proliferation, should be the key pathogenesis of IAE.

Brain Pathology in COVID-19: Clinical Manifestations and Potential Mechanisms

Neurological manifestations of coronavirus disease 2019 (COVID-19) are less noticeable than the respiratory symptoms, but they may be associated with disability and mortality in COVID-19. Even though Omicron caused less severe disease than Delta, the incidence of neurological manifestations is similar. More than 30% of patients experienced "brain fog", delirium, stroke, and cognitive impairment, and over half of these patients presented abnormal neuroimaging outcomes. In this review, we summarize current advances in the clinical findings of neurological manifestations in COVID-19 patients and compare them with those in patients with influenza infection. We also illustrate the structure and cellular invasion mechanisms of SARS-CoV-2 and describe the pathway for central SARS-CoV-2 invasion. In addition, we discuss direct damage and other pathological conditions caused by SARS-CoV-2, such as an aberrant interferon response, cytokine storm, lymphopenia, and hypercoagulation, to provide treatment ideas. This review may offer new insights into preventing or treating brain damage in COVID-19.

Seizures in Children with Influenza during the 2022-2023 Winter Season, a Case Series

Influenza is a viral infection presenting with general symptoms such as fever, headache, fatigue, and involvement of airways or the gastrointestinal tract. The nervous system may be involved, but less frequently. These neurological complications remain challenging to diagnose; moreover, no guidelines for management and treatment exist. Therefore, when presenting with neurological symptoms, patients undergo invasive diagnostic procedures and empirical treatments before making the correct diagnosis. During the winter of 2022-2023, four children between nine months and nine years of age were admitted to the Lausanne University Hospital, Switzerland, complaining of influenza and neurological complications. This report presents the symptoms of neurological manifestation and the treatment management of the four patients. All the legally authorized representatives gave their written informed consent before study inclusion.

Magnetic resonance imaging in acute meningoencephalitis of viral and unknown origin: frequent findings and prognostic potential

Background

Magnetic resonance imaging (MRI) findings in meningoencephalitis have mainly been described in terms of their diagnostic value rather than their prognostic potential, except for herpes simplex virus (HSV) encephalitis. The aims of our study were to describe frequency and anatomic locations of MRI abnormalities specific to limbic, circadian and motor systems in a cohort of meningoencephalitis patients, as well as to investigate the prognostic value of these MRI findings.

Methods

A secondary, selective analysis of a retrospective database including all meningitis, meningoencephalitis and encephalitis cases treated between 2016 and 2018 in the University hospital of Bern, Switzerland was performed. Patients with meningitis of any cause, bacterial or autoimmune causes of encephalitis were excluded.

Results

MRI scans and clinical data from 129 meningoencephalitis cases found that the most frequent causes were tick-borne encephalitis (TBE, 42%), unknown pathogens (40%), VZV (7%), and HSV1 (5%). At discharge, median modified Rankin Score (mRS) was 3 (interquartile range, IQR, 1), 88% of patients had persisting signs and symptoms. After a median of 17 months, median Glasgow Outcome Score (GOS) was 5 (IQR 1), 39% of patients still had residual signs or symptoms. All patients with HSV, 27% with TBE and 31% of those with meningoencephalitis of unknown etiology had fluid-attenuated inversion recovery (FLAIR) and to a lesser extent diffusion-weighted imaging (DWI) lesions in their initial MRI, with highly overlapping anatomical distribution. In one fifth of TBE patients the limbic system was affected. Worse outcome was associated with presence of DWI and/or FLAIR lesions and lower normalized apparent diffusion coefficient (ADC) signal intensities.

Conclusion

Presence of FLAIR lesions, restricted diffusion as well as the extent of ADC hypointensity in initial MRI are parameters which might be of prognostic value regarding the longterm clinical outcome for patients with meningoencephalitis of viral and of unknown origin. Although not described before, affection of limbic structures by TBE is possible as shown by our results: A substantial proportion of our TBE patients had FLAIR signal abnormalities in these regions.

Influenza H7N9 virus disrupts the monolayer human brain microvascular endothelial cells barrier in vitro

Influenza H7N9 virus causes human infections with about 40% case fatality rate. The severe cases usually present with pneumonia; however, some present with central nervous system complications. Pneumonia syndrome is attributed to the cytokine storm after infection with H7N9, but the pathogenic mechanism of central nervous system complications has not been clarified. This study used immortalized human brain microvascular endothelial cells hCMEC/D3 to simulate the blood-brain barrier. It demonstrated that H7N9 virus could infect brain microvascular endothelial cells and compromise the blood-brain barrier integrity and permeability by down-regulating the expression of cell junction-related proteins, including claudin-5, occludin, and vascular endothelial (VE)-cadherin. These results suggested that H7N9 could infect the blood-brain barrier in vitro and affect its functions, which could be a potential mechanism for the pathogenesis of H7N9 viral encephalopathy.

Risk factors for death associated with severe influenza in children and the impact of the COVID-19 pandemic on clinical characteristics

Background

To summarize the clinical features of severe influenza in children and the high-risk factors for influenza-related deaths and to raise awareness among pediatricians.

Methods

A retrospective study of clinical manifestations, laboratory tests, and diagnosis and treatment of 243 children with severe influenza admitted to Shenzhen Children's Hospital from January 2009 to December 2022 was conducted. Univariate logistic regression analysis and Boruta analysis were also performed to identify potentially critical clinical characteristics associated with death, and clinically significant were used in further multivariate logistic regression analysis. Subject receiver operating characteristic (ROC) curves were applied to assess the efficacy of death-related independent risk factors to predict death from severe influenza.

Results

There were 169 male and 74 female patients with severe influenza, with a median age of 3 years and 2 months and 77.4% of patients under six. There were 46 cases (18.9%) in the death group. The most common pathogen was Influenza A virus (IAV) (81.5%). The most common complication in the death group was influenza-associated acute necrotizing encephalopathy (ANE [52.2%]). Severe influenza in children decreased significantly during the COVID-19 pandemic, with a median age of 5 years, a high predominance of neurological symptoms such as ANE (P = 0.001), and the most common pathogen being H3N2 (P < 0.001). D-dimer, acute respiratory distress syndrome (ARDS), and acute necrotizing encephalopathy (ANE) were significant independent risk factors for severe influenza-associated death. Furthermore, the ROC curves showed that the combined diagnosis of independent risk factors had significant early diagnostic value for severe influenza-related deaths.

Conclusion

Neurological disorders such as ANE are more significant in children with severe influenza after the COVID-19 pandemic. Influenza virus infection can cause serious multisystem complications such as ARDS and ANE, and D-dimer has predictive value for early diagnosis and determination of the prognosis of children with severe influenza.

Bibliometric analysis of publication trends and topics of influenza-related encephalopathy from 2000 to 2022

BACKGROUND

Influenza-related encephalopathy is a rapidly progressive encephalopathy that usually presents during the early phase of influenza infection and primarily manifests as central nervous system dysfunction. This study aimed to analyze the current research status and hotspots of influenza-related encephalopathy since 2000 through bibliometrics analysis.

METHODS

The Web of Science Core Collection (WOSCC) was used to extract global papers on influenza-related encephalopathy from 2000 to 2022. Meanwhile, the VOSviewer and CiteSpace software were used for data processing and result visualization.

RESULTS

A total of 561 published articles were included in the study. Japan was the country that published the most articles, with 205 articles, followed by the United States and China. Okayama University and Tokyo Medical University published the most articles, followed by Nagoya University, Tokyo University, and Juntendo University. Based on the analysis of keywords, four clusters with different research directions were identified: "Prevalence of H1N1 virus and the occurrence of neurological complications in different age groups," "mechanism of brain and central nervous system response after influenza virus infection," "various acute encephalopathy" and "diagnostic indicators of influenza-related encephalopathy."

CONCLUSIONS

The research progress, hotspots, and frontiers on influenza-related encephalopathy after 2000 were described through the visualization of bibliometrics. The findings will lay the groundwork for future studies and provide a reference for influenza-related encephalopathy. Research on influenza-related encephalopathy is basically at a stable stage, and the number of research results is related to outbreaks of the influenza virus.

[Olfaction and respiratory viruses… A relationship revealed by Covid-19]

The sense of smell has been underestimated for a long time in humans. It has been brought to the fore by its sudden disappearance during the Covid-19 pandemic of which anosmia (complete loss of smell) is one of the major symptoms. However, respiratory viruses have long been associated with smell disorders, 25% of which are linked to a viral infection. Olfaction begins in the nose within the olfactory epithelium which has the particularity of containing neurons in direct contact with the environment. Several respiratory viruses are known for their replicative capacity within this epithelium. This is particularly the case for the flu virus (influenza) and bronchiolitis (respiratory syncytial virus) but their tropism for this tissue is much lower than SARS-CoV-2. The understanding of the SARS-CoV-2 pathophysiology in the nasal cavity makes it possible to reveal part of the links between viral infection and olfactory disorders.

Death in children with influenza A (H3N2) virus infection-associated encephalopathy: two case reports

We herein report two cases involving children who died of influenza A (H3N2) virus infection-associated encephalopathy/encephalitis (IAE). Both children developed convulsions and impaired consciousness within a relatively short period and eventually died of brainstem failure. Patient 1 presented with high fever, vomiting, and diarrhea. Laboratory tests indicated persistently high lactate, alanine aminotransferase, and urea nitrogen concentrations in the blood as well as a high protein concentration in the cerebrospinal fluid. Patient 2 presented with persistent hyperthermia and progressive disturbance of consciousness, but the cerebrospinal fluid remained normal during the disease course. Both patients were actively given oseltamivir antiviral treatment after diagnosis of influenza virus infection. However, the disease progressed and invasive mechanical ventilation was performed. Both children's condition quickly progressed to IAE, and they eventually died. IAE is a rare complication of influenza virus infection with high mortality, and its pathogenesis remains unclear. The purpose of this report is to draw attention to the serious central nervous system complications of influenza infection and raise awareness of the fatal consequences of this disease among pediatricians.

Severe Influenza-Associated Neurological Disease in Australian Children: Seasonal Population-Based Surveillance 2008-2018

BACKGROUND

Influenza-associated neurological disease (IAND) is uncommon but can result in death or neurological morbidity in children. We aimed to describe the incidence, risk factors, and outcome of children with IAND from seasonal influenza in Australia.

METHODS

We analyzed national, population-based, surveillance data for children aged ≤ 14 years with severe influenza and neurological involvement, over 11 Australian influenza seasons, 2008-2018, by the Australian Paediatric Surveillance Unit.

RESULTS

There were 633 laboratory-confirmed cases of severe influenza reported. Of these, 165 (26%) had IAND. The average annual incidence for IAND was 3.39 per million children aged ≤ 14 years. Compared to cases without neurological complications, those with IAND were more likely to have a pre-existing neurological disease (odds ratio [OR] 3.03, P < .001), but most children with IAND did not (n = 135, 82%). Children with IAND were more likely to receive antivirals (OR 1.80, P = .002), require intensive care (OR 1.79, P = .001), require ventilation (OR 1.99; P = .001), and die (OR 2.83, P = .004).

CONCLUSIONS

IAND is a preventable cause of mortality, predominantly in otherwise well children. Incidence estimates validate previous sentinel site estimates from Australia. IAND accounted for a quarter of all severe influenza, is associated with intensive care unit admission, and accounted for half of all influenza deaths.

Neurological complications associated with influenza in hospitalized children

BACKGROUND

Influenza is a known respiratory and potential neurotropic virus. This study aimed to determine the prevalence and outcomes of influenza-related neurological complications among hospitalized children.

METHODS

All medical records of hospitalized children aged <18 years old diagnosed with influenza at a tertiary care hospital in Bangkok were retrospectively reviewed. Influenza infection was confirmed by rapid antigen or reverse transcription polymerase chain reaction tests. Neurological characteristics and clinical outcomes were analyzed using the Pediatric Cerebral Performance Category Scale.

RESULTS

From 2013 to 2018, 397 hospitalized children with a median age of 3.7 years (interquartile range [IQR]: 1.6-6.9) were included. The prevalence of neurological complications, including seizure or acute encephalopathy, was 16.9% (95% confidence interval [CI]: 13.3-20.9). Influenza A and B were identified in 73.1% and 26.9% of the patients, respectively. Among 39 (58.2%) acute symptomatic seizure cases, 25 (37.3%) children had simple febrile seizures, 7 (10.4%) had repetitive seizures, and 7 (10.4%) had provoked seizures with pre-existing epilepsy. For 28 (41.8%) encephalopathy cases, the clinical courses were benign in 20 (29.9%) cases and severe in 8 (11.9%) cases. Ten (14.9%) children needed intensive care monitoring, and 62 (93.5%) fully recovered to their baselines at hospital discharge. Predisposing factors to the neurological complications included a history of febrile seizure (adjusted odds ratio [aOR]: 20.3; 95% CI: 6.6-63.0), pre-existing epilepsy (aOR: 3.6; 95% CI: 1.3-10.2), and a history of other neurological disorders (aOR: 3.5; 95% CI: 1.2-10.2).

CONCLUSIONS

One fifth of hospitalized children with influenza had neurological complications with a favorable outcome. Children with pre-existing neurological conditions were at higher risk for developing neurological complications.

Influenza-associated Neurologic Complications in Hospitalized Pediatric Patients: A Multicenter Retrospective Study in Republic of Korea

BACKGROUND

The rates of influenza-associated neurologic complications are variable among studies, and a difference has been observed between the Western and Asian countries. The study aims to evaluate the frequency and characteristics of influenza-associated neurologic complications.

METHODS

We performed a retrospective review of hospitalized cases of influenza infection from October 2010 to April 2017 from 3 referral hospitals.

RESULTS

A total of 1988 influenza cases were identified. Influenza-associated neurologic complications were 161 cases (8.1%); influenza virus A was detected in 113 (70.2%) cases, B in 47 (29.2%) cases and both A and B in 1 case (0.6%). Twenty-four patients (15%) had underlying neurologic diseases. The most common diagnosis was a simple febrile convulsion (44%), followed by complex febrile convulsion (29%), fever-provoked seizure under pre-existing neurologic disease or afebrile seizure (14%), encephalopathy/encephalitis (8%) and meningitis (5%). Most of the patients fully recovered (96%). Three patients (1.9%) died of myocarditis (n = 1), encephalopathy (n = 1), and simultaneous encephalitis and myocarditis (n = 1). Pre-existing neurologic disease, age groups of 6 months to 6 years and 6-12 years were a risk factor of influenza-associated neurologic complications with an adjusted odds ratio of 5.41 (95% confidence interval [CI] 3.23-9.06, P < 0.001), 12.99 (95% CI 1.77-95.19, P = 0.01) and 8.54 (95% CI 1.14-64.79, P = 0.04), respectively. There was no association between neuropsychiatric adverse events and oseltamivir prescription (P = 0.17).

CONCLUSIONS

Influenza-associated neurologic complications are not uncommon, and most patients fully recovered. The frequency of influenza-associated neurologic complications in Korean children was not significantly different from that of children in Western countries.

Prevalence, Risk Factors, and Outcomes of Influenza-Associated Neurologic Complications in Children

OBJECTIVE

To determine the frequency of neurologic complications associated with influenza in hospitalized children.

STUD DESIGN

We performed a cross-sectional study of children (2 months through 17 years of age) with influenza discharged from 49 children's hospitals in the Pediatric Health Information System during the influenza seasons of 2015-2020. Neurologic complications were defined as encephalopathy, encephalitis, aseptic meningitis, febrile seizure, nonfebrile seizure, brain abscess and bacterial meningitis, Reye syndrome, and cerebral infarction. We assessed length of stay (LOS), intensive care unit (ICU) admission, ICU LOS, 30-day hospital readmissions, deaths, and hospital costs associated with these events. Patient-level risk factors associated with neurologic complications were identified using multivariable logistic regression.

RESULTS

Of 29 676 children hospitalized with influenza, 2246 (7.6%) had a concurrent diagnosis of a neurologic complication; the most frequent were febrile seizures (5.0%), encephalopathy (1.7%), and nonfebrile seizures (1.2%). Hospital LOS, ICU admission, ICU LOS, deaths, and hospital costs were greater in children with neurologic complications compared with those without complications. Risk factors associated with neurologic complications included male sex (aOR 1.1, 95% CI 1.02-1.21), Asian race/ethnicity (aOR 1.7, 95% CI 1.4-2.1) (compared with non-Hispanic White), and the presence of a chronic neurologic condition (aOR 3.7, 95% CI 3.1-4.2).

CONCLUSIONS

Neurologic complications are common in children hospitalized with influenza, especially among those with chronic neurologic conditions, and are associated with worse outcomes compared with children without neurologic complications. These findings emphasize the strategic importance of influenza immunization and treatment, especially in high-risk populations.

Mortality and Neurologic Sequelae in Influenza-Associated Encephalopathy: Retrospective Multicenter PICU Cohort in France

OBJECTIVES

To describe and estimate the mortality rate of severe influenza-associated encephalopathy/encephalitis among children admitted to PICUs.

DESIGN

Multicenter retrospective study.

SETTING

Twelve French PICUs.

PATIENTS

All children admitted for influenza-associated encephalopathy/encephalitis between 2010 and 2018 with no severe preexisting chronic neurologic disorders and no coinfection potentially responsible for the disease.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

We collected the clinical presentation; laboratory, electroencephalographic, and MRI findings; and treatments used in the PICU. The primary outcome was mortality. The secondary outcomes included sequelae at discharge and last follow-up. We included 41 patients with a median (interquartile range) age of 4.7 years (2.5-8.2 yr). The main reasons for admission were altered consciousness (59%) and status epilepticus (34%); 48% of patients had meningitis, and one third had acute necrotizing encephalopathy on MRI. Mechanical ventilation was required in 73% of patients and hemodynamic support in 24%. The use of specific treatments was variable; steroids were given to 49% of patients. Seven patients (17%) died in the PICU. Median (interquartile range) PICU stay length was 7 days (2-13 d), and total hospital length of stay was 23 days (7-33 d). On hospital discharge, 49% (n = 20) had neurologic sequelae, with 27% (n = 11) having severe disabilities defined by modified Rankin Score greater than or equal to 4.

CONCLUSIONS

Children requiring PICU admission for influenza-associated encephalopathy/encephalitis have high mortality and morbidity rates. The management remains highly variable due to the lack of guidelines.

Continuous Blood purification on Influenza-Associated Neurological Disease in children: a retrospective cohort study

Background

Due to lack of proven therapies, we evaluated the effect of CBP on Influenza-Associated Neurological Disease in children.

Methods

A single-center, retrospective, cohort study was conducted in Luoyang, Henan province, China from January 2018 to January 2020. Children (<18 years) with influenza-associated neurological disease were enrolled in the study. Children with indications for CBP and parental consent received CBP (Continuous Blood purification), while others received maximal intensive care treatment because of the absence of parental consent. The outcomes of the CBP and non-CBP groups were compared. Categorical variables were presented as percentage and compared by Chi-square test. Continuous variables were expressed as median (interquartile ranges) and compared with non-parametric independent sample test. Statistical analyses were carried out by SPSS (version 26.0) and p < 0.05 (2 tailed) was considered to be statistically significant.

Results

30 children with influenza-associated neurological disease were recruited to the study. 18 received CBP and the other 12 received maximal intensive care. There were no differences between CBP and non-CBP children in age, sex, body weight, type of influenza virus, neurological complications, Glasgow score, PIM-2 score and PCIS at admission (p > 0.05). The inflammatory factors (CRP, PCT and IL-6) of 30 cases were tested at admission and after 3 days of admission. In the CBP group, there was a significant decrease in IL-6 levels at 3 days of admission (p = 0.003) and a decrease in CRP and PCT levels, but no significant difference (p > 0.05). In the non-CBP group, there were no significant difference on levels of CRP, PCT and IL-6 at admission and 3-day of admission (p > 0.05). The 28-day mortality was significantly lower in the CBP group compared with the non-CBP group (11.11% vs. 50%, p = 0.034).

Conclusions

CBP definitely reduces IL-6 levels significantly. We did find that the survival rate of patients in the CBP group was improved. But we don’t know if there is a relationship between the reduction of IL-6 levels and the survival rate. Trial registration: http://www.chictr.org.cn/index.aspx(ChiCTR2000031754).

Prognostic Factors Among Children With Acute Encephalitis/Encephalopathy Associated With Viral and Other Pathogens

BACKGROUND

Acute encephalitis/encephalopathy (AE) associated with viral and other pathogens leads to neurological sequelae and mortality. Knowing the prognostic factors is therefore important for immediate interventions. We examined early-phase unfavorable prognostic factors among children with AE using a nationwide database.

METHODS

We performed a retrospective cohort study using the Diagnosis Procedure Combination database, which includes approximately half of acute-care inpatients across Japan. We enrolled children aged ≤ 18 years who were hospitalized for AE and discharged from April 2010 to March 2018. The composite unfavorable outcome included the following at discharge: in-hospital death, tracheostomy, enteral tube feeding, and physical rehabilitation. Unfavorable prognostic factors were assessed using a multivariable Poisson regression model including patient characteristics, associated pathogens, and interventions within 2 days of admission adjusting for within-hospital clustering.

RESULTS

This study included 9386 children with AE (median age, 3 years). A total of 241 (2.6%) in-hospital deaths occurred, and 2027 (21.6%) patients had the composite unfavorable outcome. Significant unfavorable prognostic factors were age 12-18 years, congenital anomalies, epilepsy, and Japan Coma Scale score of 100-300 at admission (ie, worse levels of consciousness). In contrast, herpes simplex virus infection and influenza virus infection were associated with favorable outcomes.

CONCLUSIONS

We identified early-phase (within 2 days of admission) unfavorable prognostic factors among children with AE. These findings will help identify patients who may benefit from early aggressive therapeutic interventions.

Protection against neonatal respiratory viral infection via maternal treatment during pregnancy with the benign immune training agent OM-85

Objectives

Incomplete maturation of immune regulatory functions at birth is antecedent to the heightened risk for severe respiratory infections during infancy. Our forerunner animal model studies demonstrated that maternal treatment with the microbial‐derived immune training agent OM‐85 during pregnancy promotes accelerated postnatal maturation of mechanisms that regulate inflammatory processes in the offspring airways. Here, we aimed to provide proof of concept for a novel solution to reduce the burden and potential long‐term sequelae of severe early‐life respiratory viral infection through maternal oral treatment during pregnancy with OM‐85, already in widespread human clinical use.

Methods

In this study, we performed flow cytometry and targeted gene expression (RT‐qPCR) analysis on lungs from neonatal offspring whose mothers received oral OM‐85 treatment during pregnancy. We next determined whether neonatal offspring from OM‐85 treated mothers demonstrate enhanced protection against lethal lower respiratory infection with mouse‐adapted rhinovirus (vMC₀), and associated lung immune changes.

Results

Offspring from mothers treated with OM‐85 during pregnancy display accelerated postnatal seeding of lung myeloid populations demonstrating upregulation of function‐associated markers. Offspring from OM‐85 mothers additionally exhibit enhanced expression of TLR4/7 and the IL‐1β/NLRP3 inflammasome complex within the lung. These treatment effects were associated with enhanced capacity to clear an otherwise lethal respiratory viral infection during the neonatal period, with concomitant regulation of viral‐induced IFN response intensity.

Conclusion

These results demonstrate that maternal OM‐85 treatment protects offspring against lethal neonatal respiratory viral infection by accelerating development of innate immune mechanisms crucial for maintenance of local immune homeostasis in the face of pathogen challenge.

Clinical features and risk factors for severe influenza in children: A study from multiple hospitals in Shanghai

BACKGROUND

The incidence and mortality of influenza in children had risen, but data are limited on children with severe influenza virus infection in China.

METHODS

We conducted a retrospective case-control study and collected the patients' clinical data. Clinical data including demography, clinical presentation, laboratory findings, radiologic findings, treatment and outcomes were collected. Children were clinically confirmed to have virus infection in Shanghai in three hospitals from June 2014 to June 2019.

RESULTS

During the study, 36,047 children were enrolled. Among them, 118 met the criteria for severe flu. Clinical symptoms such as fever, cough, gastrointestinal symptoms, coma and epilepsy were higher in the severe group. Complications such as pneumorrhagia, heart failure, septic shock, acute renal failure and influenza-associated encephalitis were higher in the severe influenza group than the death group. The laboratory findings including decreased hemoglobin, high alanine aminotransferase, high urea nitrogen and high lactate levels were risk factors for death in children with influenza.

CONCLUSION

Influenza-associated encephalopathy (IAE), acute respiratory distress syndrome (ARDS) were the common clinical manifestations and complications for the severe influenza, and delayed use of oseltamivir was found to be associated with fatality.

[A clinical study of influenza A virus infection with neurological symptoms in children]

OBJECTIVE

To study the clinical features of children with influenza A virus infection and neurological symptoms.

METHODS

A retrospective analysis was performed for the clinical data of children with laboratory-confirmed influenza A and neurological symptoms who were treated in Xi'an Children's Hospital Affiliated to Xi'an Jiaotong University from January to December, 2019.

RESULTS

A total of 895 children were diagnosed with influenza A, among whom 291 had neurological symptoms. Boys had a significantly higher incidence rate of influenza A than girls (P < 0.05), and the children aged 1-3 years had a significantly higher incidence rate than the other age groups (P < 0.05). Common neurological symptoms included seizures (97.3%), vomiting (24.1%), and headache (7.2%). Febrile seizures were the most common type of seizures, accounting for 88%. There was no significant difference in the time from disease onset to seizures and frequency seizures between the children with a history of febrile seizures and those without such history (P > 0.05). Of all the children, 3 were diagnosed with acute necrotizing encephalopathy (ANE), all of whom were girls and suffered seizures; the time from the first seizures to the occurrence of disturbance of consciousness was 0-7 hours, and 2 girls died within 2 days after disease onset. All children, except 2 who died of ANE and 1 with neurological sequelae, were cured.

CONCLUSIONS

There is a high incidence rate of neurological symptoms in children with influenza A, and seizures are the most common symptom. Most of the patients with neurological symptoms tend to have a good prognosis, but those with ANE may have a poor prognosis.

Comparison of severe pediatric complicated influenza patients with and without neurological involvement

ABSTRACT

Although influenza is generally an acute, self-limited, and uncomplicated disease in healthy children, it can result in severe morbidity and mortality. The objectives of this study were to analyze and compare the clinical features and outcome of severe pediatric influenza with and without central nervous system (CNS) involvement.We conducted a retrospective observational study of children admitted to the pediatric intensive care unit (PICU) of China Medical University Children's Hospital in Taiwan with a confirmed diagnosis of influenza. The demographic data, clinical and laboratory presentations, therapeutic strategies, and neurodevelopmental outcomes for these patients were analyzed. Furthermore, comparison of patients with and without CNS involvement was conducted.A total of 32 children with severe influenza were admitted during the study periods. Sixteen children were categorized as the non-CNS (nCNS) group and 16 children were categorized as the CNS group. Nine of them had underlying disease. The most common complication in the nCNS group was acute respiratory distress syndrome, (n = 8/16), followed by pneumonia (n = 7/16, 44%). In the CNS group, the most lethal complication was acute necrotizing encephalopathy (n = 3/16) which led to 3 deaths. The overall mortality rate was higher in the CNS group (n = 6) than in the nCNS group (n = 1) (37.5% vs 6.25%, P = .03).The mortality rate of severe complicated influenza was significantly higher with CNS involvement. Children with primary cardiopulmonary abnormalities were at high risk of developing severe complicated influenza, while previously healthy children exhibited risk for influenza-associated encephalitis/encephalopathy.

Epidemiology and burden of illness of seasonal influenza among the elderly in Japan: A systematic literature review and vaccine effectiveness meta-analysis

BACKGROUND

Elderly populations are particularly vulnerable to influenza and often require extensive clinical support. In Japan, nationwide passive surveillance monitors seasonal influenza but does not capture the full disease burden. We synthesized existing evidence on the epidemiology, vaccine effectiveness (VE), and economic burden of seasonal influenza in the elderly population.

METHODS

PubMed, EMBASE, and ICHUSHI were searched for articles on seasonal influenza in Japan, published between 1997 and 2018, in English or Japanese. Grey literature was also assessed. A random-effects meta-analysis characterized VE of influenza vaccines among studies reporting this information.

RESULTS

Of 1,147 identified articles, 143 met inclusion criteria. Reported incidence rates varied considerably depending on study design, season, study setting and, most importantly, case definition. In nursing homes, the maximum reported attack rate was 55.2% and in the 16 articles reporting mortality rates, case fatality rates varied from 0.009% to 14.3%. Most hospitalizations were in people aged >60; healthcare costs were partially mitigated by vaccine administration. Meta-analysis estimated overall VE of 19.1% (95% CI: 2.3% - 33.0%) with a high proportion of heterogeneity (I2 : 89.1%). There was a trend of lower VE in older people (40.1% [-57.3-77.2] in the <65 group; 12.9% [-8.0-29.8] in those 65; P = .21).

CONCLUSIONS

Despite differences between studies that make comparisons challenging, the influenza burden in elderly Japanese is significant. While vaccines are effective, current vaccination programs offer suboptimal protection. Health economic data and cost-effectiveness analyses were limited and represent areas for policy-relevant future research.

Rapid and severe neurologic deterioration due to influenza associated encephalopathy in a healthy child

Rapid neurologic deterioration is rare in healthy school age children, particularly in the absence of trauma or toxic exposure. Hemorrhagic or ischemic stroke, infectious etiologies and metabolic causes must be emergently considered. We present the clinical details of a previously well child with two days of mild viral symptoms who progressed from playful and active to severe neurologic injury over the course of eight hours.

Clinical Spectrum and Burden of Influenza-Associated Neurological Complications in Hospitalised Paediatric Patients

BACKGROUND

Influenza is one of the most common causes of acute respiratory tract infections around the world. Influenza viruses can cause seasonal epidemics. There remains limited information on the impact of both seasonal influenza A and influenza B related hospitalisations from neurological complications in paediatric populations in Asia.

OBJECTIVES

To examine both the clinical spectrum and healthcare burden of influenza-associated neurological complications (IANCs) within the paediatric population of Hong Kong.

METHODS

We conducted a population-based retrospective study to identify all paediatric patients (<18 years) admitted to a public hospital in Hong Kong with a confirmed influenza A or B infection between 2014 and 2018 using the Clinical Data Analysis and Reporting System of the Hospital Authority. The clinical spectrum of the paediatric patients with IANCs was studied. The clinical burden of paediatric influenza patients with IANCs were compared to paediatric influenza patients without neurological complications.

RESULTS

A total of 28,016 children admitted to the paediatric wards diagnosed to have influenza A or B infection were identified, accounting for 5.7% (28,016/489,955) of total paediatric admissions. 67.3% had influenza A and 32.7% had influenza B, and 8.9% had IANCs. The mean annual incidence of IANCs in children was 57 per 100,000 population. The spectrum of IANCs in our paediatric patients included febrile seizures (80.6%), myositis (11.4%), seizures with fever (5.4%), influenza-associated encephalitis/encephalopathy (IAE) (2.6%) and rarely Guillain-Barré syndrome (0.04%). Most paediatric patients with IANCs (85.5%) presented at a young age of <6 years. Paediatric patients with IANCs had significant longer hospital stays (p < 0.001), higher percentages of mechanical ventilation use (p < 0.05) and PICU admissions (p < 0.001), and higher mortality rates (p < 0.001) compared to those without neurological complications. Amongst those with IANCs, IAE was the sole cause of all seven reported mortalities.

CONCLUSIONS

Seasonal influenza A & B is a common cause of hospitalisation for paediatric patients in Hong Kong. We found neurological complications from influenza A and B caused a significantly higher clinical burden compared to those without neurological complications. Children in younger age groups (<6 years old) are at highest risk and thus increasing vaccination coverage to this age group is recommended.

Influenza B associated acute necrotising encephalopathy with visual impairment in a child

Influenza-associated encephalopathy/encephalitis (IAE) can result in serious neurological complications. We report a 4-year-old healthy female child with the diagnosis of IAE. Her clinical course was complicated by temporary visual impairment and significant motor deficits. Her unique ophthalmological findings have little precedent in previous literature.

Aphasia and confusion - influenza encephalopathy: atypical presentation of influenza

Influenza encephalopathy, a rare manifestation of influenza infection in the adult population which is not widely recognised, can present with confusion and focal neurological symptoms, including aphasia. The aim of this report is to illustrate the unique presentation of influenza encephalopathy and discuss the need for close attention to and monitoring of this rare but highly fatal disease.A 28-year-old woman was admitted with acute-onset confusion and incoherent speech. CT of the head was unremarkable. Cerebrospinal fluid analysis showed elevation of protein, but was otherwise unremarkable. A detailed history revealed recent upper respiratory symptoms which prompted a rapid influenza test which was positive and oseltamivir was started. The patient's confusion and aphasia gradually improved and her speech was back to her baseline by the next day.

Successful Outcome in an Adult Patient with Influenza-associated Hemorrhagic Shock and Encephalopathy Syndrome

A 50-year-old woman presented with coma and hemorrhagic shock. A rapid influenza antigen test revealed influenza A infection; other laboratory examinations ruled out any other suspected infections. She was diagnosed with hemorrhagic shock and encephalopathy syndrome (HSES) induced by influenza A. She was administered methylprednisolone pulse therapy and peramivir. Subsequently, she was discharged without any sequelae. Only a few cases of influenza-induced HSES have been reported, and the clinical outcomes were very poor. We herein report a successfully treated adult case of influenza-induced HSES and review this rare syndrome.

Early steroid pulse therapy among children with influenza virus-associated encephalopathy

Background

Influenza virus-associated encephalopathy (IAE) can lead to neurological sequela and mortality among children. Therefore, instant recognition and therapeutic intervention for IAE are crucial. In some clinical subtypes of IAE, steroid pulse therapy might be beneficial, especially when it is administered in the early phase. However, early identification of patients who may benefit from steroid pulse therapy is sometimes difficult. We aimed to assess the effectiveness of early steroid pulse therapy among children with IAE.

Methods

In this retrospective observational study, we used a national database that covers half of the acute care inpatients across Japan to identify inpatients aged ≤ 18 years with a diagnosis of IAE between July 2010 and March 2017. Unfavorable outcome was defined as a composite outcome of sequela including Japan Coma Scale ≥ 10 at discharge, requiring tracheostomy, mechanical ventilation, enteral tube feeding, rehabilitation at discharge, or in-hospital death. Propensity score matching was performed to compare unfavorable outcome and in-hospital mortality between patients with and without steroid pulse therapy within 2 days of admission.

Results

Among 692 patients included in the study, the mean age was 5.8 years, and 55.8% were male. The overall in-hospital mortality was 1.3%, and the proportion of the unfavorable outcome was 15.0%. We observed no significant difference in the unfavorable outcome between matched patients (168 patients in each group) with and without early steroid pulse therapy (13.7% vs 8.3%; P = 0.16) or in-hospital mortality (0.6% vs 1.2%; P = 1.0).

Conclusions

We did not observe the effectiveness of early steroid pulse therapy on patient outcomes among children with IAE in our study population including all clinical subtypes of IAE. Further studies considering severity of illness are warranted to determine whether steroid pulse therapy is beneficial, especially for specific clinical subtypes of IAE.

Epidemiological changes of acute encephalopathy in Japan based on national surveillance for 2014-2017

BACKGROUND

We previously reported the nationwide, epidemiological data of acute encephalopathy in Japan during 2007-2010. Here we conducted the second national survey of acute encephalopathy during 2014-2017, and compared the results between the two studies to elucidate the trends in the seven years' interval as well as the influence of changes in pediatric viral infections and guidelines for acute encephalopathy in Japan.

METHODS

The Research Committee on Acute Encephalopathy supported by the Japanese Government sent a questionnaire to 507 hospitals throughout Japan, and collected the responses by mail.

RESULTS

A total of 1115 cases from 267 hospitals reportedly had acute encephalopathy during April 2014-June 2017. In this study, the age at onset was younger, the ratios of recently established syndromes, such as acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) and clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), were higher, and the ratio of influenza-associated encephalopathy was lower, than in the previous study. The age at onset of influenza-associated encephalopathy was lower, and that of HHV-6/7-associated encephalopathy higher, compared to the first survey. The outcomes of entire acute encephalopathy remained unchanged.

CONCLUSION

Some of these changes reflected the recent trends of viral infectious diseases including 2009 influenza pandemic, and others the standardization of the diagnosis of acute encephalopathy in Japan.

Characteristics and outcome of influenza-associated encephalopathy/encephalitis among children in a tertiary pediatric hospital in Italy, 2017-2019

Background

Influenza is the most frequent cause of acute upper respiratory tract infections during winter season. Although rare, neurological manifestations are known to occur during influenza infection and approximatively three-quarters of cases are in children. In this study, we aimed to characterize the burden and clinical spectrum of influenza-associated encephalopathy and encephalitis in children admitted at a tertiary pediatric hospital in Italy over two influenza seasons (2017–2019).

Methods

We retrospectively analyzed clinical, laboratory, instrumental data and outcome of patients discharged with ICD9-CM 487.0 code.

Results

Fifteen children (13.1% of those discharged with a diagnosis of influenza infection in the study period), had influenza-associated central nervous system (CNS) manifestations. Eight patients (53.3%) were diagnosed as influenza encephalitis, 7 (46.7%) as influenza encephalopathy. Median age was 27 months. In children under 2 years of age (40% of all cases) altered consciousness was the most frequent neurological manifestation while respiratory symptoms were present at admission in all cases. Younger children also required intensive care support more frequently. Five subjects (33.3%) presented comorbidity. None of the patients had received seasonal influenza vaccination. The median time from onset of respiratory signs to onset of neurological manifestations was 24 h. Cerebrospinal fluid (CSF) analysis was normal in most patients and polymerase chain reaction for influenza virus RNA on CSF, when performed, was negative in all samples. Neuroradiological investigations, performed in 5 children, reported cortical and subcortical white matter signal alterations. Oseltamivir was administered only in 2 cases. Fourteen patients recovered without sequelae, and only a 2-year-old girl had minimal impairment in fine motor skills at discharge.

Conclusions

All children presenting acute neurological features during influenza season should be evaluated for influenza-associated CNS complications even if the respiratory involvement is mild. Absence of underlying diseases or other risk factors are not protective factors against CNS influenza-associated complications. The lack of CSF pleocytosis does not exclude CNS involvement. Children under 2 years of age are at higher risk of requiring intensive care support.

Influenza virus-related critical illness: pathophysiology and epidemiology

Influenza virus affects the respiratory tract by direct viral infection or by damage from the immune system response. In humans, the respiratory epithelium is the only site where the hemagglutinin (HA) molecule is effectively cleaved, generating infectious virus particles. Virus transmission occurs through a susceptible individual's contact with aerosols or respiratory fomites from an infected individual. The inability of the lung to perform its primary function of gas exchange can result from multiple mechanisms, including obstruction of the airways, loss of alveolar structure, loss of lung epithelial integrity from direct epithelial cell killing, and degradation of the critical extracellular matrix.Approximately 30-40% of hospitalized patients with laboratory-confirmed influenza are diagnosed with acute pneumonia. These patients who develop pneumonia are more likely to be < 5 years old, > 65 years old, Caucasian, and nursing home residents; have chronic lung or heart disease and history of smoking, and are immunocompromised.Influenza can primarily cause severe pneumonia, but it can also present in conjunction with or be followed by a secondary bacterial infection, most commonly by Staphylococcus aureus and Streptococcus pneumoniae. Influenza is associated with a high predisposition to bacterial sepsis and ARDS. Viral infections presenting concurrently with bacterial pneumonia are now known to occur with a frequency of 30-50% in both adult and pediatric populations. The H3N2 subtype has been associated with unprecedented high levels of intensive care unit (ICU) admission.Influenza A is the predominant viral etiology of acute respiratory distress syndrome (ARDS) in adults. Risk factors independently associated with ARDS are age between 36 and 55 years old, pregnancy, and obesity, while protective factors are female sex, influenza vaccination, and infections with Influenza A (H3N2) or Influenza B viruses.In the ICU, particularly during the winter season, influenza should be suspected not only in patients with typical symptoms and epidemiology, but also in patients with severe pneumonia, ARDS, sepsis with or without bacterial co-infection, as well as in patients with encephalitis, myocarditis, and rhabdomyolysis.

Nationwide survey of influenza-associated acute encephalopathy in Japanese adults

BACKGROUND

Knowledge of adult patients with influenza-associated acute encephalopathy (IAE) is limited. We conducted a detailed survey to investigate the prevalence, clinical features, associated outcomes, and prognostic factors in adult IAE patients.

METHOD

A nationwide questionnaire on IAE patients was sent to the departments of Internal Medicine, Neurology, Neurosurgery, and Emergency and Critical Care at all hospitals with ≥200 beds in Japan.

RESULTS

118 patients were diagnosed with IAE during the 2013/14 to 2015/16 influenza seasons, and the estimated annual incidence of IAE in Japanese adults was 0.98/1000,000 population. 44 patients were subsequently enrolled in the detailed study. 93% of patients exhibited disturbance of consciousness. Convulsions and delirious behavior were present in 26% and 40% of patients, respectively. 65% of patients received pulse corticosteroid therapy with methylprednisolone and 21% of patients received intravenous gamma-globulin therapy. 63% of patients achieved a good recovery, but 7% died. Multiple logistic regression analysis revealed that plasma glucose level demonstrated a statistically significant association with poor outcome.

CONCLUSION

This nationwide survey provided data for the annual incidence and clinical features of IAE in Japanese adults. Hyperglycemia was indicated as an independent predictor of poor prognosis in IAE patients and reflected systemic hypercytokinemia in IAE pathogenesis.

Influenza B-related meningoencephalitis in adults

We present a case involving an 85-year-old man with acute confusion and new onset seizure following a 1-week history of respiratory prodrome. This case report describes a case of influenza B-related meningoencephalitis supported by evidence of an influenza B infection and temporal relation of the neurological event and respiratory illness in the absence of other identifiable cause. Diagnosis is guided by cerebrospinal fluid profile and nasopharyngeal PCR. Treatment is largely supportive and the effect of vaccination on prevention of this neurological complication remains unclear.