A new factor influencing pathogen detection by molecular assay in children with both mild and severe hand, foot, and mouth disease

Characterization of viral infections in children with influenza-like-illness during December 2018-January 2019

Introduction

Respiratory viral infection (RVI) is of very concern after the outbreak of COVID-19, especially in pediatric departments. Learning pathogen spectrum of RVI in children previous the epidemic of COVID-19 could provide another perspective for understanding RVI under current situation and help to prepare for the post COVID-19 infection control.

Methods

A nucleic acid sequence-based amplification (NASBA) assay, with 19 pairs of primers targeting various respiratory viruses, was used for multi-pathogen screening of viral infections in children presenting influenza-like illness (ILI) symptoms. Children with ILI at the outpatient department of Beijing Tsinghua Changgung Hospital during the influenza epidemic from 12/2018 to 01/2019 were included. Throat swabs were obtained for both the influenza rapid diagnostic test (IRDT) based on the colloidal gold immunochromatographic assay and the NASBA assay, targeting various respiratory viruses with an integrated chip technology.

Results and discussion

Of 519 patients, 430 (82.9%) were positive in the NASBA assay. The predominant viral pathogens were influenza A H1N1 pdm1/2009 (pH1N1) (48.4%) and influenza A (H3N2) (18.1%), followed by human metapneumovirus (hMPV) (8.8%) and respiratory syncytial virus (RSV) (6.1%). Of the 320 cases identified with influenza A by NASBA, only 128 (40.0%) were positive in the IRDT. The IRDT missed pH1N1 significantly more frequently than A (H3N2) (P<0.01). Influenza A pH1N1 and A (H3N2) were the major pathogens in <6 years and 6-15 years old individuals respectively (P<0.05). In summary, influenza viruses were the major pathogens in children with ILI during the 2018-2019 winter influenza epidemic, while hMPV and RSV were non-negligible. The coexistence of multiple pathogen leading to respiratory infections is the normalcy in winter ILI cases.

Diagnostic performance of different specimens in detecting enterovirus A71 in children with hand, foot and mouth disease

Hand, foot and mouth disease (HFMD) is a major public health problem among children in the Asia-Pacific region. The optimal specimen for HFMD virological diagnosis remains unclear. Enterovirus A71 (EV-A71) neutralizing antibody titres detected in paired sera were considered the reference standard for calculating the sensitivity, specificity, positive and negative predictive value of throat swabs, rectal swabs, stool, blood samples and cerebrospinal fluid (CSF) by RT-PCR or ELISA assay. In this study, clinical samples from 276 HFMD patients were collected for analysing the sensitivity of different kind of specimens. Our results showed that stool had the highest sensitivity (88%, 95% CI: 74%-96%) and agreement with the reference standard (91%). The order of diagnostic yield for EV-A71 infection was stool sample ​≥ ​rectal swab ​> ​throat swab ​> ​blood sample ​> ​CSF sample, and using a combination of clinical samples improved sensitivity for enterovirus detection. The sensitivity of ELISA for IgM antibody detection in sterile-site specimens was significantly higher than that of RT-PCR (serum/plasma: 62% vs. 2%, CSF: 47% vs. 0%) (P ​< ​0.002). In conclusion, our results suggest that stool has the highest diagnostic yield for EV-A71-infected HFMD. If stool is unavailable, rectal swabs can be collected to achieve a similar diagnostic yield. Otherwise, throat swabs may be useful in detecting positive samples. Although IgM in blood or CSF is diagnostically accurate, it lacks sensitivity, missing 40%-50% of cases. The higher proportion of severe cases and shorter interval between onset and sampling contributed to the increase in congruency between clinical testing and the serological reference standard.

Low-frequency, exhausted immune status of CD56dim NK cells and disordered inflammatory cytokine secretion of CD56bright NK cells associated with progression of severe HFMD, especially in EV71-infected patients

BACKGROUND

The roles of CD56^bright and CD56^dim natural killer (NK) subsets in the viral clearance and inflammatory processes of hand, foot, and mouth disease (HFMD) remain undefined.

METHODS

A total of 39 HCs and 55 patients were enrolled to analyze peripheral CD56^bright and CD56^dim NK cells according to cell number, surface receptors, cytotoxic activities, and cytokine production. The plasma concentrations of IL-2, IL-6, IL-10, IFN-γ, TNF-α,and MCP-1 were detected using ELSA.

RESULTS

Peripheral blood NK cells was significantly lower in severe patients than in HCs due to the dramatic loss of CD56^dim NK cells with no changes in the cell count of CD56^bright NK cells. For mild patients, decreased NKp46 expression coincided with enhanced cytolysis (CD107a, GNLY, and GrB) in CD56^dim NK cells and decreased NKG2A expression with enhanced IL-10 production in CD56^bright NK cells. In contrast, severe patients showed the dominant expression of NKG2A and decreased expression of NKG2D accompanied by cytotoxic dysfunction in CD56^dim NK cells. Imbalanced receptor expression coincided with the increased concentrations of TNF-α in CD56^bright NK cells. Moreover, EV71+ patients showed significantly decreased counts of CD56^dim NK cells with cytolysis dysfunction, displayed cytokine hypersecretion in CD56^bright NK cells, while the EV71- patients displayed significantly higher plasma cytokine concentrations. The changes in the immune function of NK subsets and their subpopulations were closely related to clinical inflammatory parameters.

CONCLUSIONS

Low-frequency, exhausted immune status of CD56^dim NK cells and disordered inflammatory cytokine secretion of CD56^bright NK cells were associated with the progression of severe HFMD, especially in EV71-infected patients. This promoted the severity of inflammatory disorders, leading to enhanced disease pathogenesis.

A hSCARB2-transgenic mouse model for Coxsackievirus A16 pathogenesis

Background

Coxsackievirus A16 (CA16) is one of the neurotropic pathogen that has been associated with severe neurological forms of hand, foot, and mouth disease (HFMD), but its pathogenesis is not yet clear. The limited host range of CA16 make the establishment of a suitable animal model that can recapitulate the neurological pathology observed in human HFMD more difficult. Because the human scavenger receptor class B, member 2 (hSCARB2) is a cellular receptor for CA16, we used transgenic mice bearing human SCARB2 and nasally infected them with CA16 to study the pathogenicity of the virus.

Methods

Coxsackievirus A16 was administered by intranasal instillation to groups of hSCARB2 transgenic mice and clinical signs were observed. Sampled at different time-points to document and characterize the mode of viral dissemination, pathological change and immune response of CA16 infection.

Results

Weight loss and virus replication in lung and brain were observed in hSCARB2 mice infected with CA16, indicating that these animals could model the neural infection process. Viral antigens were observed in the alveolar epithelia and brainstem cells. The typical histopathology was interstitial pneumonia with infiltration of significant lymphocytes into the alveolar interstitial in lung and diffuse punctate hemorrhages in the capillaries of the brainstem. In addition, we detected the expression levels of inflammatory cytokines and detected high levels of interleukin IL-1β, IL-6, IL-18, and IFN-γ in nasal mucosa, lungs and brain tissues.

Conclusions

The hSCARB2-transgenic mice can be productively infected with CA16 via respiratory route and exhibited a clear tropism to lung and brain tissues, which can serve as a model to investigate the pathogenesis of CA16 associated respiratory and neurological disease.

Role of Renin-Angiotensin System in Acute Lung Injury Caused by Viral Infection

The renin-angiotensin system (RAS) is the most important regulatory system of electrolyte homeostasis and blood pressure and acts through angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis and angiotensin-converting enzyme 2 (ACE2)/angiotensin (1-7)/MAS receptor axis. RAS dysfunction is related to the occurrence and development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and causes a serious prognosis and even death. ALI/ARDS can be induced by various ways, one of which is viral infections, such as SARS-CoV, SARS-CoV-2, H5N1, H7N9, and EV71. This article reviews the specific mechanism on how RAS dysfunction affects ALI/ARDs caused by viral infections. SARS-CoV and SARS-CoV-2 enter the host cells by binding with ACE2. H5N1 and H7N9 avian influenza viruses reduce the ACE2 level in the body, and EV71 increases Ang II concentration. Treatment with angiotensin-converting enzyme inhibitor and angiotensin AT1 receptor blocker can alleviate ALI/ARDS symptoms. This review provides suggestions for the treatment of lung injury caused by viral infections.

Characterization of inflammatory cytokine profiles in cerebrospinal fluid of hand, foot, and mouth disease children with enterovirus 71-related encephalitis in Hangzhou, Zhejiang, China

Enterovirus 71 (EV71) is an important etiological agent of hand, foot, and mouth disease (HFMD), which can also lead to severe neurological complications (eg, encephalitis) in young children. Although a series of reports on EV71 infection have been published, the pathogenic mechanism of EV71 infection is still not fully understood.We evaluated the cerebrospinal fluid (CSF) levels of the inflammatory cytokines interleukin (IL)-8, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, and IL-12p70 in 88 children with EV71-related encephalitis and 19 children with febrile convulsion (FC) with the use of commercial cytometric bead array kits.The levels of IL-8, IL-1β, IL-6, and IL-10 in CSF were significantly higher in encephalitis group when compared with those observed in FC group, while no significant changes were noted in the levels of TNF-α and IL-12p70. In addition, significant and positive correlations among CSF IL-8, IL-1β, IL-6, and IL-10 were observed in encephalitis group. Furthermore, receiver operator characteristic analysis determined a cut-off value of 10.62 pg/mL for IL-6 to discriminate encephalitis patients from FCs with the sensitivity and specificity of 89.8% and 84.2%, respectively. Moreover, logistic regression analyses revealed that IL-6 was an independent predictor of EV71-related encephalitis (odds ratio = 23.241, P < .001).Our results indicate that 4 inflammatory cytokines (IL-8, IL-1β, IL-6, and IL-10) play important roles in the pathogenesis of EV71 infection. IL-6 may be used for the evaluation of EV71-related encephalitis and as a potential therapy candidate for EV71 infection.

Electrochemical Biosensors for Detection of Foodborne Pathogens

Foodborne safety has become a global public health problem in both developed and developing countries. The rapid and precise monitoring and detection of foodborne pathogens has generated a strong interest by researchers in order to control and prevent human foodborne infections. Traditional methods for the detection of foodborne pathogens are often time-consuming, laborious, expensive, and unable to satisfy the demands of rapid food testing. Owing to the advantages of simplicity, real-time analysis, high sensitivity, miniaturization, rapid detection time, and low cost, electrochemical biosensing technology is more and more widely used in determination of foodborne pathogens. Here, we summarize recent developments in electrochemical biosensing technologies used to detect common foodborne pathogens. Additionally, we discuss research challenges and future prospects for this field of study.

Detection and characterization of type B influenza virus from influenza-like illness cases during the 2017-2018 winter influenza season in Beijing, China

In the winter of 2017-2018, there was significant influenza activity in China, resulting in unprecedented usage of influenza rapid antigen tests (IRAT) and neuraminidase inhibitors (NAIs). The aim of this study was to characterize the most prevalent influenza virus type in a clinical setting with respect to diagnosis and concomitant NAI treatment. From Dec 2017 to Jan 2018, 3257 patients with influenza-like illness (ILI) were screened using IRAT. We summarized and compared the results with the last influenza season. Subtyping of influenza B viruses and identification of NAI drug resistance mutations were carried out by sequencing the HA and NA genes and aligning these with genetic isotypes. The performance of IRAT and RT-PCR was compared. Screening results indicated that influenza B virus was the leading cause of this influenza epidemic, with children being more susceptible to infection than adults. Phylogenetic analysis revealed that the prevailing influenza B virus belonged to the Yamagata lineage and were genetically similar to strains isolated from North America in the same influenza season. Cross-continental spread of influenza/B/Yamagata occurred. NAI resistance mutations were not identified in the 18 samples analyzed. The current antiviral protocol was still effective for influenza B control. RT-PCR positivity was significantly higher than that of IRAT (P = 0.004). IRAT and RT-PCR had a consistency rate of 86.9%, with the consistency rates of the positive and negative cases being 54.3% and 97.3%, respectively. Clinicians should be alert to the possibility of obtaining false negative results when using IRAT, and RT-PCR is recommended to improve the accuracy of pathogen detection.

A Simple Scoring System for Quick, Accurate, and Reliable Early Diagnosis of Hand, Foot, and Mouth Disease

BACKGROUND To construct an accurate, reliable, and simple scoring system of improving HFMD diagnosis. MATERIAL AND METHODS Based on the following 3 steps, a simple scoring diagnostic system was built: (1) we selected basic markers (age and sex), markers recommended in HFMD diagnosis guidelines, and significant biomarkers among severity groups found in a large dataset; (2) we used positive constituent ratio for determining scores of each marker; and (3) we applied receiving operating curve in an external dataset to determine the optimal cut-off score. RESULTS The selected markers were sex, age, fever, skin rashes, nervous system disorder, respiratory system disorder, digestive system disorder and cardiopulmonary complications, C-reactive-protein, White Blood Cell, Creatinine Kinase, Creatinine Kinase Isoenzyme, Gamma-Glutamyl Transpeptidase, Albumin, Globulin, Albumin/Globulin Ratio, Natrium, Chloride, Calcium, and Glucose. A simple scoring system with 3.9684 as the lower cut-off was constructed. The AUC was 0.918 (95% CI: 0.874-0.963, P<0.01). The sensitivity, specificity, and Youden Index, which were based on the validation dataset of 200 subjects (80 cases, 120 non-cases with skin rashes or fever), were 0.95, 0.90, and 0.85, respectively. CONCLUSIONS This simple scoring system is an effective method to diagnose HFMD.

Hand, foot and mouth disease: current knowledge on clinical manifestations, epidemiology, aetiology and prevention

For a long time, hand, foot and mouth disease (HFMD) was seen as a mild viral infection characterized by typical clinical manifestations that spontaneously resolved in a few days without complications. In the past two decades, HFMD has received new attention because of evidence that this disease could have clinical, epidemiological and aetiological characteristics quite different from those initially thought. In contrast to previous beliefs, it has been clarified that HFMD can be associated with complications, leading to severe neurological sequelae and, rarely, to death. This finding has led to an enormous number of studies that have indicated that several viruses in addition to those known to be causes of HFMD could be associated with the development of disease. Moreover, it was found that if some viruses were more common in some geographic areas, frequent modification of the molecular epidemiology of the infecting strains could lead to outbreaks caused by infectious agents significantly different from those previously circulating. Vaccines able to confer protection against the most common aetiologic agents in a given country have been developed. However, simultaneous circulation of more than one causative virus and modification of the molecular epidemiology of infectious agents make preparations based on a single agent relatively inadequate. Vaccines with multiple components are a possible solution. However, several problems concerning their development must be solved before adequate prevention of severe cases of HFMD can be achieved.

Comprehensive virome analysis reveals the complexity and diversity of the viral spectrum in pediatric patients diagnosed with severe and mild hand-foot-and-mouth disease

The management of hand-foot-and-mouth disease(HFMD) epidemic is difficult due to the frequent emergence of non-EV71 and non-CVA16 enteroviruses and some cases testing negative for HFMD-associated causative agents. To clarify the virus spectrum of mild and severe HFMD, a comprehensive virome analysis of 238 samples was performed using next-generation sequencing (NGS). The data revealed total thirteen mammalian- and plant- virus families and diverse viral populations including enteroviruses, common respiratory viruses, diarrhea-related viruses, plant viruses and anelloviruses. A total of 18 viruses from 7 virus families were identified in severe cases, versus 37 viruses from 12 virus families in mild cases. Moreover, complicated mixed-infections of enteroviruses with common respiratory viruses were mainly found in severe cases(P = 0.013), while diarrhea-related viruses were mainly found in mild cases(P < 0.001). This study provides the preliminary understanding of viromes both in mild and severe cases, which may benefit the detection of etiologic agents and prevention of HFMD.

Severity and burden of hand, foot and mouth disease in Asia: a modelling study

Background

Hand, foot and mouth disease (HFMD) affects millions of children across Asia annually, leading to an increase in implemented control policies such as surveillance, isolation and social distancing in affected jurisdictions. However, limited knowledge of disease burden and severity causes difficulty in policy optimisation as the associated economic cost cannot be easily estimated. We use a data synthesis approach to provide a comprehensive picture of HFMD disease burden, estimating infection risk, symptomatic rates, the risk of complications and death, and overall disability-adjusted life-year (DALY) losses, along with associated uncertainties.

Methods

Complementary data from a variety of sources were synthesised with mathematical models to obtain estimates of severity of HFMD. This includes serological and other data extracted through a systematic review of HFMD epidemiology previously published by the authors, and laboratory investigations and sentinel reports from Singapore's surveillance system.

Results

HFMD is estimated to cause 96 900 (95% CI 40 600 to 259 000) age-weighted DALYs per annum in eight high-burden countries in East and Southeast Asia, with the majority of DALYs attributed to years of life lost. The symptomatic case hospitalisation rate of HFMD is 6% (2.8%-14.9%), of which 18.7% (6.7%-31.5%) are expected to develop complications. 5% (2.9%-7.4%) of such cases are fatal, bringing the overall case fatality ratio to be 52.3 (24.4-92.7) per 100 000 symptomatic infections. In contrast, the EV-A71 case fatality ratio is estimated to be at least 229.7 (75.4-672.1) per 100 000 symptomatic cases. Asymptomatic rate for EV-A71 is 71.4% (68.3%-74.3%) for ages 1-4, the years of greatest incidence.

Conclusion

Despite the high incidence rate of HFMD, total DALY due to HFMD is limited in comparison to other endemic diseases in the region, such as dengue and upper respiratory tract infection. With the majority of DALY caused by years of life lost, it is possible to mitigate most with increased EV-A71 vaccine coverage.

The Epidemiology of Hand, Foot and Mouth Disease in Asia: A Systematic Review and Analysis

CONTEXT

Hand, foot and mouth disease (HFMD) is a widespread pediatric disease caused primarily by human enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16).

OBJECTIVE

This study reports a systematic review of the epidemiology of HFMD in Asia.

DATA SOURCES

PubMed, Web of Science and Google Scholar were searched up to December 2014.

STUDY SELECTION

Two reviewers independently assessed studies for epidemiologic and serologic information about prevalence and incidence of HFMD against predetermined inclusion/exclusion criteria.

DATA EXTRACTION

Two reviewers extracted answers for 8 specific research questions on HFMD epidemiology. The results are checked by 3 others.

RESULTS

HFMD is found to be seasonal in temperate Asia with a summer peak and in subtropical Asia with spring and fall peaks, but not in tropical Asia; evidence of a climatic role was identified for temperate Japan. Risk factors for HFMD include hygiene, age, gender and social contacts, but most studies were underpowered to adjust rigorously for confounding variables. Both community-level and school-level transmission have been implicated, but their relative importance for HFMD is inconclusive. Epidemiologic indices are poorly understood: No supporting quantitative evidence was found for the incubation period of EV-A71; the symptomatic rate of EV-A71/Coxsackievirus A16 infection was from 10% to 71% in 4 studies; while the basic reproduction number was between 1.1 and 5.5 in 3 studies. The uncertainty in these estimates inhibits their use for further analysis.

LIMITATIONS

Diversity of study designs complicates attempts to identify features of HFMD epidemiology.

CONCLUSIONS

Knowledge on HFMD remains insufficient to guide interventions such as the incorporation of an EV-A71 vaccine in pediatric vaccination schedules. Research is urgently needed to fill these gaps.

MA104 Cell line presents characteristics suitable for enterovirus A71 isolation and proliferation

Enterovirus A71 (EV-A71), one of the most important causative agents of hand, foot and mouth disease (HFMD) in children, can lead to severe clinical outcomes, even death. However, the infection spectrum of EV-A71 in different cell lines remains unknown. Therefore, in this study, the biological characteristics of EV-A71 Subgroup C4 in different cell lines were investigated. To this end, the infectivity of EV-A71Jinan1002 isolated from children with severe HFMD was assessed in 18 different host cell lines. It was found that the MA104 cell line displayed biological characteristics suitable for EV-A71 Subgroup C4 strain isolation and proliferation; indeed, it was found that a broad spectrum of cell lines can be infected by EV-A71Jinan1002. Among the screened cells, four cell lines (HEK293, RD, MA104 and Marc145) produced high 50% tissue culture infective dose (TCID50 ) values calculated in viral proliferations (ranged from 10(7.6) to 10(7.8) ); the TCID50 being negatively associated with the time to appearance of CPE. Proliferation curves demonstrated that EV-A71Jinan1002 amplifies more efficiently in MA104, Hep-2 and RD cells. Remarkably, the virus isolation rate was much higher in MA104 cells than in RD cells. Thus this study, to our knowledge, is for the first to explore the infection spectrum of EV-A71 subgroup C4 in such a large number of different cell lines. Our data provide useful reference data for facilitating further study of EV-A71.

Performance of reversed transcription loop-mediated isothermal amplification technique detecting EV71: a systematic review with meta-analysis

Human enterovirus 71 (EV71) is the major etiological agent of hand, foot and mouth disease (HFMD), which is a common infectious disease in young children. Studies in the past have shown that reversed transcription loop-mediated isothermal amplification (RT-LAMP) was a rapid approach for the detection of EV71 in HFMD. This meta-analysis study is to evaluate the diagnostic role of RT-LAMP in detecting EV71 infection. A comprehensive literature research of PubMed, Embase, Wan Fang Data, and Chinese National Knowledge Infrastructure databases was conducted on articles aiming at the diagnostic performance of RT-LAMP in EV71 detection published before February 10, 2014. Data from selected studies were pooled to yield the summary sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), diagnostic odds ratio (DOR), and receiver operating characteristic (SROC) curve by using STATA VERSION 12.0 software. Ten studies including a total of 907 clinical samples were of high quality in this meta-analysis. Overall, the pooled sensitivity, specificity, PLR, NLR, DOR, and the area under the SROC curve was 0.99 (0.97, 1.00), 0.97 (0.94, 1.00), 5.90 (95% CI: 3.90-8.94), 0.20 (95% CI: 0.14-0.29), and 1.00 (95% CI: 0.99-1.00), respectively. The univariate analysis of potential variables showed some changes in the diagnostic performance, but none of the differences reached statistical significance. Despite inter-study variability, the test performance of RT-LAMP was consistent with real-time RT-PCR in detecting EV71. This meta-analysis suggests that RT-LAMP is a useful diagnostic tool with high sensitivity and specificity for detecting EV71.

Serum inflammatory cytokine levels correlate with hand-foot-mouth disease severity: a nested serial case-control study

Background

Hand-food-mouth disease (HFMD) cases can be fatal. These cases develop rapidly, and it is important to predict the severity of HFMD from mild to fatal and to identify risk factors for mild HFMD. The objective of this study was to correlate the levels of serum inflammatory cytokines with HFMD severity.

Methods

This study was designed as a nested serial case-control study. The data collected included general information, clinical symptoms and signs, laboratory findings and serum cytokine levels.

Results

The levels of IL-4, IL-6, IL-10, TNF-α and IFN-γ in patients with severe HFMD were significantly higher than in mild patients during the 2nd to 5th day after disease onset. The levels of IL-4, IL-6, IL-10 and IFN-γ increased from the 2nd day to the 4th day and later decreased. The levels of TNF-α were high on the first two days and subsequently decreased. The changes of IL-10, TNF-α and IFN-γ in the controls were similar for all cases. The levels of IL-4, IL-6 and IL-17 in the controls were not significantly different with the progression of HFMD.

Conclusions

Our findings indicate that the IL-4, IL-6, IL-10, TNF-α and IFN-γ levels correlate with HFMD severity.

Coxsackievirus A16: epidemiology, diagnosis, and vaccine

Coxsackievirus 16 (CA16) is one of the major pathogens associated with hand, foot, and mouth disease (HFMD) in infants and young children. In recent years, CA16 and human enterovirus 71 (EV71) have often circulated alternatively or together in the Western Pacific region, which has become an important public health problem in this region. HFMD caused by CA16 infection is generally thought to be mild and self-limiting. However, recently several severe and fatal cases involving CA16 have been reported. Studies have shown that co-infection with CA16 and EV71 can cause serious complications in the central nervous system (CNS) and increase the chance of genetic recombination, which may be responsible for the large HFMD outbreak in Mainland China in 2008. For these reasons, recent studies have focused on the virological characteristics of CA16 and the development of CA16-related diagnostic reagents and vaccines.