Epidemiology of 45,616 suspect cases of Hand, Foot and Mouth Disease in Chongqing, China, 2011-2015

Factors related to the mortality risk of severe hand, foot, and mouth diseases (HFMD): a 5-year hospital-based survey in Guangxi, Southern China

BACKGROUND

To understand the factors influencing clinical outcomes of severe hand, foot, and mouth diseases (HFMD), and to provide scientific evidence for reducing the mortality risk of severe HFMD.

METHODS

From 2014 to 2018, children diagnosed with severe HFMD cases in Guangxi, China, were enrolled in this hospital-based study. The epidemiological data obtained through face-to-face interviews with the parents and guardians. Univariate and multivariate logistics regression models were used to analyze the factors influencing the clinical outcomes of severe HFMD. The impact of the EV-A71 vaccination on inpatient mortality was analyzed by a comparison approach.

RESULTS

A total of 1565 severe HFMD cases were enrolled in this survey, including 1474 (94.19%) survival cases and 91 (5.81%) death cases. The multivariate logistic analysis demonstrated that HFMD history of playmates in the last three months, first visit to the village hospital, time from the first visit to admission less than two days, no correct diagnosis for HFMD at the first visit, and having no rash symptoms were the independent risk factors for severe HFMD cases (all p < 0.05). While EV-A71 vaccination was a protective factor (p < 0.05). The EV-A71 vaccination group versus the non-vaccination group showed 2.23% of death in the vaccination group and 7.24% of death in the non-vaccination group. The EV-A71 vaccination protected 70.80% of the death of severe HFMD cases, with an effective index of 4.79.

CONCLUSIONS

The mortality risk of severe HFMD in Guangxi was related to playmates had HFMD history in last 3 months, hospital grade, EV-A71 vaccination, patients visit hospital previously, and rash symptom. EV-A71 vaccination can significantly reduce mortality among severe HFMD. The findings are of great significance for the effective prevention and control of HFMD in Guangxi, southern China.

Coxsackievirus A6 was the most common enterovirus serotype causing hand, foot, and mouth disease in Shiyan City, central China

BACKGROUND

Hand, foot, and mouth disease (HFMD) has become one of the most common infectious diseases in China. Before 2016, the primary causal serotypes were enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). Following the introduction of EV-A71 vaccines in China since 2016, the situation could change. CV-A6 has recently replaced EV-A71 and CV-A16 in some areas of China. However, the epidemiological characteristics of central China remain unknown.

AIM

To investigate the clinical symptoms and pathogen spectrum of HFMD in Shiyan City, central China, in recent years.

METHODS

The epidemiological, clinical, and laboratory data from HFMD cases reported to the Shiyan Center for Disease Control and Prevention between January 2016 and December 2020 were analyzed. 196 throat swab specimens were collected from hospitalized HFMD patients between January 2018 and December 2020. To detect and genotype enteroviruses, real-time reverse transcription-polymerase chain reaction and sequencing of the 5'-untranslated region were used. In Shiyan, 168 laboratory-confirmed HFMD cases were studied using a logistic regression model to determine the effect of predominant enterovirus serotypes. Based on the logistic regression model, the least absolute shrinkage and selection operator model was used to analyze the correlation between CV-A6 infection and various clinical characteristics in HFMD patients in Shiyan.

RESULTS

From 2016 to 2020, 35840 HFMD cases were reported in Shiyan. The number of cases decreased by 48.4% from 2016 to 2017. Approximately 1.58-fold increases were found in 2018 and 2019 when compared to the previous year, respectively. In 2020, a decrease of about 85.5% was reported when compared to 2019. The most common serotypes shifted from EV-A71 and CV-A16 (about 60%-80% in 2016 and 2018) to others (more than 80.0% in 2017, 2019, and 2020). EV-A71 lost its dominance in 2017 in Shiyan. Among 196 confirmed HFMD cases, 85.7% tested positive for enterovirus, with CV-A6 being the most common serotype (121/168, 72.0%). The positive rates for CV-A16 and CV-A10 were 4.8% and 3.0%, respectively. There was no EV-A71 discovered. Infection with CV-A6 was linked to fever, myocardial damage, increased creatine kinase MB isoenzyme, and lactate dehydrogenase levels.

CONCLUSION

CV-A6 was the most common enterovirus serotype in Shiyan City, replacing EV-A71 and CV-A16 as the HFMD pathogen. Developing vaccines against CV-A6 or multiple pathogens, as well as rising CV-A6 surveillance, will help prevent HFMD in central China.

Genome-wide population structure inferences of human coxsackievirus-A; insights the genotypes diversity and evolution

Coxsackievirus-A (CV-A) is a causative agent of Hand Foot Mouth Disease (HFMD) worldwide. It belongs to the Human Enterovirus genus of the family Picornaviridae. The genomics data availability of CV-A samples, isolated from human host across different continental regions, provide an excellent opportunity to study its genetic composition, diversity, and evolutionary events. The complete genome sequences of 424 CV-A isolates were analyzed through a model-based population genetic approach implemented in the STRUCTURE program. Twelve genetically distinct sub-populations were identified for CV-A isolates with a marked Fst distinction of 0.76991 (P-value = 0.00000). Besides, genetically admixed strains were characterized in the G-Id, G-IIIb clusters constituted by the CV-A12 and CV-A6 enterovirus serotypes. The serotypes depicted inter/intra-genotype recombination and episodic positive selection signatures in the structural and non-structural protein-coding regions. The observed genetic composition of CV-A samples was also deduced by the phylogenetic tree analyses, where a uniform genetic structure was inferred for most of the CV-A genotypes. However, the CV-A6 serotype samples genetically stratified into three sub-populations that may lead to the emergence of new lineages in future. These informations may implicate in planning the effective strategies to combat the coxsackievirus-A-mediated infection.

Epidemiological characteristics and spatiotemporal analysis of hand-foot-mouth diseases from 2010 to 2019 in Zibo city, Shandong, China

Background

Hand-foot-mouth disease (HFMD) is a global public health issues, especially in China. It has threat the health of children under 5 years old. The early recognition of high-risk districts and understanding of epidemic characteristics can facilitate health sectors to prevent the occurrence of HFMD effectively.

Methods

Descriptive analysis was used to summarize epidemic characteristics, and the spatial autocorrelation analysis and space-time scan analysis were utilized to explore distribution pattern of HFMD and identify hot spots with statistical significance. The result was presented in ArcMap.

Results

A total of 52,095 HFMD cases were collected in Zibo city from 1 Jan 2010 to 31 Dec 2019. The annual average incidence was 129.72/100,000. The distribution of HFMD was a unimodal trend, with peak from April to September. The most susceptible age group was children under 5 years old (92.46%), and the male-to-female ratio is 1.60: 1. The main clusters were identified in Zhangdian District from 12 April 2010 to 18 September 2012. Spatial autocorrelation analysis showed that the global spatial correlation in Zibo were no statistical significance, except in 2012, 2014, 2015, 2016 and 2018. Cold spots were gathered in Boshan county and Linzi district, while hot spots only in Zhangdian District in 2018, but other years were no significance.

Conclusion

Hot spots mainly concentrated in the central and surrounding city of Zibo city. We suggest that imminent public health planning and resource allocation should be focused within those areas.

Epidemical and etiological study on hand, foot and mouth disease following EV-A71 vaccination in Xiangyang, China

Coxsackievirus A6 (CV-A6) and Coxsackievirus A10 (CV-A10) have been emerging as the prevailing serotypes and overtaking Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) in most areas as main pathogens of hand, foot and mouth disease (HFMD) in China since 2013. To investigate whole etiological spectrum following EV-A71 vaccination of approximate 40,000 infants and young children in Xiangyang, enteroviruses were serotyped in 4415 HFMD cases from October 2016 to December 2017 using Real Time and conventional PCR and cell cultures. Of the typeable 3201 specimen, CV-A6 was the predominant serotype followed by CV-A16, CV-A10, CV-A5, CV-A2 and EV-A71 with proportions of 59.54%, 15.31%, 11.56%, 4.56%, 3.78% and 3.03%, respectively. Other 12 minor serotypes were also detected. The results demonstrated that six major serotypes of enteroviruses were co-circulating, including newly emerged CV-A2 and CV-A5. A dramatic decrease of EV-A71 cases was observed, whereas the total cases remained high. Multivalent vaccines against major serotypes are urgently needed for control of HFMD.

Onychomadesis and potential association with HFMD outbreak in a kindergarten in Hubei province, China, 2017

BACKGROUND

In 2017, an outbreak of onychomadesis occurred in kindergarten H, Hubei province, China. We investigated the field to learn about the magnitude and reason of the outbreak.

METHODS

The case definition was that a child with onychomadesis or transverse ridging (Beau's line) in fingernails and toenails without previous traumatic or systemic disease in kindergarten H from Sep. 1st to Nov. 30th, 2017. A retrospective cohort study was carried out to analyze the epidemiological relationship between onychomadesis and the hand-foot-mouth disease (HFMD) in Primary Class #2, kindergarten H. We also performed a serological survey for neutralizing antibodies against coxsackie virus A6 (CVA6), coxsackie virus A10 (CVA10) among 15 cases and six healthy children in the kindergarten. Meanwhile, some children were carried out with routine blood, fungal microscopic and microelement tests. Indoor environment examinations had been done for all classes.

RESULTS

A total of 20 cases were identified in Kindergarten H. Seventy-five percent (15/20) cases occurred in Primary Class #2. Fifty-five percent of the cases (11/20) had suffered from HFMD within two months. The median time between onychomadesis and HFMD was 45 days (ranging from 31 to 58 days). A retrospective cohort study in Primary Class #2 showed the attack rate was 90.0% among 10 children who suffered from HFMD in the past two months compared to 30.0% among 20 children who didn't (Rate Ratio [RR] =3.0, 95% Confidence Interval [CI] =1.5-6.0). The positive rates of neutralizing antibodies were 66.7% for CVA6 and 26.7% for CVA10 in tested cases. The result of routine blood, fungal microscopic, microelements tests were normal in cases. The indicators of environment were within the normal range.

CONCLUSION

The results of this study suggested that the outbreak of onychomadesis in Hubei province was probably associated with HFMD epidemic within two months.

The epidemic characteristics and spatial autocorrelation analysis of hand, foot and mouth disease from 2010 to 2015 in Shantou, Guangdong, China

BACKGROUND

Hand, foot and mouth disease (HFMD) is the highest incidence of infectious diseases in China. Shantou is one of the most infected cities. Therefore, it is necessary for us to understand the epidemic characteristics and distribution trend of HFMD in Shantou. The purpose of this study is to investigate the spatial epidemiological characteristics of HFMD and analyse its spatial autocorrelation.

METHOD

We collated and summarised the data of HFMD in Shantou from 2010 to 2015. SaTScan software and Moran's I were used to analyse the spatial correlation of HFMD, and the results were presented in ArcMap.

RESULTS

The distribution of HFMD in Shantou was of a seasonal trend, mainly concentrating during May and June. Children under 5-years-old were the main group of cases of HFMD, accounting for 92.46%. The proportion of infected children, especially those aged zero to 1, was the largest in each year, accounting for 45.62%, meaning that smaller children were more susceptible to HFMD. The number of male patients with HFMD was greater than that of females (1.78:1, male: female). With regard to the potential impact of patients' living style on the incidence rate of HFMD, this study revealed that scattered children were the dominant infected population, accounting for as much 84.49% of cases. The incidence of HFMD was unevenly distributed among streets. The incidence interval of streets was in a range of 13.76/100,000 to 1135.19/100,000. Spatial autocorrelation analysis showed that there was no global spatial correlation in Shantou, except in 2013. The results of local spatial autocorrelation analysis showed that H-H correlation existed in the high incidence local area of Shantou.

CONCLUSIONS

The incidence of HFMD across the various streets in Shantou not only varied widely but also represented local autocorrelation. Attention, as well as prevention and control measures, should be focused on those high-incidence areas, such as the Queshi street, Zhuchi street and Xinjin street.

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

Hand, foot, and mouth disease (HFMD) is well recognized as one of the major threats to children’s health globally. The increasing complexity of the etiology of HFMD still challenges disease control in China. There is little surveillance of the molecular epidemiological characteristics of the enteroviruses (EVs) that cause HFMD in Neijiang city or the Sichuan Basin area in Southwest China. In this study, demographic and epidemiological information for 14,928 probable HFMD cases was extracted and analyzed to describe the epidemic features of HFMD in Neijiang city from Jan 2010 to Dec 2017. The swab samples of select probable HFMD cases from 2012 to 2017 were tested by reverse transcription (RT) real-time PCR to identify the serotype distribution of EVs, and 110 randomly selected RT-real-time PCR positive samples were then amplified and analyzed for the VP1 or VP4 regions of EVs to further analyze the phylogenetic characteristics of the circulating strains in this area. The eight-year average annual incidence was 49.82 per 100,000 in Neijiang. The incidence rates varied between 19.51 and 70.73 per 100,000, demonstrating peaks of incidence in even-number years (2012, 2014 and 2016). The median age of the probable cases was 27 months and the interquartile range (25^th to 75^th percentile) of ages for the probable HFMD cases was between 14 and 42 months. The male-to-female ratio of the probable HFMD cases was 1.47:1, and scattered children were the major population classification (81.7%). Two epidemic peaks were observed: one major peak between April and July and the other lesser peak between October and December. Of 6513 probable cases tested with RT-real-time PCR, 4015 (61.6%) were positive for enterovirus with the serotype distribution as follows: EV71+, 30.1% (n = 1210); CV-A16+, 28.7% (n = 1154) and a sole pan-enterovirus+, 41.1% (n = 1651). A total of 91 cases (82.7%, 91/110) were successfully amplified and underwent phylogenetic analysis: all EV71+ cases were C4a serotype (n = 23/30); all CV-A16+ cases were B2b serotype (n = 24/30); of 42 sole pan-enterovirus+ samples, 20 were CV-A6, 14 were CV-A10 and the rest within this group were CV-A4 (n = 4), CV-A8 (n = 2), CV-A9 (n = 1) and CV-B3 (n = 1). Our findings provide important evidence that aids the improvement of strategies for vaccination against HFMD and comprehensive disease control in China.

Identification of previously untypable RD cell line isolates and detection of EV-A71 genotype C1 in a child with AFP in Nigeria

We previously attempted to identify 96 nonpolio enteroviruses (EVs) recovered in RD cell culture from children <15 years with acute flaccid paralysis in Nigeria. We succeeded in identifying 69 of the isolates. Here, we describe an attempt to identify the remaining 27 isolates. Twenty-six (the 27th isolate was exhausted) isolates/samples that could not be typed previously were further analyzed. All were subjected to RNA extraction, cDNA synthesis, enterovirus 5'-UTR-VP2 PCR assay and a modified VP1 snPCR assay. Both the 5'-UTR-VP2 and VP1 amplicons were sequenced, isolates identified and subjected to phylogenetic analysis.Twenty of the 26 samples analyzed were identified. Altogether, 23 (three samples had co-infection) EV strains were recovered. These belong to 11 EV (one EVA, nine EVB and one EVC) types which were EVA71 genotype C1 (1 strain), CVB3 (7 strains), CVB5 (1 strain), E5 (2 strain), E11 (3 strains), E13 (2 strain), E19 (1 strain), E20 (1 strain), E24 (2 strains), EVB75 (1 strain) and EVC99 (2 strains). Of the 11 EV types, the 5'-UTR-VP2 assay identified seven while the VP1 assay identified 10. Both assays simultaneously detected 7 of the 11 EV types identified in this study with 100% congruence. We successfully identified 20 of 26 samples that were previously untypable. We also provided evidence that suggests a clade of EVA71 genotype C1 might have been circulating in sub-Saharan Africa since 2008. Finally, we showed that the 5'-UTR -VP2 assay might be as valuable as the VP1 assay in EV identification.

Characterization of an inactivated whole-virus bivalent vaccine that induces balanced protective immunity against coxsackievirus A6 and A10 in mice

Coxsackievirus A6 (CVA6) and CVA10 are two of the major pathogens associated with hand, foot and mouth disease (HFMD) in children. The majority of CVA6 and CVA10 infections result in mild, self-limiting episodes (fever and herpangina) in pediatric populations; however, in some cases, can proceed to severe neurological disease and death. Efforts to mitigate viral transmission to decrease the morbidity and mortality associated with infection would be greatly strengthened by the availability of an efficacious CVA6 and CVA10 bivalent vaccine. Here we report the immunogenicity and protective efficacy of a bivalent combination vaccine comprised of formaldehyde-inactivated, whole-virus CVA6 and CVA10. We demonstrate that subcutaneous delivery of the bivalent vaccine can induce antigen-specific systemic immune responses, particularly the induction of polyfunctional T cells, which elicit active immunization to achieve a protection rate of >80% in the infected neonatal mice. Furthermore, passive transfer of the antisera from vaccinated mice potently protected recipient mice against CVA6 and CVA10 challenge. Importantly, the bivalent vaccine could induce high levels of IgG and neutralizing antibodies in adult female mice and the maternal antibody transmitted to the recipient mice played an important role in controlling homotypic and heterotypic CVA6 and CVA10 infections and viral replication in vivo. Collectively, these findings indicate that there is no immunological interference between the two antigens with respect to their ability to induce virus-specific immune responses, and thus provides proof-of-concept for further development of multivalent vaccines for broad protection against HFMD.

Effects of relative humidity on childhood hand, foot, and mouth disease reinfection in Hefei, China

BACKGROUND

In recent years, hand, foot, and mouth disease (HFMD) has become a major public health issue in China, and its reinfection rate has been high. Numerous studies have examined the effects of meteorological factors involved in HFMD infection. However, no study has investigated the effects on HFMD reinfection. The present study analyzed the relationship between relative humidity and HFMD reinfection.

METHODS

We employed a distributed lag nonlinear model to evaluate the relationship between relative humidity and childhood HFMD reinfection in Hefei, China during 2011-2016. This model controlled confounding factors, including seasonality, long-term trend, day of the week, precipitation, and mean temperature.

RESULTS

Childhood HFMD reinfection cases occurred mainly from April to July, and the second peak occurred from October to December. A statistically significant association was observed between relative humidity and HFMD reinfection with delayed effects. The adverse effect of high relative humidity (>75%) appeared later than those of low relative humidity (<75%). Moreover, the highest relative risk (RR 1.08, 95% CI 1.04-1.13) occurred when the relative humidity was 100% and had an 8-day lag. Given the differences between gender and age groups, the effects of extremely high relative humidity on females and those aged ≥4years were higher than those of other groups and caused the highest cumulative relative risks at lag 0-9 or 0-10days (Female: RR 2.00, 95% CI 1.23-3.26; Male: RR 1.55, 95% CI 1.04-2.30; Aged ≥4years: RR 2.31, 95% CI 1.27-4.18; Aged <4years: RR 1.51, 95% CI 1.04-2.20).

CONCLUSION

High and low relative humidity were found to cause the elevated risks of HFMD reinfection, and the highest risk was observed at extremely high relative humidity. Early warning systems should be built for the protection of susceptible populations, particularly females and children aged ≥4years.

Abundance of enterovirus C in RD-L20B cell culture-negative stool samples from acute flaccid paralysis cases in Nigeria is geographically defined

PURPOSE

We recently showed that enteroviruses (EVs) andenterovirus species C (EV-C) in particular were abundant in faecal samples from children who had been diagnosed with acute flaccid paralysis (AFP) in Nigeria but declared to be EV-free by the RD-L20B cell culture-based algorithm. In this study, we investigated whether this observed preponderance of EVs (and EV-Cs) in such samples varies by geographical region.

METHODOLOGY

One hundred and eight samples (i.e. 54 paired stool suspensions from 54 AFP cases) that had previously been confirmed to be negative for EVs by the WHO-recommended RD-L20B cell culture-based algorithm were analysed. The 108 samples were made into 54 pools (27 each from North-West and South-South Nigeria). All were subjected to RNA extraction, cDNA synthesis and the WHO-recommended semi-nested PCR assay and its modifications. All of the amplicons were sequenced, and the enteroviruses identified, using the enterovirus genotyping tool and phylogenetic analysis.

RESULTS

EVs were detected in 16 (29.63 %) of the 54 samples that were screened and successfully identified in 14 (25.93 %). Of these, 10 were from North-West and 4 were from South-South Nigeria. One (7.14 %), 2 (14.29 %) and 11 (78.57 %) of the strains detected were EV-A, EV-B and EV-C, respectively. The 10 strains from North-West Nigeria included 7 EV types, namely CV-A10, E29, CV-A13, CV-A17, CV-A19, CV-A24 and EV-C99. The four EV types recovered from South-South Nigeria were E31, CV-A1, EV-C99 and EV-C116.

CONCLUSION

The results of this study showed that the presence of EVs and consequently EV-Cs in AFP samples declared to be EV-free by the RD-L20B cell culture-based algorithm varies by geographical region in Nigeria.

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.