Epidemiological and aetiological characteristics of hand, foot, and mouth disease in Shijiazhuang City, Hebei province, China, 2009-2012

Genomic epidemiology of CVA10 in Guangdong, China, 2013-2021

Hand, Foot and Mouth Disease (HFMD) is a highly contagious viral illness primarily affecting children globally. A significant epidemiological transition has been noted in mainland China, characterized by a substantial increase in HFMD cases caused by non-Enterovirus A71 (EV-A71) and non-Coxsackievirus A16 (CVA16) enteroviruses (EVs). Our study conducts a retrospective examination of 36,461 EV-positive specimens collected from Guangdong, China, from 2013 to 2021. Epidemiological trends suggest that, following 2013, Coxsackievirus A6 (CVA6) and Coxsackievirus A10 (CVA10) have emerged as the primary etiological agents for HFMD. In stark contrast, the incidence of EV-A71 has sharply declined, nearing extinction after 2018. Notably, cases of CVA10 infection were considerably younger, with a median age of 1.8 years, compared to 2.3 years for those with EV-A71 infections, possibly indicating accumulated EV-A71-specific herd immunity among young children. Through extensive genomic sequencing and analysis, we identified the N136D mutation in the 2 A protein, contributing to a predominant subcluster within genogroup C of CVA10 circulating in Guangdong since 2017. Additionally, a high frequency of recombination events was observed in genogroup F of CVA10, suggesting that the prevalence of this lineage might be underrecognized. The dynamic landscape of EV genotypes, along with their potential to cause outbreaks, underscores the need to broaden surveillance efforts to include a more diverse spectrum of EV genotypes. Moreover, given the shifting dominance of EV genotypes, it may be prudent to re-evaluate and optimize existing vaccination strategies, which are currently focused primarily target EV-A71.

Potential relevance of salivary legumain for the clinical diagnostic of hand, foot, and mouth disease

The fight against hand, foot, and mouth disease (HFMD) remains an arduous challenge without existing point-of-care (POC) diagnostic platforms for accurate diagnosis and prompt case quarantine. Hence, the purpose of this salivary biomarker discovery study is to set the fundamentals for the realization of POC diagnostics for HFMD. Whole salivary proteome profiling was performed on the saliva obtained from children with HFMD and healthy children, using a reductive dimethylation chemical labeling method coupled with high-resolution mass spectrometry-based quantitative proteomics technology. We identified 19 upregulated (fold change = 1.5-5.8) and 51 downregulated proteins (fold change = 0.1-0.6) in the saliva samples of HFMD patients in comparison to that of healthy volunteers. Four upregulated protein candidates were selected for dot blot-based validation assay, based on novelty as biomarkers and exclusions in oral diseases and cancers. Salivary legumain was validated in the Singapore (n = 43 healthy, 28 HFMD cases) and Taiwan (n = 60 healthy, 47 HFMD cases) cohorts with an area under the receiver operating characteristic curve of 0.7583 and 0.8028, respectively. This study demonstrates the feasibility of a broad-spectrum HFMD POC diagnostic test based on legumain, a virus-specific host systemic signature, in saliva.

Epidemiological and etiological characteristics of mild hand, foot and mouth disease in children under 7 years old, Nanjing, China, 2010-2019

Background

Mild hand, foot and mouth disease (HFMD) cases make up a relatively high proportion of HFMD while have often been overlooked. This study aimed to investigate the epidemiological and etiological characteristics of mild HFMD in Nanjing.

Methods

Data on mild HFMD cases, during 2010–2019 in Nanjing, were collected from the China Information System for Disease Control and Prevention. This study mainly focused on mild cases aged < 7 years. Descriptive analysis was used to summarize epidemiological and etiological characteristics of mild cases. Flexible spatial scan statistic was used to detect spatial clusters of mild cases.

Results

A total of 175,339 mild cases aged < 7 years were reported, accounting for 94.4% of all mild cases. There was a higher average annual incidence of mild HFMD in children aged < 7 years (4,428 cases/100,000) compared with children aged ≥ 7 years (14 cases/100,000, P < 0.001), and especially children aged 1-year-old (7,908 cases/100,000). Mild cases showed semi-annual peaks of activity, including a major peak (April to July) and a minor peak (September to November). The average annual incidence was higher in males (5,040 cases/100,000) than females (3,755 cases/100,000). Based on the cumulative reported cases, the most likely cluster was detected, including Yuhuatai District, Jiangning District, Jiangbei new Area, and Pukou District. The annual distribution of enterovirus serotypes showed a significant difference. During 2010–2016, Enterovirus 71 (EV71), Coxsackievirus A16 (Cox A16), and other non-EV71/Cox A16 EVs, accounted for 29.1%, 34.6%, 36.3% of all the enterovirus test positive cases, respectively. Moreover, during 2017–2019, Cox A6, Cox A16, EV71, and other non-EV71/Cox A16/Cox A6 EVs, accounted for 47.3%, 32.5%, 10.7%, 9.5%, respectively.

Conclusions

Children under 7 years old are at higher risk of mild HFMD. Regions with high risk are mainly concentrated in the areas surrounding central urban areas. Cox A16 and Cox A6 became the dominant serotypes and they alternated or were co-epidemic. Our findings could provide valuable information for improving the regional surveillance, prevention and control strategies of HFMD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-022-00974-4.

Epidemiological characteristics of hand, foot, and mouth disease clusters during 2016-2020 in Beijing, China

Hand, foot, and mouth disease (HFMD) is an infectious disease that usually occurs in children under 5 years and is caused by a group of enteroviruses. This study aimed to investigate the epidemiological characteristics of HFMD clusters from 2016 to 2020 in Tongzhou, Beijing, and explored the genetic evolution of CV-A6. The HFMD case information came from the Information System of China Center for Disease Control and Prevention (CDC), as well as the clusters information verification and on-site investigation by Tongzhou CDC. ARIMA model was applied to forecast HFMD clusters in 2020. Totally 440 HFMD clusters were reported during 2016-2020. The large peak of the clusters occurred in April-July, followed by a smaller peak in October-November during 2016-2019. However, in 2020, the two peaks disappeared. The main site of HFMD clusters was childcare facilities (65.0%) and mostly occurred in urban areas (46.1%). The detection rate of CV-A6 was the highest (36.1%), and cases with CV-A6 infection had the highest proportion of fever. The phylogenetic analysis based on CV-A6 VP1 gene showed that the predominant strains mainly located in Group F during 2016-2017, while changed into Group A during 2018-2020. HFMD clusters presented seasonality, mainly located in childcare facilities and urban areas, and CV-A6 was the major causative agent. Targeted prevention and control measures should be taken to reduce HFMD clusters.

Genomic surveillance of coxsackievirus A10 reveals genetic features and recent appearance of genogroup D in Shanghai, China, 2016–2020

Coxsackievirus A10 (CVA10) is one of the major causative agents of hand, foot and mouth disease (HFMD). To investigate the epidemiological characteristics as well as genetic features of CVA10 currently circulating in Shanghai, China, we collected a total of 9,952 sporadic HFMD cases from January 2016 to December 2020. In the past five years, CVA10 was the fourth prevalent causatives associated with HFMD in Shanghai and the overall positive rate was 2.78%. The annual distribution experienced significant fluctuations over the past five years. In addition to entire VP1 sequencing, complete genome sequencing and recombination analysis of CVA10 isolates in Shanghai were further performed. A total of 64 near complete genomes and 11 entire VP1 sequences in this study combined with reference sequences publicly available were integrated into phylogenetic analysis. The CVA10 sequences in this study mainly belonged to genogroup C and presented 91%–100% nucleotide identity with other Chinese isolates based on VP1 region. For the first time, our study reported the appearance of CVA10 genogroup D in Chinese mainland, which had led to large-scale outbreaks in Europe previously. The recombination analysis showed the recombination break point located between 5,100 nt and 6,700 nt, which suggesting intertypic recombination with CVA16 genogroup D. To conclusion, CVA10 genogroup C was the predominant genogroup in Shanghai during 2016–2020. CVA10 recombinant genogroup D was firstly reported in circulating in Chinese mainland. Continuous surveillance is needed to better understand the evolution relationships and transmission pathways of CVA10 to help to guide disease control and prevention.

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Systematic profiles of genetic features of CVA10 near complete genome.

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First report of the appearance of CVA10 genogroup D in Chinese mainland.

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Genomic comparisons indicate the potential recombinant origin of CVA10 genogroup D.

Evaluation of the cross-neutralization activities elicited by Coxsackievirus A10 vaccine strains

Increased severity of diseases caused by Coxsackievirus A10 (CV-A10) as well as a large number of mutants and recombinants circulating in the population are a cause of concern for public health. A vaccine with broad-spectrum and homogenous protective capacity is needed to prevent outbreaks of CV-A10. Here, we evaluated cross-neutralization of prototype strain and 17 CV-A10 strains from related manufacturers in mainland China in vitro using 30 samples of plasma collected from naturally infected human adults and 18 sera samples from murine immunized with the above strains of CV-A10. Both human plasma and murine sera exhibited varying degrees of cross-neutralizing activities. Prototype A/Kowalik and sub-genotype C3/S113 were most difficult to neutralize. Among all strains tested, neutralization of S102 and S108 strains by 18 different sera was the most uniform, suggesting their suitability for detection of NtAb titers of different vaccines for avoiding biases introduced by detection strain. Furthermore, among all immune-sera, cross-neutralization of the 18 strains of CV-A10 by anti-S110 and anti-S102 was the most homogenous. Anti-S102 exhibiting higher geometric mean titer (GMT) in vitro was evaluated for its cross-protection capacity in vivo. Remarkably, administration of anti-S102 protected mice from lethal dosage of eight strains of CV-A10. These results provide a framework for formulating strategies for the R&D of vaccines targeting CV-A10 infections.

Characterization of coxsackievirus A10 strains isolated from children with hand, foot, and mouth disease

Hand, foot, and mouth disease (HFMD) is a contagious disease that threatens the health of children under 5 years of age. Coxsackievirus A10 (CV-A10) is one of the main pathogens of HFMD. Currently, preventive vaccines and specific therapeutic drugs are not available for CV-A10. In this study, a total of 327 stool specimens were collected from pediatric patients from 2009 to 2017 during HFMD surveillance, among which 14 CV-A10 strains could only be isolated from RD cells, but not from KMB17 and Vero cells. Through adaptive culture, two and 11 CV-A10 strains were recovered from Vero and KMB17 cell cultures, respectively. The growth of CV-A10 strains in Vero cells was better than that in KMB17 cells. The 14 CV-A10 strains belonged to the F genotype, and the nucleotides and amino acids of their complete genomes shared 92.6% - 96.3% and 98.4 - 98.9% identities, respectively. The different CV-A10 strains exhibited varying virulence in vivo, but had similar effects on tissue injury, with the hind limb muscles, kidneys, and lungs being severely affected. Additionally, the hind limb muscles had the highest viral loads. CV-A10 was found to exhibit strong tropism to muscle tissue. The results of this study are critical to developing vaccines against CV-A10 infections. This article is protected by copyright. All rights reserved.

Nonlinear effect of temperature on hand, foot, and mouth disease in Lanzhou, China

To examine the effects of temperature on the daily cases of hand, foot, and mouth disease (HFMD).Data on the daily cases of HFMD in Lanzhou from 2008 to 2015 were obtained, and meteorological data from the same period were collected. A distributed lag nonlinear model was fitted to reveal the relationship between the daily mean temperature and the daily cases of HFMD.From 2008 to 2015, 25,644 cases were reported, of which children under 5 years of age accounted for 78.68% of cases. The highest peak of HFMD cases was usually reported between April to July each year. An inverse V-shaped relationship was observed between daily mean temperature and HFMD cases; a temperature of 18°C was associated with a maximum risk of HFMD. The relative risk (RR) was 1.57 (95% confidence interval: 1.23-1.23), and boys and children aged 3 to 5 years were populations with the highest risk. The cumulative risks of high temperature (20.2°C and 25.2°C) in the total, age-specific, and gender-specific groups peaked on lag 14 days; RR was higher in girls than in boys and in children aged 1 to 2 years than in other age groups. However, the effects of low temperature (-5.3°C, 2.0°C, and 12.8°C) were not significant for both gender-specific and age-specific patients.High temperature may increase the risk of HFMD, and boys and children aged 3 to 5 years were at higher risks on lag 0 day; however, the cumulative risks in girls and children aged 1 to 2 years increased with the increasing number of lag days.

Genetic characterization of VP1 of coxsackieviruses A2, A4, and A10 associated with hand, foot, and mouth disease in Vietnam in 2012-2017: endemic circulation and emergence of new HFMD-causing lineages

While conducting sentinel surveillance of hand, foot, and mouth disease (HFMD) in Vietnam, we found a sudden increase in the prevalence of coxsackievirus A10 (CV-A10) in 2016 and CV-A2 and CV-A4 in 2017, the emergence of which has been reported recently to be associated with various clinical manifestations in other countries. However, there have been only a limited number of molecular studies on those serotypes, with none being conducted in Vietnam. Therefore, we sequenced the entire VP1 genes of CV-A10, CV-A4, and CV-A2 strains associated with HFMD in Vietnam between 2012 and 2017. Phylogenetic analysis revealed a trend of endemic circulation of Vietnamese CV-A10, CV-A4, and CV-A2 strains and the emergence of thus-far undescribed HFMD-causing lineages of CV-A4 and CV-A2. The Vietnamese CV-A10 strains belonged to a genotype comprising isolates from patients with HFMD from several other countries; however, most of the Vietnamese strains were grouped into a local lineage. Recently, emerging CV-A4 strains in Vietnam were grouped into a unique lineage within a genotype comprising strains isolated from patients with acute flaccid paralysis from various countries. New substitutions were detected in the putative BC and HI loops in the Vietnamese CV-A4 strains. Except for one strain, Vietnamese CV-A2 isolates were grouped into a unique lineage of a genotype that includes strains from various countries that are associated with other clinical manifestations. Enhanced surveillance is required to monitor their spread and to specify their roles as etiological agents of HFMD or "HFMD-like" diseases, especially for CV-A4 and CV-A2. Further studies including whole-genome sequencing should be conducted to fully understand the evolutionary changes occurring in these newly emerging strains.

Hand, foot, and mouth disease associated with coxsackievirus A10: more serious than it seems

INTRODUCTION

Hand, foot, and mouth disease (HFMD) is a common viral childhood illness, that has been a severe public health concern worldwide, particularly in the Asia-Pacific region. According to epidemiological data of HFMD during the past decade, the most prevalent causal viruses were enterovirus (EV)-A71, coxsackievirus (CV)-A16, CV-A6, and CV-A10. The public health burden of CV-A10-related diseases has been underestimated as their incidence was lower than that of EV-A71 and CV-A16 in most HFMD outbreaks. However, cases of CV-A10 infection are more severe, and its genome is more variable, which has alerted the research community worldwide. Areas covered: In this paper, studies on the epidemiology, laboratory diagnosis, clinical manifestations, molecular epidemiology, seroepidemiology, animal models of CV-A10, and vaccines and antiviral strategies against this genotype are reviewed. In addition, the genetic evolution of circulating strains was analyzed. Expert opinion: Multivalent vaccines against EV-A71, CV-A16, CV-A6, and CV-A10 should be a next-step HFMD vaccine strategy.

The emerging sub-genotype C2 of CoxsackievirusA10 Associated with Hand, Foot and Mouth Disease extensively circulating in mainland of China

Coxsackievirus A10 (CV-A10) associated with Hand, foot, and mouth disease (HFMD) cases emerged increasingly in recent years. In this study, the samples from nation-wide HFMD surveillance, including 27 out of 31 provinces in China were investigated, and the continuous and extensive virological surveillance, covered 13 years, were conducted to provide a comprehensive molecular characterization analysis of CV-A10. 855 CV-A10 viruses (33 severe cases included), were isolated from HFMD children patients during 2009 to 2016 in China. 164 representative sequences from these viruses, together with 117 CV-A10 sequences downloaded from GenBank based on entire VP1 were recruited in this study. Two new genotypes (F and G) and two sub-genotypes (C1 and C2) were identified. Among 264 Chinese sequences, 9 of them were genotype B, 8 of them were C1, and the other (247) were C2, the predominant sub-genotype in China since 2012. Chinese C2 viruses showed obvious temporal characteristics and can be divided into 3 clusters (cluster 1~3). Cluster 3 viruses was circulating extensively during 2014 and 2016 with more severe cases. It is very necessary and important to continuously conduct the extensive virological surveillance for CV-A10, and further evolutionary studies will provide more evidence on its evolution and virulence.

Molecular characteristics of hand, foot, and mouth disease for hospitalized pediatric patients in Yunnan, China

Hand, foot, and mouth disease (HFMD) is a common infectious disease caused by multiple enteroviruses (EVs) in China. To better define the etiologic agents and clinical characteristics of HFMD, we conducted this study in Yunnan, China.In this study, 1280 stool specimens were collected from pediatric patients hospitalized for treatment of HFMD in 2010. EV was detected with nested reverse transcription polymerase chain reaction and directly genotyped by gene sequencing of the viral protein 1 (VP1) region. Phylogenetic analysis was performed based on the VP1 partial gene and the clinical characteristics were analyzed using SPSS Software.Of 1280 specimens, 1115 (87.1%) tested positive for EV. Seventeen different EV serotypes were detected. Coxsackievirus A16 (CA16) was the most frequently detected serotype (615/1115 cases, 55.1%), followed by enterovirus 71 (EV71; 392/1115, 35.2%), CA10 (45/1115, 4.0%), and CA4 (23/1115, 2.1%). Among the 709 severe cases, CA16, EV71, CA10, and CA4 accounted for 48.0%, 42.0%, 3.5%, and 2.3%, respectively. Of the 26 critical cases, 13 were caused by EV71, 9 by CA16, 2 by CA4, and 1 each were the result of CA10 and E9, respectively. All EV71, CA16, CA10, and CA4 isolates were highly homologous to the strains isolated from mainland China, and belonged to the C4a, B1a, G, and C genotypes, respectively.Our study showed that EV71 and CA16 were the main causative agents for severe and critical HFMD, but other serotypes can also cause severe and critical cases.

Large-Scale Survey of Human Enteroviruses in Wastewater Treatment Plants of a Metropolitan Area of Southern Italy

Human enteroviruses (HEVs) occur in high concentrations in wastewater and can contaminate receiving environmental waters, constituting a major cause of acute waterborne disease worldwide. In this study, we investigated the relative abundance, occurrence, and seasonal distribution of polio and other enteroviruses at three wastewater treatment plants (WWTPs) in Naples, Southern Italy, from January 2010 to December 2014. Influent and effluent samples from the three WWTPs were collected monthly. One hundred and sixty-one of the 731 wastewater samples collected (22.0%) before and after water treatment were CPE positive on RD cells; while no samples were positive on L20B cells from any WWTPs. Among the 140 non-polio enterovirus isolated from inlet sewage, 69.3% were Coxsackieviruses type B and 30.7% were Echoviruses. Among these, CVB3 and CVB5 were most prevalent, followed by CVB4 and Echo6. The twenty-one samples tested after treatment contained 6 CVB4, 5 CVB3, 3 Echo11, and 2 Echo6; while other serotypes were isolated less frequently. Data on viral detection in treated effluents of WWTPs confirmed the potential environmental contamination by HEVs and could be useful to establish standards for policies on wastewater management.

The dynamics of the hand, foot and mouth disease epidemic from 2008 to 2016 in Zhenjiang city, China

AIM

To investigate the hand, foot and mouth disease (HFMD) epidemic in Zhenjiang, China from 2008 to 2016.

MATERIALS & METHODS

A total of 37,202 HFMD cases were investigated and 3707 nasopharyngeal swabs were detected for enterovirus RNA using RT-quantitative PCR.

RESULTS

We first reported a mixed pattern of HFMD seasonal epidemic with a combination of single-peak and two-peak patterns in alternate years, and the occurrence of sporadic and epidemic outbreaks of HFMD in kindergartens in Zhenjiang. Children younger than 4 years of age were highly vulnerable to HFMD, and home children and boys had higher risk to develop severe HFMD than nursery children and girls, respectively. Among tested samples, 1709 (46.1%) were detected as enterovirus RNA positive.

CONCLUSION

This study first presents the dynamic of the HFMD epidemic in Zhenjiang from 2008 to 2016.

An emerging and expanding clade accounts for the persistent outbreak of Coxsackievirus A6-associated hand, foot, and mouth disease in China since 2013

Enterovirus (EV)-A71 and Coxsackievirus (CV)-A16 have historically been the major pathogens of hand, foot, and mouth disease (HMFD) in China; however, CV-A6， which had previously received little attention, became the predominant pathogen in 2013, and has remained one of the common pathogens since then. In this work, we conducted a molecular epidemiology study of CV-A6-associated HFMD in Xiamen from 2009 to 2015. The data showed CV-A6 pandemics had a certain periodicity rather than occurring randomly. Evolution analysis based on near-complete VP1 nucleotide sequences showed subgenotype D5 lineage 4 strains account for the persistent outbreak of CV-A6-associated HFMD in China since 2013. Alignment analysis revealed eight candidate amino acid substitutions in VP1, which may provide useful information for the research of CV-A6 virulence enhancement. This study contributed to elucidating the circulation patterns and genetic characteristics of CV-A6 in China; however, further surveillance and intervention in CV-A6 epidemics is recommended.

Epidemiological and genetic characteristics of EV71 in hand, foot, and mouth disease in Guangxi, southern China, from 2010 to 2015

Hand, foot, and mouth disease (HFMD) is a significant public health challenge in China. Human enterovirus 71 (EV71) is regarded as the predominant causative pathogen of HFMD. Since 2015, two inactivated EV71 vaccines have been approved in mainland China, and because their use could change the HFMD pathogen spectrum, this should now be monitored. However, the epidemiological and genetic trends of EV71 with respect to HFMD in Guangxi, southern China, are still not clear. In this study, we describe the epidemiological and genetic characterization of this virus in clinically-diagnosed HFMD reported from 2010 to 2015 in Guangxi. Data showed that a two-year epidemic cycle, with a predominance of EV71 infections, contributed to HFMD outbreaks in Guangxi. Furthermore, this virus is a major causative agent of severe and fatal HFMD. Interestingly, in Guangxi, EV71-positive rates tended to decrease over time. In particular, EV71-positive rates were found in Fangchenggang city, which reported very few severe and fatal cases over the six-year period. Phylogenetic analysis of the VP1 gene revealed that the major circulating strains belonged exclusively to genotype C, subtype 4a (C4a), and most clustered with strains circulating in southern China. The most interesting finding was that a strain isolated in 2012 clustered with Vietnamese strains isolated from 2011–2012. The data highlight the importance of pathogen surveillance for HFMD in China, especially Guangxi, which is located on the border of China and the Association of Southeast Asian Nations.