The surveillance of the epidemiological and serotype characteristics of hand, foot, mouth disease in Neijiang city, China, 2010-2017: A retrospective study

Long-term sentinel surveillance of enteroviruses in Gwangju, South Korea, 2011-2020

Human enteroviruses (EVs) are associated with a broad spectrum of diseases. To understand EV epidemiology, we present longitudinal data reflecting changing EV prevalence patterns in South Korea. We collected 7160 specimens from patients with suspected EV infections in ten hospitals in Gwangju, Korea during 2011-2020. RNA extraction and real-time reverse transcription polymerase chain reaction using EV-specific probes and primers were performed. EV genotyping and phylogenetic analysis were performed; EVs were detected in 3076 samples (43.0%), and the annual EV detection rate varied. EV infection rates did not differ with sex, and children aged ≤ 4 years were the most prone to EV infection; this trend did not change over time. Overall, 35 different EV types belonging to four distinctive species and rhinoviruses were identified. Although serotype distribution changed annually, the most frequently observed EVs were EV-A71 (13.1% of the cases), CVA6 (8.3%), CVB5 (7.6%), CVA16 (7.6%), CVA10 (7.5%), E18 (7.5%), E30 (7.0%), and E11 (5.0%) during 2011-2020. The predominant EV genotypes by clinical manifestation were CVB5 for aseptic meningitis; EV-A71 for hand, foot, and mouth disease cases; and CVA10 for herpangina. These results will aid the development of vaccines against EV infection and allow comprehensive disease control.

Seroprevalence of coxsackievirus A6 and enterovirus A71 infection in humans: a systematic review and meta-analysis

Hand, foot, and mouth disease (HFMD) is a common infectious disease in children. Enterovirus A71 (EV-A71) is one of the main pathogens, and coxsackievirus A6 (CVA6) has gradually become the dominant pathogen of HFMD in recent years. This study was conducted mainly to assess the serological prevalence of EV-A71 and CVA6 antibodies in people of different ages, sexes, and regions through a systematic review and meta-analysis. A comprehensive study was performed based on the EV-A71 and CVA6 serological literature published before May 2022. Heterogeneity analysis (Cochrane's Q test and the I2 statistic) and random effect models were adopted. Subgroup and meta-regression analyses were used to identify potential sources of heterogeneity in the data, and all analysis was performed using STATA version 16.0. This study included 71 studies involving 55,176 people from 13 countries that met the inclusion criteria. The serological prevalence of EV-A71 antibody in different studies was 4.31-88.8%, and that of CVA6 antibody was 40.8-80.9%. Meta-analysis results showed that the serum positive rate for EV-A71 antibody was 45.9% (95% CI: 37.6-54.1%). The rate in the Chinese population was 47.8% (95% CI: 42.4-53.2%), and in the other countries, it was 38% (95% CI: 23-55%). The serum positive rate for CVA6 antibody was 58.3% (95% CI: 46.5-70.2%). The rate in the Chinese population was 49.1% (95% CI: 38.3-59.9%), and in the other countries, it was 68% (95% CI: 51-83%). Subgroup analysis was also conducted. The seroprevalence of EV-A71 and CVA6 antibodies is related to age rather than gender or region. The rates of EV-A71 and CVA6 seropositivity are considerably lower in children younger than five years of age. However, the rates gradually increase with age. The findings of this study suggest that children under five years of age may be susceptible to EV-A71 and CVA6. Thus, safety education and vaccination should be strengthened accordingly. This study provides a basis for understanding the risk factors for EV-A71 and CVA6 infection in China and for deciding how to formulate standard preventive measures to prevent the spread of the virus.

TMEM173 rs7447927 genetic polymorphism and susceptibility to severe enterovirus 71 infection in Chinese children

INTRODUCTION

This study was designed to explore the association between the TMEM173 polymorphism (rs7447927) and the severity of enterovirus 71 (EV71) infection among Chinese children.

METHODS

The TMEM173 polymorphism was identified in EV71-infected patients (n = 497) and healthy controls (n = 535) using the improved multiplex ligation detection reaction (iMLDR). The interferon-α (IFN-α) serum levels were detected using enzyme linked immunosorbent assay (ELISA).

RESULTS

The frequencies of the GG genotype and G allele of TMEM173 rs7447927 in the mild EV71 infection and severe EV71 infection groups were markedly higher than those in the control group. The GG genotype and G allele frequencies in severely infected EV71 patients were significantly higher than those in mildly infected EV71 patients. Severely infected EV71 patients with the GG genotype had higher white blood cell counts (WBC), and C-reactive proteins (CRP), and blood glucose (BG) levels, longer fever duration, higher vomiting frequency, spirit changes, and electroencephalography (EEG) abnormalities. IFN-α serum concentration in severely infected patients was significantly higher than in the mildly infected group. The IFN-α concentration in the GG genotype was significantly higher compared with those in the GC and CC genotypes in severe cases.

CONCLUSIONS

The TMEM173 rs7447927 polymorphism was associated with EV71 infection susceptibility and severity. The G allele and GG genotype are susceptibility factors in the development of severe EV71 infection in Chinese children.

Association of the IRAK4 rs4251545 genetic polymorphism with severity of enterovirus-71 infection in Chinese children

INTRODUCTION

This study aimed to explore the association between the IRAK4 polymorphism rs4251545 and the severity of enterovirus 71 (EV71) infection in Chinese children.

METHODS

We analyzed the IRAK4 polymorphism rs4251545 in 617 EV71-infected patients and 410 controls using the improved multiplex ligation detection reaction. IRAK4 mRNA expression was tested by qRT-PCR. Serum concentrations of IL-6 and NF-κB were detected using ELISA.

RESULTS

The frequencies of the GA + AA genotype and A allele in the mild EV71 infection group and in the severe EV71 infection group were significantly higher than those in the normal control group. The frequency of the GA + AA genotype and A allele in severely infected EV71 patients was markedly higher than that in mildly infected EV71 patients. IRAK4 mRNA expression in mildly infected EV71 patients and severely infected patients was significantly higher than that in the control group. IRAK4 mRNA expression in GA + AA genotypes in both mild and severe EV71 infection groups was significantly higher than that in patients with the GG genotype. IL-6 concentration and the ratio of IL-6/NF-κB in severe EV71 cases were significantly lower in patients with the GA + AA genotype than in those with the GG genotype. The ratio of IL-6/NF-κB was distinctly higher in severely infected EV71 patients than in mildly infected and control subjects.

CONCLUSIONS

The IRAK4 polymorphism rs4251545 was associated with the susceptibility and severity of EV71 infection. The A allele is a susceptible factor in the development of severe EV71 infection in Chinese children.

Immunogenicity and Safety of Inactivated Enterovirus 71 Vaccine in Children Aged 36-71 Months: A Double-Blind, Randomized, Controlled, Non-inferiority Phase III Trial

BACKGROUND

The Sinovac enterovirus 71 (EV71) vaccine has been given to children aged 6-35 months with good safety, immunogenicity, and efficacy. Further exploration is needed for the application of Sinovac EV71 vaccine in older children.

METHODS

A phase III, double-blind, single-center, randomized, controlled, non-inferiority, and bridging-designed trial enrolled 300 participants aged 6-35 months and 600 participants aged 36-71 months. Non-inferiority and superiority analyses were made to determine the immunogenicity of Sinovac EV71 vaccine in older children (Older-S group), comparing with that of control EV71 vaccine in the same age group (Older-C group), or comparing with that of Sinovac EV71 vaccine in younger children (Younger-S group).

RESULTS

The seroconversion rate of anti-EV71 in Older-S group (95.5%) was superior to that of Older-C group (86.0%), and non-inferior to that of Younger-S group (98.5%). For baseline seronegative participants, the geometric mean titer of Older-S group (370.0) was non-inferior to that of Older-C group (296.2) and superior to that of Younger-S group (176.5). Incidence of adverse reactions in Older-S group (47.0%) was similar to that of Older-C group (44.8%), or Younger-S group (49.8%).

CONCLUSIONS

This study showed good safety and immunogenicity of Sinovac EV71 vaccine in children aged 36-71 months.

CLINICAL TRIALS REGISTRATION

NCT03909074.

URL

https://clinicaltrials.gov/ct2/show/NCT03909074?term=NCT03909074&draw=2&rank=1.

Forecasting hand-foot-and-mouth disease cases using wavelet-based SARIMA-NNAR hybrid model

BACKGROUND

Hand-foot-and-mouth disease_(HFMD) is one of the most typical diseases in children that is associated with high morbidity. Reliable forecasting is crucial for prevention and control. Recently, hybrid models have become popular, and wavelet analysis has been widely performed. Better prediction accuracy may be achieved using wavelet-based hybrid models. Thus, our aim is to forecast number of HFMD cases with wavelet-based hybrid models.

MATERIALS AND METHODS

We fitted a wavelet-based seasonal autoregressive integrated moving average (SARIMA)-neural network nonlinear autoregressive (NNAR) hybrid model with HFMD weekly cases from 2009 to 2016 in Zhengzhou, China. Additionally, a single SARIMA model, simplex NNAR model, and pure SARIMA-NNAR hybrid model were established for comparison and estimation.

RESULTS

The wavelet-based SARIMA-NNAR hybrid model demonstrates excellent performance whether in fitting or forecasting compared with other models. Its fitted and forecasting time series are similar to the actual observed time series.

CONCLUSIONS

The wavelet-based SARIMA-NNAR hybrid model fitted in this study is suitable for forecasting the number of HFMD cases. Hence, it will facilitate the prevention and control of HFMD.

A neonatal murine model of coxsackievirus A4 infection for evaluation of vaccines and antiviral drugs

Coxsackievirus A4 (CVA4) infection can cause hand, foot and mouth disease (HFMD), an epidemic illness affecting neonatal and paediatric cohorts, which can develop to severe neurological disease with high mortality. In this study, we established the first ICR mouse model of CVA4 infection for the evaluation of inactivated vaccines and antiviral drug screening. The CVA4 YT226R strain was selected to infect the neonatal mice and three infectious factors were optimized to establish the infection model. The 3-day-old neonatal mice exhibited clinical symptoms such as hind limb paralysis and death. The severe inflammatory reactions were closely related to the abnormal expression of the acute phase response proinflammatory cytokine IL-6 and an imbalance in the IFN-γ/IL-4 ratio. Importantly, the inactivated CVA4 whole-virus vaccine induced humoral immune responses in adult females and the maternal antibodies afforded mice complete protection against lethal dose challenges of homologous or heterologous CVA4 strains. Both IFN-α2a and antiserum inhibited the replication of CVA4 and increased the survival rates of neonatal mice during the early stages of infection. This neonatal murine model of CVA4 infection will be useful for the development of prophylactic and therapeutic vaccines and for screening of antiviral drugs targeting CVA4 to decrease morbidity and mortality.

Correction: The surveillance of the epidemiological and serotype characteristics of hand, foot, mouth disease in Neijiang city, China, 2010-2017: A retrospective study

[This corrects the article DOI: 10.1371/journal.pone.0217474.].