Impact of meteorological factors on the incidence of hand-foot-mouth disease in Yangzhou from 2017 to 2022: a time series study

Background

Hand, foot, and mouth disease (HFMD) is a significant public health issue in China, and numerous studies have indicated a close association between HFMD incidence and meteorological factors. This study aims to investigate the relationship between meteorological factors and HFMD in Yangzhou City, Jiangsu Province, China.

Methods

HFMD case reports and meteorological data from Yangzhou City between 2017 and 2022 were extracted from the National Notifiable Infectious Disease Surveillance System and the Meteorological Data Sharing Service System, respectively. A generalized additive model (GAM) was employed to assess the exposure-response relationship between meteorological factors and HFMD. Subsequently, a distributed lag nonlinear model (DLNM) was used to explore the exposure-lag-effect of meteorological factors on HFMD.

Results

HFMD in Yangzhou City exhibits obvious seasonality and periodicity. There is an inverted "U" shaped relationship between average temperature and the risk of HFMD, with the maximum lag effect observed at a temperature of 25°C with lag 0 day (RR = 2.07, 95% CI: 1.74-2.47). As the duration of sunshine and relative humidity increase, the risk of HFMD continuously rises, with the maximum lag effect observed at a sunshine duration of 12.4 h with a lag of 14 days (RR = 2.10, 95% CI: 1.17-3.77), and a relative humidity of 28% with a lag of 14 days (RR = 1.21, 95% CI: 1.01-1.64). There is a "U" shaped relationship between average atmospheric pressure and the risk of HFMD, with the maximum effect observed at an atmospheric pressure of 989 hPa with no lag (RR = 1.45, 95% CI: 1.25-1.69). As precipitation increases, the risk of HFMD decreases, with the maximum effect observed at a precipitation of 151 mm with a lag of 14 days (RR = 1.45, 95% CI: 1.19-2.53).

Conclusion

Meteorological factors including average temperature, average atmospheric pressure, relative humidity, precipitation, and sunshine duration significantly influenced the risk of HFMD in Yangzhou City. Effective prevention measures for HFMD should be implemented, taking into account the local climate conditions.

Immune Efficacy of the EV71 Vaccine in Fujian Province, China: A Real-World Analysis of HFMD

EV71 vaccine immunization mainly protects the human population against severe and fatal HFMD and has a positive effect on reducing the overall incidence rates of HFMD and of hospitalized cases. In the analysis of data collected over 4 years, we compared HFMD's incidence rate, severity, and etiological changes in a target population before and after vaccine intervention. The incidence rate of HFMD decreased from 39.02‱ in 2014 to 11.02‱ in 2021, with a decrease rate of 71.7%, and the decrease was statistically significant (p < 0.001). The number of hospitalized cases decreased by 68.88%, the number of severe cases dropped by 95.60% and the number of deaths dropped to 0. The proportion of cases caused by the EV71 virus in different populations decreased significantly after the intervention, specifically, by 68.41% among individuals 0-4 years of age, by 74.32% among kindergarten children, by 86.07% in severe cases and by 100% with respect to the number of deaths.

Laboratory Indicators for Identifying Hand, Foot, and Mouth Disease Severity: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study is to study laboratory indicators for the identification of hand, foot, and mouth disease (HFMD) severity.

METHODS

We searched PubMed, Embase, and the Web of Science for literature that was published before May 2022. The main results are presented as forest plots. Subgroup analyses, sensitivity analyses, and publication bias were also performed.

RESULTS

Our study indicated that white blood cells (WBC) (95%CI: 0.205-0.778), blood glucose (95%CI: 0.505-0.778), lymphocytes (95%CI: 0.072-0.239), creatinine (95%CI: 0.024-0.228), interleukin (IL)-2 (95%CI: 0.192-1.642), IL-6 (95%CI: 0.289-0.776), IL-8 (95%CI: 0.499-0.867), IL-10 (95%CI: 0.226-0.930), interferon-γ (IFN-γ) (95%CI: 0.193-2.584), tumor necrosis factor-α (TNF-α) (95%CI: 1.078-2.715), and creatine kinase MB isoenzyme (CK-MB) (95%CI: 0.571-1.459) were associated with an increased risk of HFMD severity, and the results of the sensitivity analysis of these indicators were stable and free of publication bias.

CONCLUSIONS

Our results suggest that various deleterious immune and metabolic changes can increase the risk of HFMD severity, which can provide a basis for predicting the prognosis and useful evidence for clinicians to manage patients efficiently.

The impact of enterovirus A71 vaccination program on hand, foot, and mouth disease in Guangdong, China:a longitudinal surveillance study

Enterovirus A71 (EV71) vaccination program was introduced in 2016 in China. Based on a longitudinal surveillance dataset from 2012 to 2019 in Guangdong, China, we estimated the impact of the EV71 vaccination program on hand, foot, and mouth disease (HFMD) incidence, by using a counterfactual prediction made from synthetic control approach integrated with a Bayesian time-series model. We observed a relative reduction of 41.4% for EV71-associated HFMD cases during the post-vaccination period of 2017-2019, corresponding to 26,226 cases averted. The reduction of EV71-associated HFMD cases raised with the elevation of EV71 vaccine coverage by year. We found an indirect effect for the children aged 6-14 years who were less likely to be vaccinated. Whereas, the EV71 vaccine may not protect against non-EV71-associated HFMD. This study provides a template for ongoing public health surveillance of EV71 vaccine effectiveness with a counterfactual study design. Our results show strong evidence of the EV71 vaccination program working on reducing EV71-associated HFMD in real-world settings. The finding will benefit policy-making of EV71 vaccination and the prevention of HFMD.

Multiple molecular characteristics of circulating enterovirus types among pediatric hand, foot and mouth disease patients after EV71 vaccination campaign in Wuxi, China

The molecular properties of the circulating causative agents of hand, foot and mouth disease (HFMD) in Wuxi remain unclear, posing diagnostic and prevention challenges. Additionally, in several regions of mainland China, the EV71 immunisation drastically reduced related cases and altered the HFMD pathogen spectrum, while the precise situation in Wuxi remained unknown. To address these issues, paediatric HFMD cases diagnosed in the clinic were enrolled and anal swabs were acquired in the spring of 2019. The 5′-UTR and VP1 genes were interpreted using RT-nPCR with degenerate primers to confirm their genotypes. Following that, the entire genome sequences of each viral type were recovered, allowing for the interpretation of several molecular properties. A total of 249 clinically confirmed HFMD cases had their anal swabs taken for viral identification, from which the genome sequences of seven genotypes were recovered. Coxsackievirus A16 is the most prevalent type, followed by Coxsackievirus A6, A10, A2, A4, A5 and Echovirus 11, all of which were genetically determined for the first time in Wuxi. Phylogenetic and recombination analyses were used to evaluate their evolutionary relationships with other strains found in other regions. Noticeably, a CVA16 subtype, responsible for a large proportion of the observed cases, phylogenetically clustered within clade B1a along with some strains from other countries, was the first one to be reported in China. Furthermore, some recombination events were inferred from strains detected in sporadic cases, particularly the recombination between CVA2 and CVA5 strains. Our investigation elucidated the multiple molecular characteristics of the HFMD causal enterovirus strains in Wuxi, underlining the potential hazards associated with these circulating viral types in the population and aiding in future surveillance and prevention of this disease.

Does enterovirus 71 urge for effective vaccine control strategies? Challenges and current opinion

Enterovirus 71 (EV71) is an infectious virus affecting all age groups of people around the world. It is one of the major aetiologic agents for HFMD (hand, foot and mouth disease) identified globally. It has led to many outbreaks and epidemics in Asian countries. Infection caused by this virus that can lead to serious psychological problems, heart diseases and respiratory issues in children younger than 10 years of age. Many studies are being carried out on the pathogenesis of the virus, but little is known. The host immune response and other molecular responses against the virus are also not clearly determined. This review deals with the interaction between the host and the EV71 virus. We discuss how the virus makes use of its proteins to affect the host's immunity and how the viral proteins help their replication. Additionally, we describe other useful resources that enable the virus to evade the host's immune responses. The knowledge of the viral structure and its interactions with host cells has led to the discovery of various drug targets for the treatment of the virus. Additionally, this review focusses on the antiviral drugs and vaccines developed by targeting various viral surface molecules during their infectious period. Furthermore, it is asserted that the improvement of prevailing vaccines will be the simplest method to manage EV71 infection swiftly. Therefore, we summarise numerous vaccines candidate for the EV71, such as the use of an inactivated complete virus, recombinant VP1 protein, artificial peptides, VLPs (viral-like particles) and live attenuated vaccines for combating the viral outbreaks promptly.

Molecular Docking of SP40 Peptide towards Cellular Receptors for Enterovirus 71 (EV-A71)

Enterovirus 71 (EV-A71) is one of the predominant etiological agents of hand, foot and mouth disease (HMFD), which can cause severe central nervous system infections in young children. There is no clinically approved vaccine or antiviral agent against HFMD. The SP40 peptide, derived from the VP1 capsid of EV-A71, was reported to be a promising antiviral peptide that targeted the host receptor(s) involved in viral attachment or entry. So far, the mechanism of action of SP40 peptide is unknown. In this study, interactions between ten reported cell receptors of EV-A71 and the antiviral SP40 peptide were evaluated through molecular docking simulations, followed by in vitro receptor blocking with specific antibodies. The preferable binding region of each receptor to SP40 was predicted by global docking using HPEPDOCK and the cell receptor-SP40 peptide complexes were refined using FlexPepDock. Local molecular docking using GOLD (Genetic Optimization for Ligand Docking) showed that the SP40 peptide had the highest binding score to nucleolin followed by annexin A2, SCARB2 and human tryptophanyl-tRNA synthetase. The average GoldScore for 5 top-scoring models of human cyclophilin, fibronectin, human galectin, DC-SIGN and vimentin were almost similar. Analysis of the nucleolin-SP40 peptide complex showed that SP40 peptide binds to the RNA binding domains (RBDs) of nucleolin. Furthermore, receptor blocking by specific monoclonal antibody was performed for seven cell receptors of EV-A71 and the results showed that the blocking of nucleolin by anti-nucleolin alone conferred a 93% reduction in viral infectivity. Maximum viral inhibition (99.5%) occurred when SCARB2 was concurrently blocked with anti-SCARB2 and the SP40 peptide. This is the first report to reveal the mechanism of action of SP40 peptide in silico through molecular docking analysis. This study provides information on the possible binding site of SP40 peptide to EV-A71 cellular receptors. Such information could be useful to further validate the interaction of the SP40 peptide with nucleolin by site-directed mutagenesis of the nucleolin binding site.

Coxsackievirus A2 Leads to Heart Injury in a Neonatal Mouse Model

Coxsackievirus A2 (CVA2) has emerged as an active pathogen that has been implicated in hand, foot, and mouth disease (HFMD) and herpangina outbreaks worldwide. It has been reported that severe cases with CVA2 infection develop into heart injury, which may be one of the causes of death. However, the mechanisms of CVA2-induced heart injury have not been well understood. In this study, we used a neonatal mouse model of CVA2 to investigate the possible mechanisms of heart injury. We detected CVA2 replication and apoptosis in heart tissues from infected mice. The activity of total aspartate transaminase (AST) and lactate dehydrogenase (LDH) was notably increased in heart tissues from infected mice. CVA2 infection also led to the disruption of cell-matrix interactions in heart tissues, including the increases of matrix metalloproteinase (MMP)3, MMP8, MMP9, connective tissue growth factor (CTGF) and tissue inhibitors of metalloproteinases (TIMP)4. Infiltrating leukocytes (CD45⁺ and CD11b⁺ cells) were observed in heart tissues of infected mice. Correspondingly, the expression levels of inflammatory cytokines in tissue lysates of hearts, including tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), IL6 and monocyte chemoattractant protein-1 (MCP-1) were significantly elevated in CVA2 infected mice. Inflammatory signal pathways in heart tissues, including phosphatidylinositol 3-kinase (PI3K)-AKT, mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB), were also activated after infection. In summary, CVA2 infection leads to heart injury in a neonatal mouse model, which might be related to viral replication, increased expression levels of MMP-related enzymes and excessive inflammatory responses.

TLR3 polymorphisms are associated with the severity of hand, foot, and mouth disease caused by enterovirus A71 in a Chinese children population

Hand, foot, and mouth disease (HFMD) caused by enterovirus A71 (EV-A71) is a contagious viral disease, and toll-like receptors (TLRs) play essential roles in resisting the pathogen. The aim of this study was to assess the potential relationship between several TLRs polymorphisms and the HFMD severity in a Chinese children population. A total of 328 Chinese children with HFMD were included in the present study. The polymorphisms of TLR3 (rs3775290, rs3775291, rs3775296, rs1879026, rs5743312, rs5743313, rs5743303, rs13126816, and rs3775292), TLR4 (rs4986790, rs4986791, rs2149356, rs11536889, and rs41426344), TLR7 (rs179009, rs179010, rs179016, rs3853839, rs2302267, rs1634323, and rs5741880), and TLR8 (rs3764880, rs2159377, rs2407992, rs5744080, rs3747414, rs3764879, and rs5744069) genes were selected. The study indicated that individuals with the GG genotype of TLR3 single-nucleotide polymorphism rs1879026 had a higher risk of developing severe cases (GG vs. GT: OR = 1.875; 95% CI, 1.183-2.971; p = .007). Meanwhile, TLR3 rs3775290 CC genotype and C allele were associated with lower disease severity in females (CC vs. CT: OR = 0.350; 95% CI, 0.163-0.751; p = .006; C vs. T: OR = 0.566; 95% CI, 0.332-0.965; p = .036). TLR3 rs3775291 CC genotype showed 2.537 folds higher risk of developing severe cases in females (CC vs. CT: OR = 2.537; 95% CI, 1.108-5.806; p = .026). Moreover, TLR3 rs1879026 GG genotype was found to be related to increased risk of severe cases in males (GG vs. GT: OR = 2.076; 95% CI, 1.144-3.768; p = .016). The current findings show that the genetic variants of TLR3 rs1879026, rs3775290, and rs3775291 are associated with the severity of EV-A71-associated HFMD in a Chinese children population.

Epidemiological and molecular characteristics of circulating CVA16, CVA6 strains and genotype distribution in hand, foot and mouth disease cases in 2017 to 2018 from Western India

Hand, Foot, and Mouth disease (HFMD) is a mild exanthematous and febrile disease occurs in children aged ≤10 years old. The present study highlights clinical, epidemiological characteristics, distribution of enterovirus (EV) types, and sub genotypes in HFMD cases reported during 2017 to 2018 in Western India. A total of 93 clinical samples collected from 68 HFMD cases were included. The presence of EV-RNA was determined by 5'UTR based nested reverse transcription polymerase chain reaction followed by molecular typing, sub genotyping by VP1/2A junction or VP1, full VP1 gene amplification, and phylogenetic analysis. The study reports 80.64% (75/93) EV positivity and 94.66% (71/75) typing rate, with a predominant circulation of CVA16 and CVA6 strains. Sequence analysis revealed the presence of coxsackievirus (CV)A16 (57.7%), CVA6 (40.8%), and Echo1 (1.4%) strains. EV infections were predominantly observed in children aged 1 to 3 years old (43.9%). Although cases were reported throughout the year, peaked in July (15.8%) and August (24.6%) months and persisted till September (19.3%). All the CVA16 and CVA6 positive strains were genotyped using full VP1 gene amplification. All CVA16 Indian strains (n = 41) were clustered with rarely reported B1c sub genotype and CVA6 strains (n = 29) with E2 sub-lineage. The study highlights the genetic characteristics of circulating CVA16, CVA6, and Echo1 strains in HFMD cases from Western India. The emergence of CVA16 B1c genotype and sub-lineage E2 of CVA6 strains and their constant circulation further demands systemic surveillance studies on HFMD from different parts of India to facilitate the rapid diagnosis of CVA16 and CVA6 strains using the molecular and serological based approach and for intervention strategies.

How to improve infectious disease prediction by integrating environmental data: an application of a novel ensemble analysis strategy to predict HFMD

This study proposed a novel ensemble analysis strategy to improve hand, foot and mouth disease (HFMD) prediction by integrating environmental data. The approach began by establishing a vector autoregressive model (VAR). Then, a dynamic Bayesian networks (DBN) model was used for variable selection of environmental factors. Finally, a VAR model with constraints (CVAR) was established for predicting the incidence of HFMD in Chengdu city from 2011 to 2017. DBN showed that temperature was related to HFMD at lags 1 and 2. Humidity, wind speed, sunshine, PM₁₀, SO₂ and NO₂ were related to HFMD at lag 2. Compared with the autoregressive integrated moving average model with external variables (ARIMAX), the CVAR model had a higher coefficient of determination (R², average difference: + 2.11%; t = 6.2051, P = 0.0003 < 0.05), a lower root mean-squared error (−24.88%; t = −5.2898, P = 0.0007 < 0.05) and a lower mean absolute percentage error (−16.69%; t = −4.3647, P = 0.0024 < 0.05). The accuracy of predicting the time-series shape was 88.16% for the CVAR model and 86.41% for ARIMAX. The CVAR model performed better in terms of variable selection, model interpretation and prediction. Therefore, it could be used by health authorities to identify potential HFMD outbreaks and develop disease control measures.

Seasonality of the transmissibility of hand, foot and mouth disease: a modelling study in Xiamen City, China

This study attempts to figure out the seasonality of the transmissibility of hand, foot and mouth disease (HFMD). A mathematical model was established to calculate the transmissibility based on the reported data for HFMD in Xiamen City, China from 2014 to 2018. The transmissibility was measured by effective reproduction number (R_eff) in order to evaluate the seasonal characteristics of HFMD. A total of 43 659 HFMD cases were reported in Xiamen, for the period 2014 to 2018. The median of annual incidence was 221.87 per 100 000 persons (range: 167.98/100,000–283.34/100 000). The reported data had a great fitting effect with the model (R² = 0.9212, P < 0.0001), it has been shown that there are two epidemic peaks of HFMD in Xiamen every year. Both incidence and effective reproduction number had seasonal characteristics. The peak of incidence, 1–2 months later than the effective reproduction number, occurred in Summer and Autumn, that is, June and October each year. Both the incidence and transmissibility of HFMD have obvious seasonal characteristics, and two annual epidemic peaks as well. The peak of incidence is 1–2 months later than R_eff.

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.

Association of polymorphisms in the vitamin D receptor gene with severity of hand, foot, and mouth disease caused by enterovirus 71

Severe hand, foot, and mouth disease (HFMD) is sometimes associated with critical complications that can cause substantial child mortality. Activity of the vitamin D receptor (VDR) may influence the outcomes of enterovirus 71 (EV71) infection. This case-control study aimed to assess the association of single-nucleotide polymorphisms (SNPs) in the gene encoding the VDR with the severity of EV71-associated HFMD. We selected four VDR SNPs based on linkage disequilibrium and functional prediction, and we tested them using the SNPscan multiple SNP typing method for potential association with severity of EV71-associated HFMD. We found a significant association in the case of rs11574129 (G vs A: odds ratio (OR), 0.3439; 95% confidence intervals (CI), 0.1778-0.6653) and rs739837 (T vs G: OR, 0.5580; 95%CI, 0.3352-0.9291). Our results suggest that these two SNPs may influence the severity of EV71-associated HFMD.

The impact of hand, foot and mouth disease control policies in Singapore: A qualitative analysis of public perceptions

Hand foot and mouth disease (HFMD) is a widespread pediatric disease in Asia. Most cases are relatively mild and caused by Coxsackie viruses, but in epidemics caused by Enterovirus 71, severe complications can occur. In response to the deaths of dozens of children in a 1997 outbreak (Podin in BMC Public Health 6:180,1 Abubakar in Virus Res 61(1):1-9,2 WHO in3), Singapore practices childcare centre surveillance, case-isolation, and short-term closure of centres. We conducted 44 in-depth interviews with teachers, principals, and parents at four childcare centres in Singapore to better understand experiences with current control policies. We used applied thematic analysis to identify recurrent and unique themes. Participants were conflicted by perceiving HFMD as a severe illness and reported a sense of helplessness when hygiene and social-isolation efforts failed. They perceived that severity of HFMD influenced Singapore's choice of existing policies despite a lack of evidence of their effectiveness. Documenting stakeholders' perspectives clarifies the impact of control measures and how to communicate policy changes.

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.

肠道病毒71型感染手足口病S100B基因多态性研究

OBJECTIVE

To investigate the association between rs9722 polymorphisms in the S100B gene and hand, foot and mouth disease (HFMD) caused by enterovirus 71.

METHODS

A total of 124 HFMD children with enterovirus 71 infection were enrolled as subjects, and 56 healthy children were enrolled as control group. The rs9722 polymorphisms in the S100B gene were detected for both groups, and the serum level of S100B protein was measured for 74 HFMD children.

RESULTS

The rs9722 locus of the S100B gene had three genotypes, CC, CT, and TT, and the genotype frequencies were in accordance with Hardy-Weinberg equilibrium. Compared with the control group, the HFMD group had significant increases in the frequencies of TT genotype and T allele (P<0.01). Children with severe HFMD caused by enterovirus 71 infection had significantly higher frequencies of TT genotype and T allele than those with moderate or mild HFMD (P<0.05). Compared with the cured patients, the patients with poor prognosis had significant increases in the frequencies of TT genotype and T allele in the rs9722 locus of the S100B gene (P<0.05). Among the 74 children with HFMD, the children with TT genotype had the highest serum level of S100B protein, and those with CC genotype had the lowest level (P<0.01).

CONCLUSIONS

T allele in the rs9722 locus of the S100B gene might be a risk factor for severe HFMD caused by enterovirus 71 infection.

[Association between S100B gene polymorphisms and hand, foot and mouth disease caused by enterovirus 71 infection]

OBJECTIVE

To investigate the association between rs9722 polymorphisms in the S100B gene and hand, foot and mouth disease (HFMD) caused by enterovirus 71.

METHODS

A total of 124 HFMD children with enterovirus 71 infection were enrolled as subjects, and 56 healthy children were enrolled as control group. The rs9722 polymorphisms in the S100B gene were detected for both groups, and the serum level of S100B protein was measured for 74 HFMD children.

RESULTS

The rs9722 locus of the S100B gene had three genotypes, CC, CT, and TT, and the genotype frequencies were in accordance with Hardy-Weinberg equilibrium. Compared with the control group, the HFMD group had significant increases in the frequencies of TT genotype and T allele (P<0.01). Children with severe HFMD caused by enterovirus 71 infection had significantly higher frequencies of TT genotype and T allele than those with moderate or mild HFMD (P<0.05). Compared with the cured patients, the patients with poor prognosis had significant increases in the frequencies of TT genotype and T allele in the rs9722 locus of the S100B gene (P<0.05). Among the 74 children with HFMD, the children with TT genotype had the highest serum level of S100B protein, and those with CC genotype had the lowest level (P<0.01).

CONCLUSIONS

T allele in the rs9722 locus of the S100B gene might be a risk factor for severe HFMD caused by enterovirus 71 infection.

[Myocardial protective effect of L-carnitine in children with hand, foot and mouth disease caused by Coxsackie A16 virus]

OBJECTIVE

To investigate the myocardial protective effect of L-carnitine in children with hand, foot and mouth disease (HFMD) caused by Coxsackie A16 virus and possible mechanisms.

METHODS

A total of 60 HFMD children with abnormal myocardial enzyme after Coxsackie A16 virus infection were enrolled and randomly divided into L-carnitine group and fructose-1,6-diphosphate group (fructose group), with 30 children in each group. The two groups were given L-carnitine or fructose diphosphate in addition to antiviral and heat clearance treatment. Another 30 healthy children who underwent physical examination were enrolled as control group. The changes in myocardial zymogram, malondialdehyde (MDA), superoxide dismutase (SOD), and apoptosis factors sFas and sFasL after treatment were compared between groups.

RESULTS

There was no significant difference in treatment response between the L-carnitine group and the fructose group (P>0.05). One child in the fructose group progressed to critical HFMD, which was not observed in the L-carnitine group. Before treatment, the L-carnitine group and the fructose group had significantly higher indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significantly lower level of SOD than the control group (P<0.05), while there were no significant differences in these indices between the L-carnitine group and the fructose group (P>0.05). After treatment, the L-carnitine group and the fructose group had significant reductions in the indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significant increase in the level of SOD (P<0.05); the fructose group had a significantly higher level of creatine kinase (CK) than the control group and the L-carnitine group, and there were no significant differences in other myocardial enzyme indices, MDA, sFas, and sFasL between the L-carnitine group and the fructose group, as well as between the L-carnitine and fructose groups and the control group (P>0.05). SOD level was negatively correlated with aspartate aminotransferase, lactate dehydrogenase (LDH), CK, and creatine kinase-MB (CK-MB) (r=-0.437, -0.364, -0.397, and -0.519 respectively; P<0.05), and MDA level was positively correlated with LDH and CK-MB (r=0.382 and 0.411 respectively; P<0.05).

CONCLUSIONS

L-carnitine exerts a good myocardial protective effect in children with HFMD caused by Coxsackie A16 virus, possibly by clearing oxygen radicals and inhibiting cardiomyocyte apoptosis.

[Myocardial protective effect of L-carnitine in children with hand, foot and mouth disease caused by Coxsackie A16 virus]

OBJECTIVE

To investigate the myocardial protective effect of L-carnitine in children with hand, foot and mouth disease (HFMD) caused by Coxsackie A16 virus and possible mechanisms.

METHODS

A total of 60 HFMD children with abnormal myocardial enzyme after Coxsackie A16 virus infection were enrolled and randomly divided into L-carnitine group and fructose-1,6-diphosphate group (fructose group), with 30 children in each group. The two groups were given L-carnitine or fructose diphosphate in addition to antiviral and heat clearance treatment. Another 30 healthy children who underwent physical examination were enrolled as control group. The changes in myocardial zymogram, malondialdehyde (MDA), superoxide dismutase (SOD), and apoptosis factors sFas and sFasL after treatment were compared between groups.

RESULTS

There was no significant difference in treatment response between the L-carnitine group and the fructose group (P>0.05). One child in the fructose group progressed to critical HFMD, which was not observed in the L-carnitine group. Before treatment, the L-carnitine group and the fructose group had significantly higher indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significantly lower level of SOD than the control group (P<0.05), while there were no significant differences in these indices between the L-carnitine group and the fructose group (P>0.05). After treatment, the L-carnitine group and the fructose group had significant reductions in the indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significant increase in the level of SOD (P<0.05); the fructose group had a significantly higher level of creatine kinase (CK) than the control group and the L-carnitine group, and there were no significant differences in other myocardial enzyme indices, MDA, sFas, and sFasL between the L-carnitine group and the fructose group, as well as between the L-carnitine and fructose groups and the control group (P>0.05). SOD level was negatively correlated with aspartate aminotransferase, lactate dehydrogenase (LDH), CK, and creatine kinase-MB (CK-MB) (r=-0.437, -0.364, -0.397, and -0.519 respectively; P<0.05), and MDA level was positively correlated with LDH and CK-MB (r=0.382 and 0.411 respectively; P<0.05).

CONCLUSIONS

L-carnitine exerts a good myocardial protective effect in children with HFMD caused by Coxsackie A16 virus, possibly by clearing oxygen radicals and inhibiting cardiomyocyte apoptosis.

Spatio-Temporal Pattern and Risk Factor Analysis of Hand, Foot and Mouth Disease Associated with Under-Five Morbidity in the Beijing-Tianjin-Hebei Region of China

Hand, foot and mouth disease (HFMD) in children under the age of five is a major public health issue in China. Beijing–Tianjin–Hebei is the largest urban agglomeration in northern China. The present study aimed to analyze the epidemiological features of HFMD, reveal spatial clusters, and detect risk factors in this region. Reports of HFMD cases in Beijing–Tianjin–Hebei from 1 January 2013 to 31 December 2013 were collected from 211 counties or municipal districts. First, the epidemiological features were explored, and then SaTScan analysis was carried out to detect spatial clusters of HFMD. Finally, GeoDetector and spatial paneled model were used to identify potential risk factors among the socioeconomic and meteorological variables. There were a total of 90,527 HFMD cases in the year 2013. The highest rate was in individuals aged one year, with an incidence of 24.76/10³. Boys (55,168) outnumbered girls (35,359). Temporally, the incidence rose rapidly from April, peaking in June (4.08/10³). Temperature, relative humidity and wind speed were positively associated with the incidence rate, while precipitation and sunshine hours had a negative association. The explanatory powers of these factors were 57%, 13%, 2%, 21% and 12%, respectively. Spatially, the highest-risk regions were located in Beijing and neighboring areas, with a relative risk (RR) value of 3.04. The proportion of primary industry was negatively associated with HFMD transmission, with an explanatory power of 32%. Gross domestic product (GDP) per capita, proportion of tertiary industry, and population density were positively associated with disease incidence, with explanatory powers of 22%, 17% and 15%, respectively. These findings may be helpful in the risk assessment of HFMD transmission and for implementing effective interventions to reduce the burden of this disease.

[Value of serum S100B protein and neuron-specific enolase levels in predicting the severity of hand, foot and mouth disease]

OBJECTIVE

To study the value of serum S100B protein and neuron-specific enolase (NSE) levels in predicting the severity of hand, foot and mouth disease (HFMD).

METHODS

Ninety children with HFMD were classified into three groups: common type, severe type, and critical type (n=30 each). Thirty healthy children were randomly selected as the control group. ELISA was used to measure serum levels of S100B protein and NSE before and at 7 days after treatment. The receiver operating characteristic (ROC) curve was used to evaluate the prediction efficiency of S100B protein and NSE for the severity of HFMD.

RESULTS

The critical type group had significant increases in the serum levels of S100B protein and NSE compared with the other three groups (P<0.01). The severe type group had significant increases in serum levels of S100B protein and NSE compared with the common type and control groups (P<0.01). The critical type and severe type groups had significant reductions in serum levels of S100B protein and NSE after treatment (P<0.05). Serum S100B protein had the highest Youden value of 0.611 at the cut-off value of 0.445 μg/L, with a sensitivity of 61% and a specificity of 100%, in the prediction of serious HFMD (including severe type and critical type HFMD). Serum NSE had the highest Youden value of 0.533 at the cut-off value of 5.905 μg/L, with a sensitivity of 80% and a specificity of 73%, in the prediction of serious HFMD. Combined measurements of these two parameters had a sensitivity of 86% and a specificity of 73% and had the highest predictive value for serious HFMD.

CONCLUSIONS

The serum levels of S100B protein and NSE help to predict the severity and treatment outcomes of HFMD. Combined measurements of these two parameters has a higher predictive value for serious HFMD.

[Value of serum S100B protein and neuron-specific enolase levels in predicting the severity of hand, foot and mouth disease]

OBJECTIVE

To study the value of serum S100B protein and neuron-specific enolase (NSE) levels in predicting the severity of hand, foot and mouth disease (HFMD).

METHODS

Ninety children with HFMD were classified into three groups: common type, severe type, and critical type (n=30 each). Thirty healthy children were randomly selected as the control group. ELISA was used to measure serum levels of S100B protein and NSE before and at 7 days after treatment. The receiver operating characteristic (ROC) curve was used to evaluate the prediction efficiency of S100B protein and NSE for the severity of HFMD.

RESULTS

The critical type group had significant increases in the serum levels of S100B protein and NSE compared with the other three groups (P<0.01). The severe type group had significant increases in serum levels of S100B protein and NSE compared with the common type and control groups (P<0.01). The critical type and severe type groups had significant reductions in serum levels of S100B protein and NSE after treatment (P<0.05). Serum S100B protein had the highest Youden value of 0.611 at the cut-off value of 0.445 μg/L, with a sensitivity of 61% and a specificity of 100%, in the prediction of serious HFMD (including severe type and critical type HFMD). Serum NSE had the highest Youden value of 0.533 at the cut-off value of 5.905 μg/L, with a sensitivity of 80% and a specificity of 73%, in the prediction of serious HFMD. Combined measurements of these two parameters had a sensitivity of 86% and a specificity of 73% and had the highest predictive value for serious HFMD.

CONCLUSIONS

The serum levels of S100B protein and NSE help to predict the severity and treatment outcomes of HFMD. Combined measurements of these two parameters has a higher predictive value for serious HFMD.

[Expression of vasoactive intestinal peptide in peripheral blood of children with hand, foot and mouth disease]

OBJECTIVE

To investigate the expression of vasoactive intestinal peptide (VIP) in peripheral blood of children with hand, foot and mouth disease and its significance.

METHODS

According to the condition of the disease, 86 children with hand, foot and mouth disease were classified into phase 1 group (19 children) and phase 2 group (67 children). ELISA was used to measure the concentrations of plasma VIP, interferon-γ (IFN-γ), and interleukin-4 (IL-4) in peripheral blood. Flow cytometry was used to measure CD3⁺, CD4⁺, and CD8⁺ T lymphocyte subsets. RT-PCR was used for qualitative detection of enterovirus 71 (EV71) RNA in stool.

RESULTS

Compared with the phase 1 group, the phase 2 group had a significantly higher positive rate of EV71-RNA (P<0.05) and significantly higher serum levels of IgG, IgA, IgM, and C3 (P<0.05). The phase 2 group had significantly lower proportions of peripheral CD3⁺, CD4⁺, and CD8⁺ T lymphocyte subsets than the phase 1 group (P<0.05), as well as significantly lower proportion of peripheral B cells and CD4⁺/CD8⁺ ratio than the phase 1 group (P<0.05). The phase 2 group also had a significantly lower concentration of VIP in peripheral blood than the phase 1 group (P<0.05). In the 86 children with hand, foot and mouth disease, the concentration of VIP in peripheral blood was positively correlated with the proportion of CD4⁺ T lymphocyte subset and CD4⁺/CD8⁺ ratio (r=0.533 and 0.532 respectively; P<0.05).

CONCLUSIONS

VIP may be an important marker of the severity of hand, foot and mouth disease.

Optimize the interactions at S4 with efficient inhibitors targeting 3C proteinase from enterovirus 71

Enterovirus 71 (EV71) is the causative agent of hand, foot and mouth disease and can spread its infections to the central nervous and other systems with severe consequences. The replication of EV71 depends on its 3C proteinase (3Cpro ), a significant drug target. By X-ray crystallography and functional assays, the interactions between inhibitors and EV71 3Cpro were evaluated. It was shown that improved interactions at S4 for the substrate binding could significantly enhance the potency. A new series of potent inhibitors with high ligand efficiency was generated for developing antivirals to treat and control the EV71-associated diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Atypical hand, foot and mouth disease in adults associated with coxsackievirus A6: a clinico-pathologic study

BACKGROUND

Hand, foot, and mouth disease (HFMD) is a contagious illness most commonly occurring in children 5 years old or younger. The most common cause of HFMD in the United States is Coxsackievirus A16. HFMD is uncommon in adults, and may show other atypical features including a broader spectrum of cutaneous involvement and a greater degree of severity.

METHODS

We evaluated the clinical, histopathologic and molecular features of three cases of atypical HFMD occurring in adults.

RESULTS

All three cases showed clinical features that were worrisome for erythema multiforme or a disseminated herpesvirus infection. The histopathologic findings were quite uniform, and showed intraepidermal vesiculation with a predominantly neutrophil-rich infiltrate. A characteristic feature was the specific involvement of the upper stratum spinosum and stratum granulosum, with relative sparing of the stratum corneum. In none of the cases was there evidence of herpesvirus. Molecular analysis performed on two of the cases showed involvement by Coxsackievirus A6, an uncommon serotype in HFMD. All three cases resolved spontaneously.

CONCLUSIONS

Atypical HFMD associated with Coxsackievirus A6 represents an uncommon and potentially diagnostically challenging cutaneous eruption. Its recognition is critical to avoid unneeded therapy and to establish accurate prognostic expectations.

Disease burden of enterovirus 71 in rural central China: A community-based survey

In recent years, the epidemics of hand, foot, and mouth disease (HFMD) centered in the Asian-Pacific region have been characterized by high morbidity and mortality. Enterovirus 71 (EV71) infections were responsible for the majority of the infections leading to severe cases of HFMD and death. This is a community-based survey aimed to estimate the disease burden of EV71 in rural central China, especially for HFMD. From 2011 to 2013, demographic and socio-economic data were gathered from 343 ill children and their parents using a structured questionnaire. We quantified the health burden of disease resulting from EV71 infection in disability-adjusted life years (DALYs). Among 343 cases, 303 had confirmed HFMD, 6 presented with herpangina, 25 presented with respiratory symptoms, and 9 presented with non-specific symptoms. The number of severe cases was 47 (including 1 death) and all of these presented with HFMD. The total cost per patient for severe HFMD, mild HFMD, herpangina, respiratory disease, and non-specific disease was $2149.47, $513.22, $53.28, $31.95, and $39.25, respectively. The overall cost of EV71-related diseases as a proportion of local farmers' per capita net income ranged from 0.18% for those with non-specific disease to 187.12% for those with severe HFMD. The loss of DALYs for the 5 forms of disease were 3.47, 1.76, 1.07, 1.44, 1.22 person-years per 1000 persons, respectively. This study provides data on cost of treatment and health burden for diseases caused by EV71, which can be used in the evaluation of EV71 vaccine cost-effectiveness.

Hand-Washing: The Main Strategy for Avoiding Hand, Foot and Mouth Disease

Epidemics of hand, foot and mouth disease (HFMD) among children have caused concern in China since 2007. We have conducted a retrospective study to investigate risk factors associated with HFMD. In this non-matching case-control study, 99 HFMD patients and 126 control from Guangdong Province were enlisted as participants. Data comprising demographic, socio-economic, clinical and behavior factors were collected from children's parents through face-to-face interviews by trained interviewers using a standardized questionnaire. Results of the primary logistic regression analyses revealed that age, history of cold food consumption, hand-washing routines, and airing out bedding were significantly associated with HFMD cases. Results of further multivariate analysis indicated that older age (OR = 0.44, 95% CI: 0.34-0.56) and hand-washing before meals (OR = 0.3, 95% CI: 0.13-0.70) are protective factors, whereas airing out bedding more than thrice a month (OR = 4.55, 95% CI: 1.19-17.37) was associated with increased risk for HFMD. Therefore, hand-washing should be recommended to prevent HFMD, and the potential threat of airing out bedding should be carefully considered. However, further studies are needed to examine other possible risk factors.

[Limb torsion and developmental regression for one month after hand, foot and mouth disease in an infant]

A one-year-old girl visited the hospital due to limb torsion and developmental regression for one month after hand, foot and mouth disease. At the age of 11 months, she visited a local hospital due to fever for 5 days and skin rash with frequent convulsions for 2 days and was diagnosed with severe hand, foot and mouth disease, viral encephalitis, and status epilepticus. Brain MRI revealed symmetric abnormal signals in the bilateral basal ganglia, bilateral thalamus, cerebral peduncle, bilateral cortex, and hippocampus. She was given immunoglobulin, antiviral drugs, and anticonvulsant drugs for 2 weeks, and the effect was poor. Blood and urine screening for inherited metabolic diseases were performed to clarify the etiology. The analysis of urine organic acids showed significant increases in glutaric acid and 3-hydroxyglutaric acid, which suggested glutaric aciduria type 1, but her blood glutarylcarnitine was normal, and free carnitine significantly decreased. After the treatment with low-lysine diets, L-carnitine, and baclofen for 1 month, the patient showed a significant improvement in symptoms. Hand, foot and mouth disease is a common viral infectious disease in children, and children with underlying diseases such as inherited metabolic diseases and immunodeficiency may experience serious complications. For children with hand, foot and mouth disease and unexplained encephalopathy, inherited metabolic diseases should be considered.

[Limb torsion and developmental regression for one month after hand, foot and mouth disease in an infant]

A one-year-old girl visited the hospital due to limb torsion and developmental regression for one month after hand, foot and mouth disease. At the age of 11 months, she visited a local hospital due to fever for 5 days and skin rash with frequent convulsions for 2 days and was diagnosed with severe hand, foot and mouth disease, viral encephalitis, and status epilepticus. Brain MRI revealed symmetric abnormal signals in the bilateral basal ganglia, bilateral thalamus, cerebral peduncle, bilateral cortex, and hippocampus. She was given immunoglobulin, antiviral drugs, and anticonvulsant drugs for 2 weeks, and the effect was poor. Blood and urine screening for inherited metabolic diseases were performed to clarify the etiology. The analysis of urine organic acids showed significant increases in glutaric acid and 3-hydroxyglutaric acid, which suggested glutaric aciduria type 1, but her blood glutarylcarnitine was normal, and free carnitine significantly decreased. After the treatment with low-lysine diets, L-carnitine, and baclofen for 1 month, the patient showed a significant improvement in symptoms. Hand, foot and mouth disease is a common viral infectious disease in children, and children with underlying diseases such as inherited metabolic diseases and immunodeficiency may experience serious complications. For children with hand, foot and mouth disease and unexplained encephalopathy, inherited metabolic diseases should be considered.

[Effect of continuous hemofiltration on inflammatory mediators and hemodynamics in children with severe hand, foot and mouth disease]

OBJECTIVE

To investigate the effect of continuous veno-venous hemofiltration (CVVH) on inflammatory mediators in children with severe hand, foot and mouth disease (HFMD), and to investigate its clinical efficacy.

METHODS

A total of 36 children with stage IV HFMD were enrolled and randomly divided into conventional treatment group and CVVH group (n=18 each). The children in the CVVH group were given CVVH for 48 hours in addition to the conventional treatment. The levels of interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and lactic acid in peripheral venous blood, heart rate, blood pressure, and left ventricular ejection fraction were measured before treatment and after 24 and 48 hours of treatment.

RESULTS

After 24 hours of treatment, the conventional treatment group had a significantly reduced serum IL-2 level (P<0.01), and the CVVH treatment group had significantly reduced serum levels of IL-2, IL-6, IL-10, and TNF-α (P<0.05). After 48 hours of treatment, both groups had significantly reduced serum levels of IL-2, IL-6, IL-10, and TNF-α (P<0.01), and the CVVH group had significantly lower levels of these inflammatory factors than the conventional treatment group (P<0.01). After 48 hours of treatment, heart rate, systolic pressure, and blood lactic acid level were significantly reduced, and left ventricular ejection fraction was significantly increased in both groups, and the CVVH group had significantly greater changes in these indices except systolic pressure than the conventional treatment group (P<0.01).

CONCLUSIONS

CVVH can effectively eliminate inflammatory factors, reduce heart rate and venous blood lactic acid, and improve heart function in children with severe HFMD.

Phylogenetic analysis of the major causative agents of hand, foot and mouth disease in Suzhou City, Jiangsu province, China, in 2012-2013

Hand, foot and mouth disease (HFMD) is a serious public health problem that has emerged over the past several decades. Pathogen detection by the Chinese national HFMD surveillance system has focused mainly on enterovirus 71 (EV71) and coxsackievirus A16 (CA16). Therefore, epidemiological information regarding the other causative enteroviruses is limited. To identify the pandemic enterovirus in Suzhou, Jiangsu province, China, clinical samples from patients with HFMD were collected from 2012 to 2013 and analyzed. The results revealed that CA16 was the most dominant HFMD pathogen in 2012, whereas CA6 and CA10 were the dominant pathogens in 2013. Phylogenetic analysis revealed that the C4a sub-genogroup of EV71 and the B1a and B1b sub-genogroups of CA16 continued to evolve and circulate in Suzhou. The CA6 strains were assigned to six genotypes (A–F) and the CA10 strains were assigned to seven genotypes (A–G), with clear geographical and temporal distributions. All of the CA6 strains in Suzhou belonged to genogroup F, and there were several lineages circulating in Suzhou. All of the CA10 strains in Suzhou belonged to genogroup G, and they had the same genetic origin. Co-infections of EV71/CA16 and CA6/CA10 were found in the samples, and bootscan analysis of 5′-untranslated regions (UTRs) revealed that some CA16 strains in Suzhou had genetic recombination with EV71. This property might allow CA16 to alter its evolvability and circulating ability. This study underscores the need for surveillance of CA6 and CA10 in the Yangtze River Delta and East China.

Protective effect of exclusive breastfeeding against hand, foot and mouth disease

BACKGROUND

Infants who are exclusively breastfed receive natural protection against some infectious agents. This study examined whether there was protective effect of exclusive breastfeeding on the occurrence of hand, foot and mouth disease, which was an emerging infectious disease among children in China.

METHODS

A community-based case-control study was carried out among children age 4 years or younger in Guangdong Province, China. Cases were newly diagnosed hand, foot and mouth disease. Controls were randomly sampled from healthy children from the nearby village. Unconditional logistic regression model was used to estimate the odds ratio (OR) for exclusive breastfeeding after adjusting for potential confounding factors.

RESULTS

A total of 316 cases and 566 controls were included in the analysis. Significantly beneficial effect of exclusive breastfeeding during the first 6 months was observed for hand, foot and mouth disease occurrence. The overall OR was 0.63 (95% CI: 0.47-0.85) for exclusive breastfeeding compared with mixed feeding type. The age-specific analyses indicated that the protective effect persisted till the age of 28 months.

CONCLUSIONS

This study suggests that exclusive breastfeeding might have protective effect against HFMD infection among the children within 28 months of age.

Review of enterovirus 71 vaccines

Enterovirus 71 (EV71) and coxsackieviruses are the major causative agents of hand, foot, and mouth disease (HFMD) outbreaks worldwide and have a significant socioeconomic impact, particularly in Asia. Formalin-inactivated (FI) EV71 vaccines evaluated in human clinical trials in China, Taiwan, and Singapore were found to be safe and to elicit strong neutralizing antibody responses against EV71 currently circulating in Asia. The results from 3 different phase 3 clinical trials performed in young children (6-60 months) indicate that the efficacy of FI-EV71 vaccines is >90% against EV71-related HFMDs and >80% against EV71-associated serious diseases, but the vaccines did not protect against coxsackievirus A16 infections. Here we discuss the critical factors affecting EV71 vaccine product registration, including clinical epidemiology, antigenic shift issues in cross-protection and vaccine strain selection, standardized animal models for potency testing, and cost-effective manufacturing processes for potential incorporation of FI-EV71 vaccine into Expanded Programme on Immunization vaccines.

First isolation and genomic characterization of enterovirus A71 and coxsackievirus A16 from hand foot and mouth disease patients in the Lao PDR

Enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are major aetiological agents of hand, foot and mouth disease in Asia. We established the first genomic characterization of strains isolated in 2011 from Lao patients. Isolates were related to EV-A71 genotype C4 and CV-A16 genotype B1a that circulated in neighbouring countries during the same period. This confirms the regional character of hand, foot and mouth disease epidemiology and makes plausible the occurrence of severe disease in the Lao population.

The approved pediatric drug suramin identified as a clinical candidate for the treatment of EV71 infection-suramin inhibits EV71 infection in vitro and in vivo

Enterovirus 71 (EV71) causes severe central nervous system infections, leading to cardiopulmonary complications and death in young children. There is an urgent unmet medical need for new pharmaceutical agents to control EV71 infections. Using a multidisciplinary approach, we found that the approved pediatric antiparasitic drug suramin blocked EV71 infectivity by a novel mechanism of action that involves binding of the naphtalentrisulonic acid group of suramin to the viral capsid. Moreover, we demonstrate that when suramin is used in vivo at doses equivalent to or lower than the highest dose already used in humans, it significantly decreased mortality in mice challenged with a lethal dose of EV71 and peak viral load in adult rhesus monkeys. Thus, suramin inhibits EV71 infection by neutralizing virus particles prior to cell attachment. Consequently, these findings identify suramin as a clinical candidate for further development as a therapeutic or prophylactic treatment for severe EV71 infection.

The effect of meteorological factors on adolescent hand, foot, and mouth disease and associated effect modifiers

Background

Hand, foot, and mouth disease (HFMD) is a contagious viral illness that commonly affects infants and children. This infection is an emerging infectious disease in Rizhao in recent years. The present study examined the short-term effects of meteorological factors on adolescent HFMD in Rizhao.

Design

A generalized additive Poisson model was applied to estimate the effects of meteorological factors on adolescent HFMD occurrence in 2010–2012. Subgroup analyses were also conducted to examine the potential effect modifiers of the association in terms of age, sex, and occupation.

Results

A positive effect of temperature was observed (ER [excess risk]=1.93%, 95% CI: 1.05 to 2.82% for 1°C increase on lag 5 day). A negative effect of relative humidity at lag 1 day and positive effects were found on lag 5–7 days, and an adverse effect was observed for sunshine at lag days 3–4 (ER=−0.71%, 95% CI: −1.25 to −0.17% on lag day 4). We also found that age, sex, and occupation might be important effect modifiers of the effects of weather variables on HFMD.

Conclusions

This study suggests that meteorological factors might be an important predictor of adolescent HFMD occurrence in Rizhao. Age, sex, and occupation might be important effect modifiers of the effects.

Receptors for enterovirus 71

Enterovirus 71 (EV71) is one of the major causative agents of hand, foot and mouth disease (HFMD). Occasionally, EV71 infection is associated with severe neurological diseases, such as acute encephalitis, acute flaccid paralysis and cardiopulmonary failure. Several molecules act as cell surface receptors that stimulate EV71 infection, including scavenger receptor B2 (SCARB2), P-selectin glycoprotein ligand-1 (PSGL-1), sialylated glycan, heparan sulfate and annexin II (Anx2). SCARB2 plays critical roles in attachment, viral entry and uncoating, and it can facilitate efficient EV71 infection. The three-dimensional structures of the mature EV71 virion, procapsid and empty capsid, as well as the exofacial domain of SCARB2, have been elucidated. This structural information has greatly increased our understanding of the early steps of EV71 infection. Furthermore, SCARB2 plays essential roles in the development of EV71 neurological disease in vivo. Adult mice are not susceptible to infection by EV71, but transgenic mice that express human SCARB2 become susceptible to EV71 infection and develop similar neurological diseases to those found in humans. This mouse model facilitates the in vivo investigation of many issues related to EV71. PSGL-1, sialylated glycan, heparan sulfate and Anx2 are attachment receptors, which enhance viral infection by retaining the virus on the cell surface. These molecules also contribute to viral infection in vitro either by interacting with SCARB2 or independently of SCARB2. However, the cooperative effects of these receptors, and their contribution to EV71 pathogenicity in vivo, remain to be elucidated.

Neutralizing antibody responses to enterovirus and adenovirus in healthy adults in China

Hand, foot and mouth disease (HFMD) is an important public health problem that has emerged over the past several years. HFMD predominantly infects children under seven years old and occasionally causes severe disease in adults. Among the enteroviruses, enterovirus 71 (EV71) and coxsackievirus 16 (CA16) are the major causative agents of HFMD. In addition, adenovirus cocirculates with enterovirus and has become a possible additional pathogenic factor for HFMD in some cases. Here, we have investigated the neutralizing antibody responses to both enterovirus and adenovirus in adults, with the aim of exploring the prevalence trends of these viruses and the nature of protective immunity in humans to these viral infections. Sera from 391 healthy adults from 21 provinces and cities in China were tested for the presence of antibodies against EV71, CA16, adenovirus human serotype 5 (AdHu5) and chimpanzee adenovirus pan7 (AdC7) using neutralization tests. High seroprevalence rates of EV71, CA16 and AdHu5 were found in the population (85.7%, 58.8% and 74.2%, respectively). The coseropositivity rate of these three viruses was 39.4% (154 of 391), with median neutralizing antibody titers of 80, 40 and 640, respectively, and the neutralizing antibody titer for EV71 was found to be correlated with those of CA16 and AdHu5. AdC7 was found to be a rare adenovirus serotype in the human population, with a seropositivity rate of 11.8%, suggesting that it could be a good choice for a vaccine carrier that could be used in vaccine development.

Children of rural-to-urban migrant workers in China are at a higher risk of contracting severe hand, foot and mouth disease and EV71 infection: a hospital-based study

The incidence and severity of hand, foot and mouth disease have increased in mainland China since 2008. Therapies and vaccines are currently at different stages of development. This study aimed to determine the social factors associated with the outbreaks and severity of the disease in Chinese children. A multicentre, prospective, case-controlled study was conducted in Shanghai, Chongqing, Guangzhou and Shantou to identify the sociodemographic and behavioural risk factors for hand, foot and mouth disease. Children hospitalized for hand, foot and mouth disease were randomly enrolled from April to November 2011. Stool samples were collected to test for the presence of enterovirus 71 (EV71). A total of 443 children between 1.6 and 68 months of age were enrolled; 304 were uncomplicated cases and 139 were severe cases with central nervous system involvement. The overall detection rate of EV71 was 54.2%, and the positivity rate of EV71 was significantly higher in the severe group than in the uncomplicated group (82.0% versus 40.9%, odds ratio (OR): 8.35, P=0.000). The children of migrant workers (OR: 3.014, P=0.000) and children attending kindergarten (OR: 2.133, P=0.002) were significantly associated with a severe outcome of the disease (OR: 1.765, P=0.026). Our findings indicate that kindergarten attendance and migrant worker parents are the major risk factors associated with severe hand, foot and mouth disease in children <5 years of age. Future public health intervention vaccination campaigns should consider the particular difficulties of achieving high compliance with multiple-dose vaccination regimens in the children of migrant workers.

Human enterovirus 71 epidemics: what's next?

Human enterovirus 71 (EV71) epidemics have affected various countries in the past 40 years. EV71 commonly causes hand, foot and mouth disease (HFMD) in children, but can result in neurological and cardiorespiratory complications in severe cases. Genotypic changes of EV71 have been observed in different places over time, with the emergence of novel genotypes or subgenotypes giving rise to serious outbreaks. Since the late 1990s, intra- and inter-typic recombination events in EV71 have been increasingly reported in the Asia-Pacific region. In particular, 'double-recombinant' EV71 strains belonging to a novel genotype D have been predominant in mainland China and Hong Kong over the last decade, though co-circulating with a minority of other EV71 subgenotypes and coxsackie A viruses. Continuous surveillance and genome studies are important to detect potential novel mutants or recombinants in the near future. Rapid and sensitive molecular detection of EV71 is of paramount importance in anticipating and combating EV71 outbreaks.

Structures of Enterovirus 71 3C proteinase (strain E2004104-TW-CDC) and its complex with rupintrivir

The crystal structure of 3C proteinase (3C(pro)) from Enterovirus 71 (EV71) was determined in space group C2221 to 2.2 Å resolution. The fold was similar to that of 3C(pro) from other picornaviruses, but the difference in the β-ribbon reported in a previous structure was not observed. This β-ribbon was folded over the substrate-binding cleft and constituted part of the essential binding sites for interaction with the substrate. The structure of its complex with rupintrivir (AG7088), a peptidomimetic inhibitor, was also characterized in space group P212121 to 1.96 Å resolution. The inhibitor was accommodated without any spatial hindrance despite the more constricted binding site; this was confirmed by functional assays, in which the inhibitor showed comparable potency towards EV71 3C(pro) and human rhinovirus 3C(pro), which is the target that rupintrivir was designed against.