Influenza-Associated Neurological Complications

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.

A case report and literature review on tocilizumab-cured acute necrotizing encephalopathy caused by influenza A virus

Introduction

Acute Necrotizing Encephalopathy (ANE), is a kind of severe Central Nervous System Disease. The commonest pathogen is the influenza virus. The pathogenesis of ANE is bound up to genetic susceptibility and cytokine storm. Interleukin-6 (IL-6) is deemed as the core function in cytokine storm of ANE and that plays a significant role in evaluating the severity of Influenza-Related ANE. Tocilizumab, an IL-6 antagonist, is known to be safe and effective in the treatment of ANE when used early and has an essential role in improving prognosis and preventing disability.

Case report

This case reports a 2 year 10 month old boy who developed ANE after being infected with influenza A virus (H1N1-2019). After treatment with Tocilizumab, the child's consciousness was clear, no convulsions occurred, the movement of limbs was improved, and the lesions of encephalopathy were significantly reduced.

Conclusion

The early use of Tocilizumab is safe and effective for the treatment of ANE caused by influenza virus.

A Characterization of Neurology Consults for Inpatients with SARS-CoV-2 Infection Compared to Other Respiratory Viruses

Introduction: Neurological consultation for patients infected with SARS-CoV-2 is common; it is currently unknown whether the neurologist's approach to inpatient consultation of patients with SARS-CoV-2 should differ from the paradigm used to evaluate hospitalized patients with similar respiratory viruses. The goal of the present study is to determine if the preponderance of new neurologic diagnoses differs between inpatients with SARS-CoV-2 and similar non-SARS-CoV-2 respiratory viruses for whom neurology is consulted. Methods: We performed a retrospective chart analysis of inpatient neurologic consultations at three major Philadelphia-based hospitals. We compared the final neurologic diagnosis of 152 patients infected with SARS-CoV-2 to 54 patients with a similar ubiquitous non-SARS-CoV-2 respiratory virus (influenza A, influenza B, respiratory syncytial virus, rhinovirus, or adenovirus, the most commonly tested respiratory viruses at our institution). Secondary metrics included age, sex, level of care, prior neurologic diagnoses, and mortality. A multinomial logistic regression model was utilized to evaluate the relative difference between diagnostic category groups on all metrics. Results: The proportion of patients with seizure who were infected with SARS-CoV-2 admitted to an intensive care unit (ICU) was significantly higher than those who were admitted to a medical-surgical floor. SARS-CoV-2 was also associated with increased risk for ICU admission compared to other common respiratory viruses. SARS-CoV-2 inpatients requiring neurologic consultation were also more likely to be older and female as compared to the non-SARS-CoV-2 cohort. In other domains, the proportion of neurologic diagnoses between SAR-CoV-2 and non-SARS-CoV-2 respiratory viruses showed no significant difference. Conclusion: Patients requiring inpatient neurologic consultation with a diagnosis of SARS-CoV-2 infection or another respiratory virus were found to be remarkably similar in terms of their ultimate neurologic diagnosis, with the exception of a larger preponderance of seizure in critical-care-level patients with SARS-CoV-2 infection. Our study suggests that the neurological approach to patients hospitalized with SARS-CoV-2 should be similar to that for patients with similar common respiratory infections, noting that seizure was seen more frequently in critically ill patients infected with SARS-CoV-2.

Antiviral Approaches against Influenza Virus

Preventing and controlling influenza virus infection remains a global public health challenge, as it causes seasonal epidemics to unexpected pandemics. These infections are responsible for high morbidity, mortality, and substantial economic impact. Vaccines are the prophylaxis mainstay in the fight against influenza. However, vaccination fails to confer complete protection due to inadequate vaccination coverages, vaccine shortages, and mismatches with circulating strains. Antivirals represent an important prophylactic and therapeutic measure to reduce influenza-associated morbidity and mortality, particularly in high-risk populations. Here, we review current FDA-approved influenza antivirals with their mechanisms of action, and different viral- and host-directed influenza antiviral approaches, including immunomodulatory interventions in clinical development. Furthermore, we also illustrate the potential utility of machine learning in developing next-generation antivirals against influenza.

Neurologic Manifestations of Influenza in Children

OBJECTIVE

We assessed the neurologic manifestation of influenza among hospitalized children with influenza (neuro-flu), comparing their demographic and clinical characteristics to hospitalized children without neurologic manifestation (classic-flu).

METHODS

A retrospective, cohort study. All children with laboratory confirmed influenza (PCR), admitted to the Soroka University Medical Center (SUMC) between 2016 and 2019 were included.

RESULTS

Overall, 951 patients were identified: 201 with neuro-flu, and 750 with classic-flu. Seizures (n = 125) were the most common neurological manifestation of neuro-flu (seizure-flu): 73 simple febrile seizures, 45 atypical febrile seizures, and 7 afebrile seizures. Neurological comorbidities rates were significantly higher in neuro-flu versus classic-flu (13.0% vs. 6.0%), while respiratory and cardiac comorbidities were less common in neuro-flu (4.5% and 0.5% vs. 8.0% and 4.5%, respectively). Neuro-flu (compared with classic-flu) was associated with leukocytosis (21.0% vs. 13.0%, P < 0.001) and lower C-reactive protein (CRP) levels (2.4 ± 4.1 vs. 3.3 ± 5.4, P = 0.03). Notably, patients with classic flu had a more prominent respiratory disease, as they had more chest radiographs (CXR) performed (60.5% vs. 45.0%, P < 0.001), higher rates of pneumonia (27.0% vs. 12.0%, P < 0.001), and antibiotic (antibacterial) treatment (60.0% vs. 42.0%, P < 0.001).

CONCLUSIONS

Influenza can appear as a neurologic disease, manifested mainly with febrile seizures. Children with neuro-flu have more neurologic comorbidities, suggesting that neuro-flu is mainly driven by host-factors, rather than by pathogen-factors. The relatively lower rates of pneumonia in neuro-flu suggests that these patients are admitted in the early stage of the influenza infection, which triggers the neurologic response.

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.

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.

SARS-CoV-2 infection increases the gene expression profile for Alzheimer's disease risk

The coronavirus disease 2019 (COVID-19) pandemic has caused over 600,000,000 infections globally thus far. Up to 30% of individuals with mild to severe disease develop long COVID, exhibiting diverse neurologic symptoms including dementias. However, there is a paucity of knowledge of molecular brain markers and whether these can precipitate the onset of Alzheimer's disease (AD). Herein, we report the brain gene expression profiles of severe COVID-19 patients showing increased expression of innate immune response genes and genes implicated in AD pathogenesis. The use of a mouse-adapted strain of SARS-CoV-2 (MA10) in an aged mouse model shows evidence of viral neurotropism, prolonged viral infection, increased expression of tau aggregator FKBP51, interferon-inducible gene Ifi204, and complement genes C4 and C5AR1. Brain histopathology shows AD signatures including increased tau-phosphorylation, tau-oligomerization, and α-synuclein expression in aged MA10 infected mice. The results of gene expression profiling of SARS-CoV-2-infected and AD brains and studies in the MA10 aged mouse model taken together, for the first time provide evidence suggesting that SARS-CoV-2 infection alters expression of genes in the brain associated with the development of AD. Future studies of common molecular markers in SARS-CoV-2 infection and AD could be useful for developing novel therapies targeting AD.

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.

Therapeutic and palliative role of a Unani herbal decoction in COVID-19 and similar respiratory viral illnesses: Phytochemical & pharmacological perspective

ETHNOPHARMACOLOGICAL RELEVANCE

Outbreaks of respiratory viral infections like Severe Acute Respiratory Syndrome, Middle-East Respiratory Syndrome, and Coronavirus Disease-2019 have been a regular occurrence in the past 100 years. A significant proportion of the morbidity and mortality in influenza is attributed to the co-morbidities and complications induced by the disease, involving the vital organs and physiological functions. In this context, traditional medicines offer effective protective, palliative, and therapeutic benefits, as observed in several studies on various types of influenza, including COVID-19. The Unani herbal decoction comprising of 'Unnāb (Ziziphus jujuba Mill. fruit), Sapistān (Cordia dichotoma G. Forst. fruit), and Behīdāna (Cydonia oblonga Mill. seed) was originally prescribed by Hakim Ajmal Khan (1868-1927 AD) for various respiratory ailments as a bronchodilator, anti-inflammatory, and for clearing the respiratory tract. During COVID-19, the decoction was prescribed by the Ministry of Ayurveda, Yoga, Unani, Siddha, and Homeopathy (AYUSH), Government of India, for mild patients in home isolation, and also as a self-care drink for healthy people. Preliminary studies are of the view that the decoction could reduce COVID-19 incidence and prevent severe disease in the population where it was administered.

AIMS OF THE STUDY

We intend to review the pharmacological activity of the Unani decoction ingredients, i.e., Z. jujuba, C. dichotoma, and C. oblonga, in context with respiratory viral infections and their co-morbidities, to develop an understanding of its action mechanism.

METHODOLOGY

We reviewed Unani classical textbooks for information on the therapeutic activity of the decoction ingredients. Scientific studies published in English from the year 2000 onwards on leading scientific websites (PubMed, MEDLINE, Scopus, and Springer) were searched for information regarding the efficacy of the drugs in influenza and its common complications. Non-English language articles, or those published prior to 2000, and those which included plant parts other than those traditionally included in the decoction were excluded.

OBSERVATIONS

A wide range of therapeutic and palliative effects have been observed in the three herbs included in the Unani decoction, including anti-viral, anti-bacterial, immuno-modulatory, anti-inflammatory, hepato-, and nephroprotective, anti-atherosclerotic, anti-tussive, broncho-dilatory, and regulation of gut microbiota. Together, these effects can help to mitigate and prevent most of the complications caused as a result of respiratory viral infections.

CONCLUSION

The combined effects of ingredients in this Unani herbal decoction can potentially help to mitigate most of the pathological changes and complications caused by influenza viruses. With further clinical research, the decoction may be potentially utilized as a prophylactic and therapeutic against viral influenza.

Influenza A, Influenza B, and SARS-CoV-2 Similarities and Differences – A Focus on Diagnosis

In late December 2019, the first cases of viral pneumonia caused by an unidentified pathogen were reported in China. Two years later, SARS-CoV-2 was responsible for almost 450 million cases, claiming more than 6 million lives. The COVID-19 pandemic strained the limits of healthcare systems all across the world. Identifying viral RNA through real-time reverse transcription-polymerase chain reaction remains the gold standard in diagnosing SARS-CoV-2 infection. However, equipment cost, availability, and the need for trained personnel limited testing capacity. Through an unprecedented research effort, new diagnostic techniques such as rapid diagnostic testing, isothermal amplification techniques, and next-generation sequencing were developed, enabling accurate and accessible diagnosis. Influenza viruses are responsible for seasonal outbreaks infecting up to a quarter of the human population worldwide. Influenza and SARS-CoV-2 present with flu-like symptoms, making the differential diagnosis challenging solely on clinical presentation. Healthcare systems are likely to be faced with overlapping SARS-CoV-2 and Influenza outbreaks. This review aims to present the similarities and differences of both infections while focusing on the diagnosis. We discuss the clinical presentation of Influenza and SARS-CoV-2 and techniques available for diagnosis. Furthermore, we summarize available data regarding the multiplex diagnostic assay of both viral infections.

Neurological outcomes one year after COVID-19 diagnosis: a prospective longitudinal cohort study

INTRODUCTION

Neurological sequelae from COVID-19 may persist after recovery from acute infection. Here, we aimed to describe the natural history of neurological manifestations over one year after COVID-19.

METHODS

We performed a prospective, multicentre, longitudinal cohort study in COVID-19 survivors. At 3-month and 1-year follow-up, patients were assessed for neurological impairments by a neurological examination and a standardized test battery including the assessment of hyposmia (16-item Sniffin-Sticks-test, SS-16), cognitive deficits (Montreal Cognitive Assessment<26), and mental health (Hospital Anxiety and Depression Scale, and Post-traumatic Stress Disorder Checklist-5).

RESULTS

Eighty-one patients were evaluated one year after COVID-19, out of which 76/81 (94%) patients completed 3-month and 1-year follow-up. Patients were 54 (47-64) years old and 59% were male. New and persistent neurological disorders were found in 15% (3-months) and 12% (10/81; 1-year). Symptoms at 1-year follow-up were reported by 48/81 (59%) patients, including fatigue (38%), concentration difficulties (25%), forgetfulness (25%), sleep disturbances (22%), myalgia (17%), limb weakness (17%), headache (16%), impaired sensation (16%), and hyposmia (15%). Neurological examination revealed findings in 52/81 (64%) patients without improvement over time (3-months: 61%, p=0.230) including hyposmia (SS-16<13; 51%). Cognitive deficits were apparent in 18%, whereas depression, anxiety, and post-traumatic stress disorders were diagnosed in 6%, 29%, and 10% one year after infection, respectively. These mental and cognitive disorders did not improve since 3-month follow-up (all p>0.05).

CONCLUSION

Our data indicate that a significant patient number still suffer from neurological sequelae including neuropsychiatric symptoms one year after COVID-19 calling for interdisciplinary management of these patients.

Effects of Antiviral Therapy and Glucocorticoid Therapy on Fever Duration in Pediatric Patients with Influenza

Background and Objectives: Considering developing resistance against neuraminidase inhibitors (NAIs) and their adverse reactions, restricted use of NAIs and use of alternative drugs should be considered for treating influenza. Although glucocorticoids (GCs) have been used for severe influenza, their effects on non-severe influenza have rarely been evaluated. This study aimed to evaluate the clinical responses to NAI therapy and GC therapy in pediatric patients with non-severe influenza. Materials and Methods: A total of 601 pediatric patients (<19 years of age) diagnosed with non-severe influenza were retrospectively recruited to evaluate the effects of NAI therapy and GC therapy. Post-admission fever duration and hospitalization duration were compared among four patient groups divided by the administered treatment: No therapy (n = 52), NAI therapy (n = 154), GC therapy (n = 123), and Both therapies (n = 272). Results: In a multivariate analysis with adjustment for confounding variables, the post-admission fever duration was not significantly different among the four patient groups. The post-admission fever duration tended to shorten with increasing age, longer pre-admission fever duration, and incidence of influenza A virus infection and lower respiratory tract infection. The type of administered treatment showed no significant effects on the post-admission fever duration in any subgroups according to patient age, pre-admission fever duration, influenza virus subtype, and clinical diagnosis. Conclusions: Symptomatic treatment rather than antiviral or GC therapy seems to be sufficient for patients with non-severe influenza, although the effects of NAI therapy and GC therapy according to their administered time and dose should be further evaluated.

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).

Neurologic Manifestations of the World Health Organization's List of Pandemic and Epidemic Diseases

The World Health Organization (WHO) monitors the spread of diseases globally and maintains a list of diseases with epidemic or pandemic potential. Currently listed diseases include Chikungunya, cholera, Crimean-Congo hemorrhagic fever, Ebola virus disease, Hendra virus infection, influenza, Lassa fever, Marburg virus disease, Neisseria meningitis, MERS-CoV, monkeypox, Nipah virus infection, novel coronavirus (COVID-19), plague, Rift Valley fever, SARS, smallpox, tularemia, yellow fever, and Zika virus disease. The associated pathogens are increasingly important on the global stage. The majority of these diseases have neurological manifestations. Those with less frequent neurological manifestations may also have important consequences. This is highlighted now in particular through the ongoing COVID-19 pandemic and reinforces that pathogens with the potential to spread rapidly and widely, in spite of concerted global efforts, may affect the nervous system. We searched the scientific literature, dating from 1934 to August 2020, to compile data on the cause, epidemiology, clinical presentation, neuroimaging features, and treatment of each of the diseases of epidemic or pandemic potential as viewed through a neurologist's lens. We included articles with an abstract or full text in English in this topical and scoping review. Diseases with epidemic and pandemic potential can be spread directly from human to human, animal to human, via mosquitoes or other insects, or via environmental contamination. Manifestations include central neurologic conditions (meningitis, encephalitis, intraparenchymal hemorrhage, seizures), peripheral and cranial nerve syndromes (sensory neuropathy, sensorineural hearing loss, ophthalmoplegia), post-infectious syndromes (acute inflammatory polyneuropathy), and congenital syndromes (fetal microcephaly), among others. Some diseases have not been well-characterized from a neurological standpoint, but all have at least scattered case reports of neurological features. Some of the diseases have curative treatments available while in other cases, supportive care remains the only management option. Regardless of the pathogen, prompt, and aggressive measures to control the spread of these agents are the most important factors in lowering the overall morbidity and mortality they can cause.

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.

Acute amnestic syndrome with hippocampal lesion due to influenza B-associated encephalopathy

Acute encephalopathy is a rare complication of influenza, particularly in adults. We report the case of a 77-year-old woman presenting with complete anterograde and significant retrograde amnesia developing during an influenza B infection. Cranial magnetic resonance imaging (MRI) showed hippocampal lesions including restricted diffusion during the acute phase. Symptoms partially improved following treatment with intravenous methylprednisolone and immunoglobulins but an amnesic syndrome persisted. We discuss possible causes of neurological complications in influenza infections.

Respiratory and Nonrespiratory Diagnoses Associated With Influenza in Hospitalized Adults

IMPORTANCE

Seasonal influenza virus infection is a major cause of morbidity and mortality and may be associated with respiratory and nonrespiratory diagnoses.

OBJECTIVE

To examine the respiratory and nonrespiratory diagnoses reported for adults hospitalized with laboratory-confirmed influenza between 2010 and 2018 in the United States.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the US Influenza Hospitalization Surveillance Network (FluSurv-NET) from October 1 through April 30 of the 2010-2011 through 2017-2018 influenza seasons. FluSurv-NET is a population-based, multicenter surveillance network with a catchment area that represents approximately 9% of the US population. Patients are identified by practitioner-ordered influenza testing. Adults (aged ≥18 years) hospitalized with laboratory-confirmed influenza were included in the study.

EXPOSURES

FluSurv-NET defines laboratory-confirmed influenza as a positive influenza test result by rapid antigen assay, reverse transcription-polymerase chain reaction, direct or indirect fluorescent staining, or viral culture.

MAIN OUTCOMES AND MEASURES

Acute respiratory or nonrespiratory diagnoses were defined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) discharge diagnosis codes. The analysis included calculation of the frequency of acute respiratory and nonrespiratory diagnoses with a descriptive analysis of patient demographic characteristics, underlying medical conditions, and in-hospital outcomes by respiratory and nonrespiratory diagnoses.

RESULTS

Of 89 999 adult patients hospitalized with laboratory-confirmed influenza, 76 649 (median age, 69 years; interquartile range, 55-82 years; 55% female) had full medical record abstraction and at least 1 ICD code for an acute diagnosis. In this study, 94.9% of patients had a respiratory diagnosis and 46.5% had a nonrespiratory diagnosis, including 5.1% with only nonrespiratory diagnoses. Pneumonia (36.3%), sepsis (23.3%), and acute kidney injury (20.2%) were the most common acute diagnoses. Fewer patients with only nonrespiratory diagnoses received antiviral therapy for influenza compared with those with respiratory diagnoses (81.4% vs 88.9%; P < .001).

CONCLUSIONS AND RELEVANCE

Nonrespiratory diagnoses occurred frequently among adults hospitalized with influenza, further contributing to the burden of infection in the United States. The findings suggest that during the influenza season, practitioners should consider influenza in their differential diagnosis for patients who present to the hospital with less frequently recognized manifestations and initiate early antiviral treatment for patients with suspected or confirmed infection.

Clinical Characteristics and Prognosis of Influenza B Virus-Related Hospitalizations in Northern China during the 2017-18 Influenza Season: A Multicenter Case Series

Background

By weekly monitoring of China's influenza situation, Chinese National Influenza Center observed that the 2017-18 season was predominated by influenza B virus (IBV)/Yamagata. No studies regarding hospitalizations in adults with IBV infections have been performed. We aimed to describe the clinical characteristics of hospitalized patients with IBV infection in northern China.

Methods

In this multicenter and retrospective study, we reviewed all consecutive adult patients with confirmed IBV infections at two level A tertiary teaching hospitals in northern China during the 2017-18 influenza season. Patients' clinical and diagnostic findings, as well as administered treatments and mortality data, were analyzed.

Results

A total of 573 patients with a confirmed diagnosis of IBV infection were identified, of whom 22 cases were analyzed because of IBV-related hospitalization. Most patients were admitted to the intensive care unit (ICU) and had at least one underlying disease. The total in-hospital mortality was 27.3%. An elevated initial pneumonia severity index score, elevated direct bilirubin values, and lower platelet levels were associated with mortality (p=0.020, 0.013, and 0.049, respectively). The quick development of bilateral diffuse alveolar infiltrates was the most common imaging characteristics, following consolidation and pleural effusion(s). Risk factors such as HIV infection, pregnancy, underlying medical conditions, coinfections, and treatment delays were not associated with mortality.

Conclusions

IBV should not be neglected because of its significant mortality. The elderly and patients with comorbidities, such as hypertension, diabetes, and connective tissue diseases, are more likely to have severe IBV-related pneumonia. Higher heart rates, direct bilirubin levels, initial PSI scores, and lower platelet levels are correlated with hospital mortality. Increased uptake in tetravalent influenza vaccine should be very helpful in preventing future cases of IBV hospitalizations.

CSF neopterin, a useful biomarker in children presenting with influenza associated encephalopathy?

PURPOSE

Neurological complications of influenza cause significant disease in children. Central nervous system inflammation, the presumed mechanism of influenza-associated encephalopathy, is difficult to detect. Characteristics of children presenting with severe neurological complications of influenza, and potential biomarkers of influenza-associated encephalopathy are described.

METHODS

A multi-center, retrospective case-series of children with influenza and neurological complications during 2017 was performed. Enrolled cases met criteria for influenza-associated encephalopathy or had status epilepticus. Functional outcome at discharge was compared between groups using the Modified Rankin Scale (mRS).

RESULTS

There were 22 children with influenza studied of whom 11/22 had encephalopathy and 11/22 had status epilepticus. Only one child had a documented influenza immunization. The biomarker CSF neopterin was tested in 10/11 children with encephalopathy and was elevated in 8/10. MRI was performed in all children with encephalopathy and was abnormal in 8 (73%). Treatment of children with encephalopathy was with corticosteroids or intravenous immunoglobulin in 9/11 (82%). In all cases oseltamivir use was low (59%) while admission to the intensive care unit was frequent (14/22, 66%). Clinical outcome at discharge was moderate to severe disability (mRS score > 2) in the majority of children with encephalopathy (7/11, 64%), including one child who died. Children with status epilepticus recovered to near-baseline function in all cases.

CONCLUSION

Raised CSF neopterin was present in most cases of encephalopathy, and along with diffusion restriction on MRI, is a useful diagnostic biomarker. Lack of seasonal influenza vaccination represents a missed opportunity to prevent illness in children, including severe neurological disease.

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.

Influenza-associated Encephalitis/Encephalopathy Identified by the Australian Childhood Encephalitis Study 2013-2015

BACKGROUND

Influenza-associated encephalitis/encephalopathy (IAE) is an important cause of acute encephalitis syndrome in children. IAE includes a series of clinicoradiologic syndromes or acute encephalopathy syndromes that have been infrequently reported outside East Asia. We aimed to describe cases of IAE identified by the Australian Childhood Encephalitis study.

METHODS

Children ≤ 14 years of age with suspected encephalitis were prospectively identified in 5 hospitals in Australia. Demographic, clinical, laboratory, imaging, and outcome at discharge data were reviewed by an expert panel and cases were categorized by using predetermined case definitions. We extracted cases associated with laboratory identification of influenza virus for this analysis; among these cases, specific IAE syndromes were identified where clinical and radiologic features were consistent with descriptions in the published literature.

RESULTS

We identified 13 cases of IAE during 3 southern hemisphere influenza seasons at 5 tertiary children's hospitals in Australia; 8 children with specific acute encephalopathy syndromes including: acute necrotizing encephalopathy, acute encephalopathy with biphasic seizures and late diffusion restriction, mild encephalopathy with reversible splenial lesion, and hemiconvulsion-hemiplegia syndrome. Use of influenza-specific antiviral therapy and prior influenza vaccination were infrequent. In contrast, death or significant neurologic morbidity occurred in 7 of the 13 children (54%).

CONCLUSIONS

The conditions comprising IAE are heterogeneous with varied clinical features, magnetic resonance imaging changes, and outcomes. Overall, outcome of IAE is poor emphasizing the need for optimized prevention, early recognition, and empiric management.

Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging diagnosis

Background: Acute influenza-associated encephalopathy/encephalitis (IAE) in adults is a rare but well-known complication of influenza virus infection. The diagnosis is difficult to make due to the absence of distinctive clinical symptoms and validated diagnostic criteria. We present an illustrative case and a case review on acute IAE in adults. Methods: We performed a Medline search of the English literature using the terms influenz*, encephal* and adult, and constructed a database of detailed descriptions of patients with influenza virus infection with influenza-like symptoms at the onset of neurological symptoms. Results: A total of 44 patients were included. Confusion and seizures were the most prevalent neurological symptoms, present in 12 (27 %) and 10 (23 %) patients, respectively. Magnetic resonance imaging (MRI) was performed in 21 patients and anomalies were found in 13 (62 %), with lesions located throughout the brain. Influenza virus RNA was detected in cerebrospinal fluid (CSF) in 5 (16 %) of 32 patients. Eight (18 %) of the forty-four patients died. The benefits of antiviral and immunomodulatory therapy have not been well studied. Discussion: Our results show that many different neurological symptoms can be present in patients with acute onset IAE. Therefore, the diagnosis should be considered in patients with fever and neurological symptoms, especially during the influenza season. Laboratory diagnosis consists of demonstration of influenza virus RNA in brain tissue, CSF or respiratory samples, and demonstration of intrathecal antibody production against influenza virus. The presence of brain lesions in MRI and influenza virus in CSF appear to be of prognostic value.

New Onset Refractory Status Epilepticus in a Young Man with H1N1 Infection

Objective. To report a case of refractory status epilepticus (SE) as an unusual early manifestation of H1N1 influenza infection. Introduction. H1N1 neurological complications have been reported and consist mainly of seizures or encephalopathy occurring in children. However, we only found a single report of an adult developing complex partial SE with H1N1 infection. Case Report. A 21-year-old previously healthy man was brought to the emergency room (ER) after a witnessed generalized tonic clonic seizure (GTCS). He was fully alert and afebrile upon ER arrival, but a second GTCS prompted treatment with Lorazepam and Fosphenytoin. The initial EEG showed diffuse slowing, but a repeat one requested as the patient failed to regain consciousness revealed recurrent focal seizures of independent bihemispheric origin, fulfilling the criteria for nonconvulsive SE. Chest X-ray, followed by chest CT scan, showed a left upper lobe consolidation. H1N1 infection was confirmed with PCR on bronchoalveolar lavage material. Despite aggressive treatment with Midazolam, Propofol, and multiple high dose antiepileptic drugs, the electrographic seizures recurred at every attempt to reduce the intravenous sedative drugs. The patient died two weeks after his initial presentation. Conclusion. H1N1 should be added to the list of rare causes of refractory SE, regardless of the patient's age.