Epidemiological survey of enterovirus infections occurring in Taiwan between 2000 and 2005: analysis of sentinel physician surveillance data

Investigation of the Correlation between Enterovirus Infection and the Climate Factor Complex Including the Ping-Year Factor and El Niño-Southern Oscillation in Taiwan

Enterovirus infection and enterovirus infection with severe complications (EVSC) are critical issues in several aspects. However, there is no suitable predictive tool for these infections. A climate factor complex (CFC) containing several climate factors could provide more effective predictions. The ping-year factor (PYF) and El Niño-Southern Oscillation (ENSO) are possible CFCs. This study aimed to determine the relationship between these two CFCs and the incidence of enterovirus infection. Children aged 15 years and younger with enterovirus infection and/or EVSC were enrolled between 2007 and 2022. Each year was categorized into a ping-year or non-ping-year according to the PYF. Poisson regression was used to evaluate the associations between the PYF, ENSO, and the incidence of enterovirus infection. Compared to the ping-year group, the incidence rate of enterovirus infection, the incidence rate of EVSC, and the ratio of EVSC in the non-ping-year group were 1.24, 3.38, and 2.73 times higher, respectively (p < 0.001). For every one-unit increase in La Niña, the incidence rate of enterovirus infection decreased to 0.96 times (p < 0.001). Our study indicated that CFCs could be potential predictors for enterovirus infection, and the PYF was more suitable than ENSO. Further research is needed to improve the predictive model.

Study on the epidemiological characteristics of enterovirus among pediatric patients in Hangzhou, China: A comparison between the pre-COVID-19, COVID-19 pandemic, and post-COVID-19 periods

Nonpharmaceutical interventions (NPIs) for coronavirus disease 2019 (COVID-19) not only reduce the prevalence of this disease among children but also influence the transmission of other viruses. This retrospective study investigated the impact of NPIs on human enterovirus (HEV) infection in children diagnosed with hand, foot, and mouth disease (HFMD) or herpangina (HA) in Hangzhou, China. We collected and analyzed the laboratory results and clinical data of children diagnosed with HFMD or HA during the following periods: pre-COVID-19 (January 2019 to December 2019), the COVID-19 pandemic (January 2020 to December 2022), and post-COVID-19 (January to December 2023). A total of 41 742 specimens that met the inclusion criteria were obtained, of which 1998 (4.79%) tested positive for enterovirus. In comparison to those in the pre-COVID-19 period, which had 695 (5.63%) HEV-positive specimens, the numbers dramatically decreased to 69 (1.19%), 398 (5.12%), and 112 (1.58%) in 2020, 2021, and 2022, respectively, but significantly increased to 724 (8.27%) in 2023. Seasonal peaks of infections occurred in May, June, July, and August each year, with the total detection rate ranging from 2019 to 2023 being 9.41% in May, 22.47% in June, 28.23% in July, and 12.16% in August, respectively. The difference in the detection rates of HEV infection between males and females was statistically significant (p < 0.005), with 5.11% (1221/23 898) of males and 4.35% (777/17 844) of females testing positive, resulting in a male-to-female positive ratio of 1.57:1. Among the age groups, 11.25% (378/3360) of the children aged 3-5 years had the highest detection rate, which steadily decreased with increasing or decreasing age. The detection of HEV indicated that >95% of the viruses were other types than the previously commonly reported enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16). In conclusion, NPIs for COVID-19 may be effective at reducing the transmission of HEV. However, with the relaxation of NPIs, the detection rate of HEVs increased slowly to a certain extent. Active awareness and surveillance of the epidemiological characteristics of HEV are essential for preventing, controlling, and managing the development of HFMD and HA, as well as contributing to the development of a multivalent HFMD vaccine.

Genetic and Cross Neutralization Analyses of Coxsackievirus A16 Circulating in Taiwan from 1998 to 2021 Suggest Dominant Genotype B1 can Serve as Vaccine Candidate

Coxsackievirus A16 (CVA16) is well known for causing hand-foot-and-mouth disease (HFMD) and outbreaks were frequently reported in Taiwan in the past twenty years. The epidemiology and genetic variations of CVA16 in Taiwan from 1998 to 2021 were analyzed in this study. CVA16 infections usually occurred in early summer and early winter, and showed increased incidence in 1998, 2000-2003, 2005, 2007-2008, and 2010 in Taiwan. Little or no CVA16 was detected from 2017 to 2021. CVA16 infection was prevalent in patients between 1 to 3 years old. A total of 69 isolates were sequenced. Phylogenetic analysis based on the VP1 region showed that CVA16 subgenotype B1 was dominantly isolated in Taiwan from 1998 to 2019, and B2 was identified only from isolates collected in 1999 and 2000. There was a high frequency of synonymous mutations in the amino acid sequences of the VP1 region among CVA16 isolates, with the exception of position 145 which showed positive selection. The recombination analysis of the whole genome of CVA16 isolates indicated that the 5'-untranslated region and the non-structural protein region of CVA16 subgenotype B1 were recombined with Coxsackievirus A4 (CVA4) and enterovirus A71 (EVA71) genotype A, respectively. The recombination pattern of subgenotype B2 was similar to B1, however, the 3D region was similar to EVA71 genotype B. Cross-neutralization among CVA16 showed that mouse antisera from various subgenotypes viruses can cross-neutralize different genotype with high neutralizing antibody titers. These results suggest that the dominant CVA16 genotype B1 can serve as a vaccine candidate for CVA16.

Whole-genome analysis of coxsackievirus B3 reflects its genetic diversity in China and worldwide

Background

Coxsackievirus B3 (CVB3) has emerged as an active pathogen in myocarditis, aseptic meningitis, hand, foot, and mouth disease (HFMD), and pancreatitis, and is a heavy burden on public health. However, CVB3 has not been systematically analyzed with regard to whole-genome diversity and recombination. Therefore, this study was undertaken to systematically examine the genetic characteristics of CVB3 based on its whole genome.

Methods

We combined CVB3 isolates from our national HFMD surveillance and global sequences retrieved from GenBank. Phylogenetic analysis was performed to examine the whole genome variety and recombination forms of CVB3 in China and worldwide.

Results

Phylogenetic analysis showed that CVB3 strains isolated worldwide could be classified into clusters A–E based on the sequence of the entire VP1 region. The predominant CVB3 strains in China belonged to cluster D, whereas cluster E CVB3 might be circulated globally compared to other clusters. The average nucleotide substitution rate in the P1 region of CVB3 was 4.82 × 10–3 substitutions/site/year. Myocarditis was more common with cluster A. Clusters C and D presented more cases of acute flaccid paralysis, and cluster D may be more likely to cause HFMD. Multiple recombination events were detected among CVB3 variants, and there were twenty-three recombinant lineages of CVB3 circulating worldwide.

Conclusions

Overall, this study provides full-length genomic sequences of CVB3 isolates with a wide geographic distribution over a long-term time scale in China, which will be helpful for understanding the evolution of this pathogen. Simultaneously, continuous surveillance of CVB3 is indispensable to determine its genetic diversity in China as well as worldwide.

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.

Occurrence of various viruses and recent evidence of SARS-CoV-2 in wastewater systems

Viruses are omnipresent and persistent in wastewater, which poses a risk to human health. In this review, we summarise the different qualitative and quantitative methods for virus analysis in wastewater and systematically discuss the spatial distribution and temporal patterns of various viruses (i.e., enteric viruses, Caliciviridae (Noroviruses (NoVs)), Picornaviridae (Enteroviruses (EVs)), Hepatitis A virus (HAV)), and Adenoviridae (Adenoviruses (AdVs))) in wastewater systems. Then we critically review recent SARS-CoV-2 studies to understand the ongoing COVID-19 pandemic through wastewater surveillance. SARS-CoV-2 genetic material has been detected in wastewater from France, the Netherlands, Australia, Italy, Japan, Spain, Turkey, India, Pakistan, China, and the USA. We then discuss the utility of wastewater-based epidemiology (WBE) to estimate the occurrence, distribution, and genetic diversity of these viruses and generate human health risk assessment. Finally, we not only promote the prevention of viral infectious disease transmission through wastewater but also highlight the potential use of WBE as an early warning system for public health assessment.

Viral and Prion Infections Associated with Central Nervous System Syndromes in Brazil

Virus-induced infections of the central nervous system (CNS) are among the most serious problems in public health and can be associated with high rates of morbidity and mortality, mainly in low- and middle-income countries, where these manifestations have been neglected. Typically, herpes simplex virus 1 and 2, varicella-zoster, and enterovirus are responsible for a high number of cases in immunocompetent hosts, whereas other herpesviruses (for example, cytomegalovirus) are the most common in immunocompromised individuals. Arboviruses have also been associated with outbreaks with a high burden of neurological disorders, such as the Zika virus epidemic in Brazil. There is a current lack of understanding in Brazil about the most common viruses involved in CNS infections. In this review, we briefly summarize the most recent studies and findings associated with the CNS, in addition to epidemiological data that provide extensive information on the circulation and diversity of the most common neuro-invasive viruses in Brazil. We also highlight important aspects of the prion-associated diseases. This review provides readers with better knowledge of virus-associated CNS infections. A deeper understanding of these infections will support the improvement of the current surveillance strategies to allow the timely monitoring of the emergence/re-emergence of neurotropic viruses.

Molecular characterization and epidemiological aspects of non-polio enteroviruses isolated from acute flaccid paralysis in Brazil: a historical series (2005-2017)

Due to the advanced stage of polio eradication, the possible role of non-polio enteroviruses (NPEVs) associated to acute flaccid paralysis (AFP) cases has been highlighted. In this study, we described epidemiological aspects of NPEVs infections associated to AFP and explore the viral genetic diversity, information still scarce in Brazil. From 2005 to 2017, 6707 stool samples were collected in the scope of the Brazilian Poliomyelitis Surveillance Program. NPEVs were isolated in 359 samples (5.3%) and 341 (94.9%) were genotyped. About 46 different NPEV types were identified with the following detection pattern EV-B > EV-A > EV-C. The major EV-types were CVA2, CV4, EV-A71, CVB3, CVB5, E6, E7, E11, CVA13 and EV-C99, which corresponds to 51.6% of the total. Uncommon types, such as CVA12, EV-90 and CVA11, were also identified. Different E6 genogroups were observed, prevailing the GenIII, despite periods of co-circulation, and replacement of genogroups along time. CVA2 sequences were classified as genotype C and data suggested its dispersion in South-American countries. CVA13 viruses belonged to cluster B and Venezuelan viruses composed a new putative cluster. This study provides extensive information on enterovirus diversity associated with AFP, reinforcing the need of tailoring current surveillance strategies to timely monitor emergence/re-emergence of NPEVs.

Emergence of Parechovirus A3 as the Leading Cause of Central Nervous System Infection, Surpassing Any Single Enterovirus Type, in Children in Kansas City, Missouri, USA, from 2007 to 2016

Picornaviruses, including Enterovirus species A to D (EV) and Parechovirus species A (PeV-A), are the leading reported causes of pediatric central nervous system infections in the United States. We investigated the molecular epidemiology of EV and PeV-A over 10 years in cerebrospinal fluid (CSF) collected from children seen at Children's Mercy-Kansas City (CMKC) from 2007 through 2016. The overall prevalence for EV was 16% (862/5,362) and 7% (271/4,016) for PeV. Among all picornavirus CSF detections, EV was 76%, and PeV-A was 24%. Multiple EV types cocirculated each year, with a total of 31 EV types detected in the 10-year period; the majority belonged to EV-B species (96%). Two PeV-A types were detected; PeV-A3 was the dominant PeV-A type (95%). The top five picornaviruses (PeV-A3, 26%; E30, 11%; E6, 10%; E18, 9%; E9, 7%) in the CSF of infants accounted for two-thirds of all detections, and PeV-A3 was the leading picornavirus detected. Routine testing and reporting of PeV-A in addition to EV, especially in children under 6 months old with acute febrile illnesses, could reduce hospital stays and antibiotic usage.

Successful containment of horizontal enterovirus infection in a neonatal unit in Singapore through diagnosis by polymerase chain reaction (PCR) and direct sequence analysis

BACKGROUND

Enterovirus (EV) outbreaks often coincide with seasonal peaks in the community. However, they may also sporadically occur in neonatal units. Identification of EV infection in neonates can be challenging, as they tend to present with mild or nonspecific symptoms. This study reports an EV outbreak in the Neonatal Unit at KK Women's and Children's Hospital, Singapore.

METHODS

This is a single-center, retrospective cohort study of neonates who had positive results for EV during the outbreak. Demographic characteristics, clinical presentations and outcomes were analyzed. Control measures used to limit the spread of infection are reported.

RESULTS

A total of 7 cases of EV infection were identified. Their median birth weight and gestational age were 1240 g (750 -2890 g) and 28 weeks (26-35 weeks), respectively. Symptoms occurred at a median age of 48 days (9-103 days). All cases presented initially with recurrent apnea and 4 needed assisted ventilator support with CPAP (2) and mechanical ventilation (2). Serious complications occurred in 3 infants (2 with necrotizing enterocolitis and 1 with meningitis) and none died. EV was detected from rectal swabs (n = 6), CSF (n = 2) and nasopharyngeal swabs (n = 2). Viral subtyping uniformly revealed echovirus 25. Surveillance of all exposed infants by nasopharyngeal swabs was implemented, along with strict contact precautions and cohorting measures.

CONCLUSIONS

Premature infants with EV are more prone to serious complications, which can lead to significant morbidity. Thus, early recognition of symptoms, rapid diagnosis and prompt implementation of infection control measures are key to prevent further spread of infection.

Epidemiological characteristics and spatial-temporal clusters of hand, foot, and mouth disease in Qingdao City, China, 2013-2018

Background

Hand, foot, and mouth disease (HFMD) has become one of the most important infectious diseases recent years. Qingdao City has suffered from serious HFMD epidemic. This study aimed to describe epidemiological characteristics and investigate spatial-temporal distribution at town level in Qingdao City.

Method

The surveillance data of HFMD during 2013–2018 were collected from the National Notifiable Disease Surveillance System. The global Moran’s I statistic was used to detect the spatial autocorrelation of HFMD cases by ArcGis 10.0 software. Purely spatial and spatial-temporal analysis was used to detect epidemic clusters by SatScan^TM v9.6 software.

Results

The annual average incidence of HFMD cases in Qingdao City from 2013 to 2018 was 123.16 per 100000, while the incidence rate of children≤5years old was 2879.80 per 100000. The majority (88.97%) of HFMD cases were aged within 0–5 years old and the males were 60.20%. Other enterovirus (EV), enteriovirus 71(EV71), and Coxsackievirus A16 (CA16) accounted for 48.75%, 30.91% and 20.34%. The seasonal peak was between May and October. HFMD had positive spatial autocorrelation at town level with global Moran’s I from 0.19 to 0.31(P<0.001). Spatial-temporal cluster analysis detected six most likely clusters and three secondary clusters from 2013 to 2018. The most likely cluster was located in urban and urban-rural fringe areas.

Conclusions

Urban and urban-rural fringe areas were the major locations of the clusters with other EV as the dominant pathogen between May and October. The findings suggested that the prevention and control of HFMD in Qingdao City should be focus on these high-risk periods and locations which had important public health significance for the allocation of public health resources.

Respiratory presentation of patients infected with enterovirus D68 in Taiwan

BACKGROUND

Enterovirus-D68 (EV-D68) has been endemic in Taiwan for some years with a small number of positive cases. Detailed information about respiratory presentation is lacking. This study characterized the clinical course in children admitted to the medical center and regional hospital in Taichung during 2015.

METHODS

Retrospective chart review of patients with confirmed EV-D68 infection admitted to the medical center and regional hospital in Taichung with respiratory symptoms in the second half of 2015. Past medical history, clinical presentation, management, and course in hospital were collected and analyzed. Simple demographic data and clinical symptoms were also collected from patients confirmed with EV-D68 infection who visited clinics in Taichung.

RESULTS

Six children were included. Two patients had a prior history of asthma or recurrent dyspnea, and one had other preexisting medical comorbidities. One child was admitted to the pediatric intensive care unit. All the patients were cured. Cough, rhinorrhea, tachypnea and fever were the most common clinical symptoms among inpatients, while influenza-like illness (ILI) was prevalent in outpatients.

CONCLUSION

EV-D68 infection resulted in respiratory presentations of asthma-like illness in the hospitalized pediatric population. Patients with a prior history of asthma or recurrent dyspnea appear to be more severely affected.

Emerging recombination of the C2 sub-genotype of HFMD-associated CV-A4 is persistently and extensively circulating in China

Sporadic outbreaks caused by coxsackievirus A4 (CV-A4) have been reported worldwide. To further elucidate the detailed genetic characteristics and evolutionary recombination events of CV-A4, virus samples from nationwide hand, foot and mouth disease (HFMD) surveillance, encompassing 27 out of the 31 provinces in China, were investigated. Comprehensive and systematic phylogenetic analyses were performed by using 29 complete genomes, 142 complete CV-A4 VP1 sequences. Four genotypes (A, B, C and D) and five sub-genotypes (C1-C5) were re-identified based on the complete VP1 sequences. C2 is the predominant sub-genotype of CV-A4 associated with HFMD and has evolved into 3 clusters. Cluster 1 is a major cluster that has been persistently and extensively circulating in China since 2006 and has been associated with all severe cases. All the sequences showed high homology with the CV-A4 prototype in the P1 region, while higher identities with CV-A5, CV-14 and CV-16 in the P2 and P3 regions. Recombination analysis revealed that C2 had two specific genetic recombination patterns with other EV-A prototypes in the 5'-UTR and 3D region compared with C5. These recombination patterns might be associated with the increased transmissibility of C2 viruses, which were obtained due to their persistent and extensive circulation in populations.

Comparison of Nonpolio Enteroviruses in Children With Herpangina and Hand, Foot and Mouth Disease in Taiwan

BACKGROUND

Nonpolio enterovirus (NPEV) infections are often present with herpangina (HA) and hand, foot and mouth disease (HFMD). Most countries sample NPEVs in HFMD cases, targeting enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) that are associated with outbreaks and severe complications. HA is also monitored in Taiwan and several other countries, but its viral characteristics are underreported.

METHODS

Through Taiwan's National Virologic Surveillance, information regarding ~100,000 child respiratory samples (2002-2015) was linked to concurrent (0-6 days before the sampling date) outpatient records from the National Health Insurance databases, including ~15,000 HA-related and ~7000 HFMD-related samples. We assessed sample representation and NPEV positive rates, and estimated total numbers of EV-A71 and CV-A16.

RESULTS

There were more HA events (4.0 millions) than HFMD events (1.2 millions) in Taiwan. In every 1000 events with HFMD and HA, 6.0 and 4.1, respectively, respiratory samples were collected. The NPEV positive rate in HFMD-related samples was 48%, consistent across most sampling seasons, and predominantly EV-A71 or CV-A16 (74%). By comparison, the HA-related samples had a lower positive rate overall (43%), occasionally EV-A71 or CV-A16 (13%), and the positive rate depended strongly on HA incidence (P < 10). Compared with sampling HFMD alone, inclusion of HA-related information predicted an earlier onset of EV-A71 outbreak in 2011, and predicted 30% more EV-A71 cases.

CONCLUSIONS

This is the first representative report on viral characteristics of HA. Our findings confirm that HFMD monitoring is a reliable strategy, but there is a measurable additional benefit when HA is also monitored.

Epidemiology of Recurrent Hand, Foot and Mouth Disease, China, 2008-2015

Children who have received the enterovirus A71 vaccine are still at risk for disease with infections of enteroviruses of other serotypes.

Using China’s national surveillance data on hand, foot and mouth disease (HFMD) for 2008–2015, we described the epidemiologic and virologic features of recurrent HFMD. A total of 398,010 patients had HFMD recurrence; 1,767 patients had 1,814 cases of recurrent laboratory-confirmed HFMD: 99 reinfections of enterovirus A71 (EV-A71) with EV-A71, 45 of coxsackievirus A16 (CV-A16) with CV-A16, 364 of other enteroviruses with other enteroviruses, 383 of EV-A71 with CV-A16 and CV-A16 with EV-A71, and 923 of EV-A71 or CV-A16 with other enteroviruses and other enteroviruses with EV-A71 or CV-A16. The probability of HFMD recurrence was 1.9% at 12 months, 3.3% at 24 months, 3.9% at 36 months, and 4.0% at 38.8 months after the primary episode. HFMD severity was not associated with recurrent episodes or time interval between episodes. Elucidation of the mechanism underlying HFMD recurrence with the same enterovirus serotype and confirmation that HFMD recurrence is not associated with disease severity is needed.

A case control study on the prevalence of enterovirus in children samples and its association with diarrhea

Some serotypes of enterovirus (EV) may lead to transient and symptomatic gastrointestinal infections while others are commensal residents of the human gut. To determine whether certain EV types are more often associated with diarrhea, we conducted a preliminary study on the prevalence of EV serotypes and common diarrhea viruses in fecal samples of diarrhea children and healthy controls. EV was tested with one step nest polymerase chain reaction and typed by direct sequencing while common causative diarrhea viruses rotavirus (RV), norovirus (NoV), adenovirus (AdV), bocavirus (HBoV), and astrovirus (AstV) were screened with multiplex PCR assays. Human Rhinovirus (HRV) and human EVs that were present in both groups were further quantified and their odds ratios (OR) were calculated. Enteric pathogens were detected in 89 (32.6%) of 273 children with diarrhea and included human EVs (51, 18.68%), HRV (32, 11.72%), RV (38, 13.92%), AdV (24, 8.79%), NoVGII (16, 8.79%), HBoV (8, 2.93%) and AstV (3, 1.09%). Potential enteric pathogens were found in 25 (6.93%) of 361 healthy controls and included human EV (59, 16.34%), HRV (8, 2.22%), RV (1, 0.28%), NoVGII (5, 1.39%), AstV (2, 0.55%), AdV (16, 4.43%) and HBoV (1, 0.28%). In addition, EV71, echovirus 3,9,14,25 and coxsackievirus A14 existed in healthy controls only, while HRV, echovirus11,18, coxsackievirus A2,4,6 and B2,4 were found in both patients and healthy controls. OR assessment confirmed a strong association of HRV (P < 0.001) and a weak one for echovirus 11 and coxsackievirus A6 with diarrhea (P > 0.05). Our results indicate the diversity of EV serotypes in diarrhea and healthy control groups varies, and the potential etiological role of HRV in diarrhea.

Siji Antiviral Mixture Protects against CA16 Induced Brain Injury through Inhibiting PERK/STAT3/NF-κB Pathway

Coxsackievirus 16 (CA16) causes hand, foot, and mouth disease (HFMD) in young children and infants, and it can lead to fatal neurological complications. This study investigated antiviral effects of Siji Antiviral Mixture (SAM) on CA16 in neonatal mice and the protective effects of SAM on CA16 induced brain injuries. Neonatal BALB/c mice and SH-SY5Y cells were used and injected with CA16 stains to study the efficacy. ELISA and Western blotting were used to measure the cytokines levels and proteins expression. Genes transduction was also used to verify interaction mechanism. As the results shown, SAM could reduce the clinical scores at the beginning and delay disease development in vivo. Treatment with SAM decreased the levels of LDH, CK-MB, caspase 3 and Bax, ER stress, and inflammatory reaction induced by CA16 infection. Further siRNA transfection results showed that CA16 induced ER stress and inflammatory reaction through PERK/STAT3/NF-κB signaling and the protective effects of SAM might be through inhibiting PERK/STAT3/NF-κB signaling. HPLC analysis showed fingerprint profiles of SAM had 42 chromatographic peaks. Collectively, our study highlighted distinct roles of SAM in inhibiting CA16 infection and brain injury. The molecular mechanism of SAM might be through inhibiting PERK/STAT3/NF-κB signaling.

Recent development of enterovirus A vaccine candidates for the prevention of hand, foot, and mouth disease

INTRODUCTION

Hand, foot, and mouth disease (HFMD) is a childhood illness commonly caused by enterovirus A. Enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are the most commonly identified viruses associated with HFMD. Recently, outbreaks caused by different enterovirus A including CV-A6 and CV-A10 are increasing. Being available now to protect against EV-A71 infection, inactivated EV-A71 vaccines cannot prevent coxsackievirus infections, thus limiting their general application in controlling HFMD. Multivalent HFMD vaccines are suggested to have broad cross-neutralizing responses against these emerging enteroviruses.

AREAS COVERED

We discuss the recent development of enterovirus A vaccines including the inactivated whole-virion vaccine and virus-like particle vaccine candidates and review the information of neutralization epitopes of these viruses.

EXPERT COMMENTARY

Evaluation of the efficacy and safety of the coxsackievirus vaccine and the multivalent HFMD vaccine candidates in clinical trials is urgently required. Epitopic analysis showed that common immunodominant sites exist across these enteroviruses. However, variations of amino acid residues in these regions limit the induction of cross-neutralization antibodies, and therefore, a multivalent HFMD vaccine is required for broad protection against HFMD. With the inclusion of major circulating viruses in the development of multivalent HFMD vaccines, an increase in the success in HFMD control is anticipated.

High frequency of Polio-like Enterovirus C strains with differential clustering of CVA-13 and EV-C99 subgenotypes in a cohort of Malawian children

Enteroviruses (EVs) are among the most commonly detected viruses infecting humans worldwide. Although the prevalence of EVs is widely studied, the status of EV prevalence in sub-Saharan Africa remains largely unknown. The objective of our present study was therefore to increase our knowledge on EV circulation in sub-Saharan Africa. We obtained 749 fecal samples from a cross-sectional study conducted on Malawian children aged 6 to 60 months. We tested the samples for the presence of EVs using real time PCR, and typed the positive samples based on partial viral protein 1 (VP1) sequences. A large proportion of the samples was EV positive (89.9%). 12.9% of the typed samples belonged to EV species A (EV-A), 48.6% to species B (EV-B) and 38.5% to species C (EV-C). More than half of the EV-C strains (53%) belonged to subgroup C containing, among others, Poliovirus (PV) 1-3. The serotype most frequently isolated in our study was CVA-13, followed by EV-C99. The strains of CVA-13 showed a vast genetic diversity, possibly representing a new cluster, 'F'. The majority of the EV-C99 strains grouped together as cluster B. In conclusion, this study showed a vast circulation of EVs among Malawian children, with an EV prevalence of 89.9%. Identification of prevalences for species EV-C comparable to our study (38.5%) have only previously been reported in sub-Saharan Africa, and EV-C is rarely found outside of this region. The data found in this study are an important contribution to our current knowledge of EV epidemiology within sub-Saharan Africa.

Changes of circulating Th22 cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection

Interleukin (IL)-22+CD4+T (Th22) cells play crucial roles in the pathogenesis of autoimmune diseases and infectious diseases, although the role of Th22 cells remains largely unclear in children with hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71). This study aims to explore the role of circulating IL-22+IL-17A-CD4+T (cTh22) cells in children with EV71-associated HFMD. We found that during the acute stage of illness, the frequencies of cTh22 and circulating IL-22+IL-17A+CD4+T (IL-22+cTh17) cells in CD4+T cells infrom affected patients, and especially in severely affected patients, were significantly higher than in healthy controls (HC). The major source of IL-22 production was cTh22 cells, partially from cTh17 cells. Moreover, the protein and mRNA levels of IL-22, IL-17A, IL-23, IL-6, and TNF-α were significantly different among the mild patients, severe patients and HC, as well as AHR and RORγt mRNA levels. A positive correlation was found between plasma IL-22 levels and cTh22 cell frequencies, and cTh17 cell and IL-22+ cTh17 cell frequencies. Furthermore, the frequencies of cTh22 were significantly decreased in the convalescent patients. Our findings indicated that cTh22 cells could play critical roles in the pathogenesis of EV71 infection, and are potential therapeutic targets for patients with EV71-associated HFMD.

Comparison of clinical and laboratory characteristics during two major paediatric meningitis outbreaks of echovirus 30 and other non-polio enteroviruses in Germany in 2008 and 2013

Viral meningitis is mainly caused by non-polio enteroviruses (NPEV). Large-scale data on the clinical characteristics between different outbreaks within the same region are lacking. This study aimed to analyse a possible influence of the circulating NPEV genotype on the disease outcome of affected children. A retrospective cohort study analysing two major outbreaks of NPEV meningitis in Germany in 2008 and 2013 was conducted in cooperation with the National Reference Centre for Poliomyelitis and Enteroviruses (NRC PE) and five German children's hospitals. A total of 196 patients with laboratory-confirmed NPEV meningitis were enrolled. In 2008, children with NPEV meningitis had significantly higher fever and showed more behavioural changes and less back pain. To better define typical findings in echovirus 30 (E-30) meningitis, patients were split into the following three groups: E-30 positive patients, patients with "Non E-30" infection and patients with "Untyped" NPEV infection. E-30 positive patients were significantly older and their disease course was more acute, with early admission to but also early discharge from hospital. E-30 positive patients showed a significantly higher rate of headache and meningism, and a lower rate of diarrhoea and clinically defined septicaemia when compared to the others. Regarding laboratory testing, E-30 positive patients presented with significantly elevated peripheral blood neutrophil counts when compared to patients with "Non E-30" or "Untyped" NPEV infection. In conclusion, E-30 meningitis in children shows a characteristic pattern of clinical features. To further characterise NPEV strains worldwide, continuous surveillance and typing of NPEV strains causing central nervous system disease is warranted.

Peculiar Clinical Presentation of Coxsackievirus B4 Infection: Neonatal Restrictive Cardiomyopathy

Introduction  Restrictive cardiomyopathy in fetuses and neonates is extremely rare and has a poor outcome. Its etiology in neonates is elusive: metabolic diseases (e.g., Gaucher, Hurler syndrome), neuromuscular disorders (e.g., muscular dystrophies, myofibrillar myopathies), or rare presentation of genetic syndromes (e.g., Coffin-Lowry syndrome) account for a minority of the cases, the majority remaining idiopathic. Case Study  We report the case of a 17-day-old male infant presenting cardiogenic shock following a restrictive dysfunction of the left ventricle. Postmortem investigations revealed coxsackievirus B4 myocarditis with histological lesions limited to the left heart. However, polymerase chain reaction (PCR) for coxsackievirus B4 was positive in the left as well as in the right ventricular samples. Conclusion  In conclusion, coxsackievirus myocarditis is a cause of restrictive cardiomyopathy, and its diagnosis should involve PCR screening as a more sensitive technique.

Molecular epidemiology of the enteroviruses associated with hand, foot and mouth disease/herpangina in Dongguan, China, 2015

Enteroviruses (EVs) are the etiological agents involved in most cases of hand, foot and mouth disease (HFMD) and herpangina (HA). Information on the epidemiology profiles of EVs in China is very limited, as the present surveillance system of China focuses on CAV16 and EV71, and no published data are available in Dongguan. The aim of this study is to determine the prevalence of EVs among patients with HFMD and HA in Dongguan, China, during 2015. A total of 271 clinical stool specimens that were clinically determined to be positive for enteroviruses were genotyped by semi-nested polymerase chain reaction (PCR) for the VP1 genes of EVs. The results showed that a total of 14 enterovirus genotypes were identified among HFMD and HA patients in this study. CVA6 was the most common genotype for HFMD, and CVA2 accounted for the majority of HA cases in this study. Sequence and phylogenetic analysis showed that all of the CVA6 and CVA2 strains identified in our study displayed a close genetic relationship to strains identified in other cities in China. This study also demonstrates that there are associations between particular causative enterovirus genotypes and some clinical symptoms, which may provide useful information for improving case prevention, diagnosis and treatment of HFMD and HA.

Severe Enterovirus Infections in Hospitalized Children in the South of England: Clinical Phenotypes and Causative Genotypes

BACKGROUND

Most enterovirus surveillance studies lack detailed clinical data, which limits their clinical usefulness. This study aimed to describe the clinical spectrum and outcome of severe enterovirus infections in children, and to determine whether there are associations between causative enterovirus genotypes and clinical phenotypes.

METHODS

Retrospective analysis of microbiological and clinical data from a tertiary children's hospital in the South of England over a 17-month period (2012-2013).

RESULTS

In total, 30 patients were identified, comprising sepsis (n = 9), myocarditis (n = 8), meningitis (n = 8) and encephalitis (n = 5). Cases with sepsis or myocarditis were significantly younger than those with central nervous system disease (median age 21 and 15 days vs. 79 days; P = 0.0244 and P = 0.0310, respectively). There was considerable diversity in the causative genotypes in each of the clinical phenotypes, with some predominance of echoviruses in the meningitis group, and coxsackie B viruses in the myocarditis group. Thirteen cases required mechanical ventilation, 11 cases inotropic support, 3 cases dialysis and 3 cases extracorporal membrane oxygenation. The overall mortality was 10% (sepsis group, n = 1; myocarditis group, n = 2). Of the survivors, 5 (19%) had long-term sequelae (myocardial dysfunction, n = 2; neurological sequelae, n = 3). Patients with encephalitis had the longest hospital stay (median: 16 days), compared with 9, 6 and 3 days in patients with myocarditis, sepsis and meningitis, respectively (P = 0.005).

CONCLUSIONS

Enterovirus infections, particularly enteroviral myocarditis and encephalitis, can cause significant morbidity and mortality. The results show that there are currently no strong associations between clinical phenotypes and particular causative enterovirus genotypes in the South of England.

A rapid and quantitative assay for measuring neutralizing antibodies of Coxsackievirus B3

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We have established a robust single round infection system of CVB3.

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A new quantitative assay for measuring NtAb of CVB3 in clinical samples.

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Seroprevalence of CVB3 in pre-school children is lower than that in adults.

Coxsackievirus B3 (CVB3) infection has been found to account for an increasing proportion cases of hand, foot and mouth disease (HFMD) in recent epidemiology studies. CVB3 is a single stranded, non-enveloped RNA virus and the infection can cause prominent health threat to pre-school children. Here, by taking approaches of reverse genetics, we established a single-round infection system for CVB3. The pseudovirus was produced by sequential transfection of CVB3 capsid expresser plasmid and CVB3 replicon RNA bearing firefly luciferase as a reporter. The CVB3 pseudovirus system was used for quantifying neutralizing antibody (NtAb) levels of 720 human serum samples and showed superior specificity and sensitivity comparing traditional cytopathic effect (CPE) assay. Furthermore, we compared the seroprevalence of CVB3 NtAbs in pre-school children and healthy adults, and found that only 11.94% of pre-school children were NtAbs positive which suggested that most children were naive to CVB3 infection; while there is much higher positive rate in adults (60%) indicating that most adults have experienced CVB3 infection during childhood. This rapid and quantitative assay greatly facilitates evaluating the level of NtAbs against CVB3 in populations and will help to advance CVB3 vaccine development.

Genotyping of enteroviruses isolated in Kenya from pediatric patients using partial VP1 region

Enteroviruses (EV) are responsible for a wide range of clinical diseases in humans. Though studied broadly in several regions of the world, the genetic diversity of human enteroviruses (HEV) circulating in the sub-Saharan Africa remains under-documented. In the current study, we molecularly typed 61 HEV strains isolated in Kenya between 2008 and 2011 targeting the 3′-end of the VP1 gene. Viral RNA was extracted from the archived isolates and part of the VP1 gene amplified by RT-PCR, followed by sequence analysis. Twenty-two different EV types were detected. Majority (72.0 %) of these belonged to Enterovirus B species followed by Enterovirus D (21.3 %) and Enterovirus A (6.5 %). The most frequently detected types were Enterovirus-D68 (EV-D68), followed by Coxsackievirus B2 (CV-B2), CV-B1, CV-B4 and CV-B3. Phylogenetic analyses of these viruses revealed that Kenyan CV-B1 isolates were segregated among sequences of global CV-B1 strains. Conversely, the Kenyan CV-B2, CV-B3, CV-B4 and EV-D68 strains generally grouped together with those detected from other countries. Notably, the Kenyan EV-D68 strains largely clustered with sequences of global strains obtained between 2008 and 2010 than those circulating in recent years. Overall, our results indicate that HEV strains belonging to Enterovirus D and Enterovirus B species pre-dominantly circulated and played a significant role in pediatric respiratory infection in Kenya, during the study period. The Kenyan CV-B1 strains were genetically divergent from those circulating in other countries. Phylogenetic clustering of Kenyan EV-D68 strains with sequences of global strains circulating between 2008 and 2010 than those obtained in recent years suggests a high genomic variability associated with the surface protein encoding VP1 gene in these enteroviruses.

Immunological and biochemical characterizations of coxsackievirus A6 and A10 viral particles

Childhood exanthema caused by different serotypes of coxsackievirus (CV-A) and enterovirus A71 (EV-A71) has become a serious global health problem; it is commonly known as hand, foot, and mouth disease (HFMD). Current EV-A71 vaccine clinical trials have demonstrated that human antibody responses generated by EV-A71 vaccinations do not cross-neutralize coxsackievirus A16 (CV-A16). An effective multivalent HFMD vaccine is urgently needed. From molecular epidemiological studies in Southeast Asia, CV-A6 and CV-A10 are commonly found in HFMD outbreaks. In this study, CV-A6 and CV-A10 were individually cultured in rhabdomyosarcoma (RD) cells grown in medium containing serum, harvested and concentrated. In viral downstream purification, two viral fractions were separated by sucrose gradient zonal ultracentrifugation and detected using a SDS-PAGE analysis and a virus infectivity assay. These two viral fractions were formalin-inactivated, and only the infectious particle fraction was found to be capable of inducing CV-A serotype-specific neutralizing antibody responses in animal immunogenicity studies. These mouse and rabbit antisera also failed to cross-neutralize EV-A71 and CV-A16 infections. Only a combination of formalin-inactivated EV-A71, CV-A6, CV-A10 and CV-A16 multivalent vaccine candidates elicited cross-neutralizing antibody responses in both mouse and rabbit immunogenicity studies. The current results certainly provide important information for multivalent HFMD vaccine development.

Impact of Human Enterovirus 71 Genotypes in Meningoencephalitis in Iran

Background:

Since the importance of poliovirus has diminished, as a result of its elimination in the majority of countries, non-polioviruses are emerging as causative agents of severe central nervous system (CNS) involvement. Outbreaks of enterovirus 71 (EV71)-associated CNS infections have recently been reported in Asia, Australia, and Europe.

Objectives:

This is the first study on genotyping of EV71 in children with meningoencephalitis to be carried out in Iran, and it was conducted in order to obtain an improved understanding of the disease burden of this virus, particularly with regard to CNS involvement.

Patients and Methods:

Viral RNA was extracted from 170 cerebrospinal fluid samples obtained from children aged under 8 years with a primary diagnosis of aseptic meningitis. Specific EV71 PCR was conducted to identify the genotype of the detected EV71 viruses.

Results:

Human enteroviruses (HEVs) were detected in 89 patients (52.3%). EV71 infection was detected in 19 (21.3%) of the 89 EV71-positive patients, and the C genotype was identified in 15 isolates.

Conclusions:

The C genotype should be considered as the prevalent EV71 circulating genotype in Iran, particularly in cases of aseptic meningitis.

Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination

BACKGROUND

Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus.

METHODS AND FINDINGS

Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible-infected-recovered (TSIR) epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40) and 27.13 for CV-A16 (IQR: 23.15, 31.34), with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation). EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the post-EV-A71-vaccination period remained either comparable to or only slightly increased from levels prior to vaccination. The duration and strength of cross-protection following infection with EV-A71 or CV-A16 was estimated to be 9.95 wk (95% confidence interval [CI]: 3.31, 23.40) in 68% of the population (95% CI: 37%, 96%). Our predictions are limited by the necessarily short and under-sampled time series and the possible circulation of unidentified serotypes, but, nonetheless, sensitivity analyses indicate that our results are robust in predicting that the vaccine should drastically reduce incidence of EV-A71 without a substantial competitive release of CV-A16.

CONCLUSIONS

The ability of our models to capture the observed epidemic cycles suggests that herd immunity is driving the epidemic dynamics caused by the multiple serotypes of enterovirus. Our results predict that the EV-A71 and CV-A16 serotypes provide a temporary immunizing effect against each other. Achieving high coverage rates of EV-A71 vaccination would be necessary to eliminate the ongoing transmission of EV-A71, but serotype replacement by CV-A16 following EV-A71 vaccination is likely to be transient and minor compared to the corresponding reduction in the burden of EV-A71-associated HFMD. Therefore, a mass EV-A71 vaccination program of infants and young children should provide significant benefits in terms of a reduction in overall HFMD burden.

Latitude-based approach for detecting aberrations of hand, foot, and mouth disease epidemics

Background

Epidemics of hand, foot and mouth disease (HFMD) among children in East Asia have been a serious annual public health problem. Previous studies in China and island-type territories in East Asia showed that the onset of HFMD epidemics evolved with increased latitude. Based on the natural characteristics of the epidemics, we developed regression models for issuing aberration alerts and predictions.

Methods

HFMD sentinel surveillance data from 2008 to 2014 in Japan are used in this study, covering 365 weeks and 47 prefectures between 24 and 46° of north latitude. Average HFMD cases per sentinel are standardized as Z rates. We fit weekly Z rate differences between prefectures located in the south and north of a designated prefecture with linear regression models to detect the surging trend of the epidemic for the prefecture. We propose a rule for issuing an aberration alert determined by the strength of the upward trend of south–north Z rate differences in the previous few weeks. In addition to the warning, we predict a Z rate for the next week with a 95 % confidence interval.

Results

We selected Tokyo and Kyoto for evaluating the proposed approach to aberration detection. Overall, the peaks of epidemics in Tokyo mostly occurred in weeks 28–31, later than in Kyoto, where the disease peaked in weeks 26–31. Positive south–north Z rate differences in both prefectures were clearly observed ahead of the HFMD epidemic cycles. Aberrations in the major epidemics of 2011 and 2013 were successfully detected weeks earlier. The prediction also provided accurate estimates of the epidemic’s trends.

Conclusions

We have used only the latitude, one geographical feature affecting the spatiotemporal distribution of HFMD, to develop rules for early aberration detection and prediction. We have also demonstrated that the proposed rules performed well using real data in terms of accuracy and timeliness. Although our approach may provide helpful information for controlling epidemics and minimizing the impact of diseases, the performance could be further improved by including other influential meteorological factors in the proposed latitude-based approach, which is worth further investigation.

Visualized Exploratory Spatiotemporal Analysis of Hand-Foot-Mouth Disease in Southern China

OBJECTIVES

In epidemiological research, major studies have focused on theoretical models; however, few methods of visual analysis have been used to display the patterns of disease distribution.

DESIGN

For this study, a method combining the space-time cube (STC) with space-time scan statistics (STSS) was used to analyze the pattern of incidence of hand-foot-mouth disease (HFMD) in Guangdong Province from May 2008 to March 2009. In this research, STC was used to display the spatiotemporal pattern of incidence of HFMD, and STSS were used to detect the local aggregations of the disease.

SETTING

The hand-foot-mouth disease data were obtained from Guangdong Province from May 2008 to March 2009, with a total of 68,130 cases.

RESULTS

The STC analysis revealed a differential pattern of HFMD incidence among different months and cities and also showed that the population density and average precipitation are correlated with the incidence of HFMD. The STSS analysis revealed that the most likely aggregation includes the Shenzhen, Foshan and Dongguan populations, which are the most developed regions in Guangdong Province.

CONCLUSION

Both STC and STSS are efficient tools for the exploratory data analysis of disease transmission. STC clearly displays the spatiotemporal patterns of disease. Using the maximum likelihood ratio, the STSS model precisely locates the most likely aggregation.

Effect of Meteorological and Geographical Factors on the Epidemics of Hand, Foot, and Mouth Disease in Island-Type Territory, East Asia

Hand, foot, and mouth disease (HFMD) has threatened East Asia for more than three decades and has become an important public health issue owing to its severe sequelae and mortality among children. The lack of effective treatment and vaccine for HFMD highlights the urgent need for efficiently integrated early warning surveillance systems in the region. In this study, we try to integrate the available surveillance and weather data in East Asia to elucidate possible spatiotemporal correlations and weather conditions among different areas from low to high latitude. The general additive model (GAM) was applied to understand the association between HFMD and latitude, as well as meteorological factors for islands in East Asia, namely, Japan, Taiwan, Hong Kong, and Singapore, from 2012 to 2014. The results revealed that latitude was the most important explanatory factor associated with the timing and amplitude of HFMD epidemics (P < 0.0001). Meteorological factors including higher dew point, lower visibility, and lower wind speed were significantly associated with the rise of epidemics (P < 0.01). In summary, weather conditions and geographic location could play some role in affecting HFMD epidemics. Regional integrated surveillance of HFMD in East Asia is needed for mitigating the disease risk.

Transmission and Demographic Dynamics of Coxsackievirus B1

The infectious activity of coxsackievirus B1 (CV-B1) in Taiwan was high from 2008 to 2010, following an alarming increase in severe neonate disease in the United States (US). To examine the relationship between CV-B1 strains isolated in Taiwan and those from other parts of the world, we performed a phylodynamic study using VP1 and partial 3Dpol (414 nt) sequences from 22 strains of CV-B1 isolated in Taiwan (1989-2010) and compared them to sequences from strains isolated worldwide. Phylogenetic trees were constructed by neighbor-joining, maximum likelihood, and Bayesian Monte Carlo Markov Chain methods. Four genotypes (GI-IV) in the VP1 region of CV-B1 and three genotypes (GA-C) in the 3Dpol region of enterovirus B were identified and had high support values. The phylogenetic analysis indicates that the GI and GIII strains in VP1 were geographically distributed in Taiwan (1993-1994) and in India (2007-2009). On the other hand, the GII and GIV strains appear to have a wider spatiotemporal distribution and ladder-like topology A stair-like phylogeny was observed in the VP1 region indicating that the phylogeny of the virus may be affected by different selection pressures in the specified regions. Further, most of the GI and GII strains in the VP1 tree were clustered together in GA in the 3D tree, while the GIV strains diverged into GB and GC. Taken together, these data provide important insights into the population dynamics of CV-B1 and indicate that incongruencies in specific gene regions may contribute to spatiotemporal patterns of epidemicity for this virus.

Epidemiological characteristics and influential factors of hand, foot and mouth disease (HFMD) reinfection in children in Anhui province

Hand, foot and mouth disease (HFMD) is an acute contagious condition caused by a spectrum of human enteroviruses. HFMD reinfection is common in the absence of cross-protection from other virus subtypes. This study focused on reinfection in children in Anhui province, China between 2008 and 2013 using surveillance system data. We classified 8960 cases as reinfected, corresponding to a rate of 2·02%. The reinfection rate was higher in boys than in girls [odds ratio (OR) 1·27, 95% confidence interval (CI) 1·21-1·32, P < 0·001], children aged < 3 years (OR 3·82, 95% CI 3·58-4·07, P < 0·001), and children living in rural areas (OR 1·09, 95% CI 1·04-1·14, P = 0·001). The reinfection rate in children who were originally infected with non-enterovirus A71 (non-EVA71) enteroviruses was higher than those infected with EVA71 (OR 1·36, 95% CI 1·02-1·80, P = 0·034). Influential factors of reinfection rate included annual incidence (β coefficient = 0·715, P = 0·002) and the proportion of EVA71 in patients with mild HFMD (β coefficient = -0·509, P = 0·018). These results demonstrate that boys aged <3 years, especially those in rural areas or regions with a lower EVA71 proportion are more prone to reinfection, and specific health education programmes should be developed to protect these susceptible populations.

Massive pulmonary hemorrhage in enterovirus 71-infected hand, foot, and mouth disease

Hand, foot, and mouth disease (HFMD) is an acute, mostly self-limiting infection. Patients usually recover without any sequelae. However, a few cases are life threatening, especially those caused by enterovirus 71 (EV71). A 12-month-old boy was admitted to a primary hospital with high fever and vesicular lesions of the mouth, hands, and feet. After 3 days, he experienced 3 seizure episodes and was referred to our hospital. On admission, he was conscious and his chest radiograph was normal. However, 6 hours later, he suddenly lost consciousness and had developed a massive pulmonary hemorrhage that continued until his death. He experienced several more intermittent seizures, and diffuse infiltration of both lung fields was observed on chest radiography. Intravenous immunoglobulin, dexamethasone, cefotaxime, leukocyte-depleted red blood cells, fresh frozen plasma, inotropics, vitamin K, and endotracheal epinephrine were administered. The patient died 9 hours after intubation, within 3 days from fever onset. EV71 subgenotype C4a was isolated retrospectively from serum and nasopharyngeal swab by real-time reverse transcription-polymerase chain reaction. Here, we report a fatal case of EV71-associated HFMD with sudden-onset massive pulmonary hemorrhage and suspected encephalitis.

Mapping of a quantitative trait locus controlling susceptibility to Coxsackievirus B3-induced viral hepatitis

The pathogenesis of coxsackieviral infection is a multifactorial process involving host genetics, viral genetics and the environment in which they interact. We have used a mouse model of Coxsackievirus B3 infection to characterize the contribution of host genetics to infection survival and to viral hepatitis. Twenty-five AcB/BcA recombinant congenic mouse strains were screened. One, BcA86, was found to be particularly susceptible to early mortality; 100% of BcA86 mice died by day 6 compared with 0% of B6 mice (P=0.0012). This increased mortality was accompanied by an increased hepatic necrosis as measured by serum alanine aminotransferase (ALT) levels (19547±10556 vs 769±109, P=0.0055). This occurred despite a predominantly resistant (C57BL/6) genetic background. Linkage analysis in a cohort (n=210) of (BcA86x C56Bl/10)F2 animals revealed a new locus on chromosome 13 (peak linkage 101.2 Mbp, lod 4.50 and P=0.003). This locus controlled serum ALT levels as early as 48 h following the infection, and led to an elevated expression of type I interferon. Another locus on chromosome 17 (peak linkage 57.2 Mbp) was significantly linked to heart viral titer (lod 3.4 and P=0.046). These results provide new evidence for the presence of genetic loci contributing to the susceptibility of mice to viral hepatitis.

Molecular epidemiology of coxsackievirus A6 associated with outbreaks of hand, foot, and mouth disease in Tianjin, China, in 2013

Since 2008, Mainland China has undergone widespread outbreaks of hand, foot, and mouth disease (HFMD). In order to determine the characteristics of epidemics and enteroviruses (EV) associated with HFMD in Tianjin, in northern China, epidemiological and virological data from routine surveillance were collected and analyzed. In Tianjin, a persistent epidemic of HFMD was demonstrated during 2008-2013, involving 102,705 mild, 179 severe, and 16 fatal cases. Overall, 8234 specimens were collected from 7829 HFMD patients for EV detection during 2008-2013. Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) were the dominant serotypes during 2008-2012, and they were replaced by CV-A6 as the major causative agent in 2013. Phylogenetic analysis based on complete VP1 nucleotide sequences revealed that multiple CV-A6 lineages co-circulated in Tianjin, which grouped together with strains from China and other countries and split into two distinct clusters (clusters 1 and 2). Most Tianjin strains grouped in cluster 1 and were closely related to strains from several eastern and southern provinces of China during 2012 and 2013. Estimates from Bayesian MCMC analysis suggested that multiple lineages had been transmitted silently before the outbreaks at an estimated evolutionary rate of 4.10 × 10(-3) substitutions per site per year without a specific distribution of rate variances among lineages. The sudden outbreak of CV-A6 in Tianjin during 2013 is attributed to indigenous CV-A6 lineages, which were linked to the wide spread of endemic strains around eastern and southern China.

Epidemiological Characteristics and Spatial-Temporal Clusters of Hand, Foot, and Mouth Disease in Zhejiang Province, China, 2008-2012

Hand, foot and mouth disease (HFMD) is one of the major public health concerns in China. Being the province with high incidence rates of HFMD, the epidemiological features and the spatial-temporal patterns of Zhejiang Province were still unknown. The objective of this study was to investigate the epidemiological characteristics and the high-incidence clusters, as well as explore some potential risk factors. The surveillance data of HFMD during 2008-2012 were collected from the communicable disease surveillance network system of Zhejiang Provincial Center for Disease Control and Prevention. The distributions of age, gender, occupation, season, region, pathogen's serotype and disease severity were analyzed to describe the epidemiological features of HFMD in Zhejiang Province. Seroprevalence survey for human enterovirus 71 (EV71) in 549 healthy children of Zhejiang Province was also performed, as well as 27 seroprevalence publications between 1997 and 2015 were summarized. The spatial-temporal methods were performed to explore the clusters at county level. Furthermore, pathogens' serotypes such as EV71 and coxsackievirus A16 (Cox A16) and meteorological factors were analyzed to explore the potential factors associated with the clusters. A total of 454,339 HFMD cases were reported in Zhejiang Province during 2008-2012, including 1688 (0.37%) severe cases. The annual average incidence rate was 172.98 per 100,000 (ranged from 72.61 to 270.04). The male-to-female ratio for mild cases was around 1.64:1, and up to 1.87:1 for severe cases. Of the total cases, children aged under three years old and under five years old accounted for almost 60% and 90%, respectively. Among all enteroviruses, the predominant serotype was EV71 (49.70%), followed by Cox A16 (26.05%) and other enteroviruses (24.24%) for mild cases. In severe cases, EV71 (82.85%) was the major causative agent. EV71 seroprevalence survey in healthy children confirmed that occult infection was common in children. Furthermore, literature summary for 26 seroprevalence studies during 1997-2015 confirmed that 0-5 years group showed lowest level of EV71 seroprevalence (29.1% on average) compared to the elder children (6-10 years group: 54.6%; 11-20 years group: 61.8%). Global positive spatial autocorrelation patterns (Moran's Is>0.25, P<0.05) were discovered not only for mild cases but also for severe cases, and local positive spatial autocorrelation patterns were revealed for counties from the eastern coastal and southern regions. The retrospective space-time cluster analysis also confirmed these patterns. Risk factors analyses implied that more EV71 and less sunshine were associated with the clusters of HFMD in Zhejiang Province. Our study confirmed that Zhejiang Province was one of the highly epidemic provinces in China and that the epidemiological characteristics of HFMD were similar to other provinces. Occult infection in elder children and adults was one of the important reasons why most HFMD cases were children aged under-five. Combining the results of spatial autocorrelation analysis and the space-time cluster analysis, the major spatial-temporal clusters were from the eastern coastal and southern regions. The distribution of pathogens' serotypes and the level of sunshine could be risk factors for, and serve as an early warning of, the outbreak of HFMD in Zhejiang Province.

Presence of human non-polio enterovirus and parechovirus genotypes in an Amsterdam hospital in 2007 to 2011 compared to national and international published surveillance data: a comprehensive review

Enteroviruses (EV) and human parechoviruses (HPeV) are endemic worldwide. These infections are a constant cause of hospitalisation and severe disease, predominantly in young children and infants. Coordinated monitoring and surveillance are crucial to control these infections. We have monitored EV and HPeV epidemiology in Amsterdam from 2007 to 2011 with real-time RT-PCR and direct genotyping, facilitating highly sensitive surveillance. Moreover, we conducted a literature survey of existing surveillance data for comparison. Only 14 studies were identified. While HPeV1 was most frequently detected in Amsterdam, EV-B viruses dominated nationally and internationally. Furthermore, the top 10 strains detected differed yearly and per study. However, detection and typing methods were too varied to allow direct comparison and comprehension of the worldwide distribution and circulation patterns of the different genotypes. This limited a direct response to anticipate peaks. Uniform European monitoring programmes are essential to aid prediction of outbreaks and disease management.

Risk factors for critical disease and death from hand, foot and mouth disease

BACKGROUND

There has been a high mortality and morbidity rate of critical and fatal patients from hand, foot and mouth disease (HFMD) in China in recent. Causes for development of critical and fatal disease remain unclear.

METHODS

We performed a case-control study to assess the association between use of drugs and development of critical disease and death from HFMD.

RESULTS

We found that glucocorticoids treatment was associated with a greater incidence of severe HFMD, whereas andrographolides treatment was associated with a protective effect when they are used for treatment within 48 hours after onset or before being diagnosed as critical.

CONCLUSIONS

We recommend that glucocorticoids should not be used for mild HFMD and andrographolides should undergo clinical trials for treatment of enterovirus 71 infections.

Molecular and epidemiological study of human parechovirus infections in Taiwan, 2007-2012

BACKGROUND/PURPOSE

As routine diagnostic assays for human parechoviruses (HPeVs) have not been included in the enteroviruses surveillance network in Taiwan, HPeVs may be the actual pathogens of hundreds of untypeable enteroviruses-suspected isolates.

METHODS

In this study, these untypeable isolates collected from 2007 through 2012 were examined by reverse transcription-polymerase chain reaction (RT-PCR)-based methods to survey the epidemiology of HPeVs in Taiwan.

RESULTS

Thirty-eight HPeV isolates were identified from 575 untypeable isolates, including 23 HPeV type1 (HPeV1), 13 HPeV3, and two HPeV6. Most of the patients were Taiwanese children under 5 years of age and their infections were generally prevalent in summer and autumn, with the highest peak occurring in September. The ratio of male to female patients was 1.56 and 2.25 for HPeV1 and HPeV3, respectively. Fever and respiratory symptoms were reported in significantly more patients infected with HPeV1. The results of phylogenetic analyses showed that HPeV isolates between 2007 and 2012 belonged to different lineages, indicating that endemic circulation of HPeV existed in Taiwan.

CONCLUSION

This study showed that HPeVs have been endemic in Taiwan for some years despite a low positive rate. The detection tests of HPeVs are needed to correct a diagnostic deficit in the surveillance system. The epidemiological and genetic information obtained from the present study would contribute to the understanding of the etiology and epidemiology of HPeVs.

Prevalence and characterization of enterovirus infections among pediatric patients with hand foot mouth disease, herpangina and influenza like illness in Thailand, 2012

Hand, foot, and mouth disease (HFMD) and herpangina are common infectious diseases caused by several genotypes of human enterovirus species A and frequently occurring in young children. This study was aimed at analyzing enteroviruses from patients with these diseases in Thailand in 2012. Detection and genotype determination of enteroviruses were accomplished by reverse transcription-polymerase chain reaction and sequencing of the VP1 region. Enterovirus-positive samples were differentiated into 17 genotypes (coxsackievirus A4 (CAV4), A5, A6, A8, A9, A10, A12, A16, A21, B1, B2, B4, B5, echovirus 7, 16, 25 and Enterovirus 71). The result showed CAV6 (33.5%), followed by CAV16 (9.4%) and EV71 (8.8%) as the most frequent genotypes in HFMD, CAV8 (19.3%) in herpangina and CAV6 (1.5%) in influenza like illness. Enterovirus infections were most prevalent during July with 34.4% in HFMD, 39.8% in herpangina and 1.6% in ILI. The higher enterovirus infection associated with HFMD and herpangina occurred in infants over one year-old. This represents the first report describing the circulation of multiple enteroviruses in Thailand.

Identification of health risks of hand, foot and mouth disease in China using the geographical detector technique

Hand, foot and mouth disease (HFMD) is a common infectious disease, causing thousands of deaths among children in China over the past two decades. Environmental risk factors such as meteorological factors, population factors and economic factors may affect the incidence of HFMD. In the current paper, we used a novel model-geographical detector technique to analyze the effect of these factors on the incidence of HFMD in China. We collected HFMD cases from 2,309 counties during May 2008 in China. The monthly cumulative incidence of HFMD was calculated for children aged 0-9 years. Potential risk factors included meteorological factors, economic factors, and population density factors. Four geographical detectors (risk detector, factor detector, ecological detector, and interaction detector) were used to analyze the effects of some potential risk factors on the incidence of HFMD in China. We found that tertiary industry and children exert more influence than first industry and middle school students on the incidence of HFMD. The interactive effect of any two risk factors increases the hazard for HFMD transmission.

Accuracy of diagnostic methods and surveillance sensitivity for human enterovirus, South Korea, 1999-2011

The epidemiology of enteroviral infection in South Korea during 1999-2011 chronicles nationwide outbreaks and changing detection and subtyping methods used over the 13-year period. Of 14,657 patients whose samples were tested, 4,762 (32.5%) samples were positive for human enterovirus (human EV); as diagnostic methods improved, the rate of positive results increased. A seasonal trend of outbreaks was documented. Genotypes enterovirus 71, echovirus 30, coxsackievirus B5, enterovirus 6, and coxsackievirus B2 were the most common genotypes identified. Accurate test results correlated clinical syndromes to enterovirus genotypes: aseptic meningitis to echovirus 30, enterovirus 6, and coxsackievirus B5; hand, foot and mouth disease to coxsackievirus A16; and hand, foot and mouth disease with neurologic complications to enterovirus 71. There are currently no treatments specific to human EV infections; surveillance of enterovirus infections such as this study provides may assist with evaluating the need to research and develop treatments for infections caused by virulent human EV genotypes.

Clinical features of coxsackievirus A4, B3 and B4 infections in children

Background

Clinical features of coxsackievirus A4 (CA4), B3 (CB3) and B4 (CB4) infections in children have not been comprehensively described.

Methods/Principal Findings

From January 2004 to June 2012, a total of 386 children with culture-proven CA4, CB3 and CB4 infections treated at Chang Gung Memorial Hospital, including 296 inpatients (CA4, 103; CB3, 131; CB4, 62) and 90 outpatients (CA4, 55; CB3, 14; CB4, 21), were included. From outpatients, only demographics were extracted and from inpatients, detailed clinical and laboratory data were collected retrospectively. The mean age was 32.1±30.2 months; male to female ratio was 1.3∶1. Children with CB3 infection were youngest (76.6% <3 years of age), and had a highest hospitalization rate (90.3%) and a longest duration of hospitalization (mean ± SD, 7.5±6.2 days). Herpangina (74.8%) was the most common presentation for children with CA4 infection, aseptic meningitis (26.7%) and young infant with fever (23.7%) for those with CB3 infection, and herpangina (32.3%) and tonsillitis/pharyngitis (27.4%) for children with CB4 infection. Almost all the inpatients had fever (97.6%). Twelve out of thirteen (92.3%) children with complications and ten of 11 children with long-term sequelae had CB3 infections. Two fatal cases were noted, one due to myocarditis with CA4 infection and CB3 were detected from the other case which had hepatic necrosis with coagulopathy. The remaining 285 children (96.3%) recovered uneventfully.

Conclusion

CA4, CB3 and CB4 infections in children had different clinical disease spectrums and involved different age groups. Though rare, severe diseases may occur, particularly caused by CB3.