Hand, foot and mouth disease in Guangdong, China, in 2013: new trends in the continuing epidemic

Detecting spatial-temporal cluster of hand foot and mouth disease in Beijing, China, 2009-2014

Background

The incidence of hand, foot, and mouth disease (HFMD) is extremely high, and has constituted a huge disease burden throughout Beijing in recent years. This study aimed to determine the spatiotemporal distribution and epidemic characteristics of HFMD.

Methods

Descriptive statistics was used to analyze the data and estimate the epidemic peaks in 2009–2014. Space–time scanning detected spatiotemporal clusters and identified high-risk locations. Global and local Moran’s I statistics were used to measure the spatial autocorrelation. Geocoding was performed in ArcGIS, based on the present address codes of the patients and the centroids of the towns. Maps were created in ArcGIS to show the geographic spread of HFMD.

Results

In total, 220,451probable cases of HFMD were reported in Beijing between January 2009 and December 2014: 12,749 (5.78 %) were laboratory confirmed, and 35 (0.02 %) were fatal. The median age of reported cases was 3.12 years (interquartile range 1.96–4.39). Coxsackievirus A16 (CV-A16), enterovirus 71 (EV-A71), and other enteroviruses accounted for 39.31, 35.36, and 25.33 % of the 12,749 confirmed cases, respectively. Many more severe cases were caused by EV-A71 (χ² = 186.41, df = 1, P < 0.001) and other enteroviruses (χ² = 156.44, df = 1, P < 0.001) than by CV-A16. A large single distinct peak occurred between May and July each year. Spatiotemporal clusters of HFMD were identified in Beijing during 2009–2014. The most likely clusters were detected and tended to move from the southwest (Fengtai and Daxing) southeastwards to Daxing and Tongzhou in 2009–2014. The incidence of HFMD was not randomly distributed, but showed global and local spatial autocorrelations.

Conclusions

There were obvious spatiotemporal clusters of HFMD in Beijing in 2009–2014. High-incidence areas mainly occurred at the junctions of urban and rural zones. More attention should be paid to the epidemiological and spatiotemporal characteristics of HFMD to establish new strategies for its control. Health issues should be especially promoted in kindergartens and at urban–rural junctions.

Characterization of Coxsackievirus A6- and Enterovirus 71-Associated Hand Foot and Mouth Disease in Beijing, China, from 2013 to 2015

BACKGROUND

Etiology surveillance of Hand Foot and Mouth disease (HFMD) in Beijing showed that Coxsackievirus A6 (CVA6) became the major pathogen of HFMD in 2013 and 2015. In order to understand the epidemiological characteristics and clinical manifestations of CVA6-associated HFMD, a comparison study among CVA6-, EV71- (Enterovirus 71), and CVA16- (Coxsackievirus A16) associated HFMD was performed.

METHODS

Epidemiological characteristics and clinical manifestations among CVA6-, EV71- and CVA16-associated mild or severe cases were compared from 2013 to 2015. VP1 gene of CVA6 and EV71 from mild cases, severe cases were sequenced, aligned, and compared with strains from 2009 to 2015 in Beijing and strains available in GenBank. Phylogenetic tree was constructed by neighbor-joining method.

RESULTS

CVA6 became the predominant causative agent of HFMD and accounted for 35.4 and 36.9% of total positive cases in 2013 and 2015, respectively. From 2013 to 2015, a total of 305 severe cases and 7 fatal cases were reported. CVA6 and EV71 were responsible for 57.5% of the severe cases. Five out six samples from fatal cases were identified as EV71. High fever, onychomadesis, and decrustation were the typical symptoms of CVA6-associated mild HFMD. CVA6-associated severe cases were characterized by high fever with shorter duration and twitch compared with EV71-associated severe cases which were characterized by poor mental condition, abnormal pupil, and vomiting. Poor mental condition, lung wet rales, abnormal pupil, and tachycardia were the most common clinical features of fatal cases. The percentage of lymphocyte in CVA6-associated cases was significantly lower than that of EV71. High percentage of lymphocyte and low percentage of neutrophils were the typical characteristics of fatal cases. VP1 sequences between CVA6- or EV71-associated mild and severe cases were highly homologous.

CONCLUSION

CVA6 became one of the major pathogens of HFMD in 2013 and 2015 in Beijing. Epidemiological characteristics, clinical manifestations of CVA6-, EV71- and CVA16-associated cases in this study enriched the definition of HFMD caused by different pathogens and shed light to accurate diagnosis, appropriate treatment and effective prevention of HFMD.

EV71 vaccine, a new tool to control outbreaks of hand, foot and mouth disease (HFMD)

On December 3rd 2015, the China Food and Drug Administration (CFDA) approved the first inactivated Enterovirus 71 (EV71) whole virus vaccine for preventing severe hand, foot and mouth disease (HFMD). As one of the few preventive vaccines for children's infectious diseases generated by the developing countries in recent years, EV71 vaccine is a blessing to children's health in China and worldwide. However, there are still a few challenges facing the worldwide use of EV71 vaccine, including the applicability against various EV71 pandemic strains in other countries, international requirements on vaccine production and quality control, standardization and harmonization on different pathogen monitoring and detecting methods, etc. In addition, the affordability of EV71 vaccine in other countries is a factor to be considered in HFMD prevention. Therefore, with EV71 vaccine commercially available, there is still a long way to go before reaching effective protection against severe HFMD after EV71 vaccines enter the market. In this paper, the bottlenecks and prospects for the wide use of EV71 vaccine after its approval are evaluated.

Epidemiological Research on Hand, Foot, and Mouth Disease in Mainland China

Hand, foot, and mouth disease (HFMD), which has led to millions of attacks and several outbreaks across the world and become more predominant in Asia-Pacific Region, especially in Mainland China, is caused by several Human Enteroviruses including new enterovirus, coxsakievirus and echovirus. In recent years, much research has focused on the epidemiological characteristics of HFMD. In this article, multiple characteristics of HFMD such as basic epidemiology, etiology and molecular epidemiology; influencing factors; detection; and surveillance are reviewed, as these can be help protect high risks groups, prevalence prediction and policy making for disease prevention.

Clinical and Etiological Characteristics of Atypical Hand-Foot-and-Mouth Disease in Children from Chongqing, China: A Retrospective Study

BACKGROUND

Hand-foot-and-mouth disease (HFMD) is a disease that had similar manifestations to chickenpox, impetigo, and measles, which is easy to misdiagnose and subsequently causes delayed therapy and subsequent epidemic. To date, no study has been conducted to report the clinical and epidemiological characteristics of atypical HFMD.

METHODS

64 children with atypical HFMD out of 887 HFMD children were recruited, stool was collected, and viral VP1 was detected.

RESULTS

The atypical HFMD accounted for 7.2% of total HFMD in the same period (64/887) and there were two peaks in its prevalence in nonepidemic seasons. Ten children (15.6%) had manifestations of neurologic involvement, of whom 4 (6.3%) were diagnosed with severe HFMD and 1 with critically severe HFMD, but all recovered smoothly. Onychomadesis and desquamation were found in 14 patients (21.9%) and 15 patients (23.4%), respectively. The most common pathogen was coxsackievirus A6 (CV-A6) which accounted for 67.2%, followed by nontypable enterovirus (26.6%), enterovirus 71 (EV-A71) (4.7%), and coxsackievirus A16 (A16) (1.5%).

CONCLUSIONS

Atypical HFMD has seasonal prevalence. The manifestations of neurologic involvement in atypical HFMD are mild and usually have a good prognosis. CV-A6 is a major pathogen causing atypical HFMD, but not a major pathogen in Chongqing, China.

Prevalence of Coxsackievirus A6 and Enterovirus 71 in Hand, Foot and Mouth Disease in Nanjing, China in 2013

BACKGROUND

Although hand, foot and mouth disease (HFMD) has been strongly associated with enterovirus 71 (EV71), coxsackievirus A16 (CVA16) and other enteroviruses, studies regarding coxsackievirus A6 (CVA6) infection in HFMD are limited. The aim of this study was to identify the major etiological agents causing HFMD in Nanjing in 2013 and explore the clinical and genetic characteristics of the prevalent enterovirus (EV) types in HFMD.

METHODS

A total of 394 throat swabs were collected from hospitalized children diagnosed with HFMD from April to July 2013. EVs were detected by reverse transcription polymerase chain reaction of 5' UTR sequences. Genotyping and phylogenetic analysis were based on VP4 sequences. Demographic and clinical data were obtained.

RESULTS

Of the specimens, 68.5% (270/394) were positive for EVs. The genotypes and detection rates were CVA6, 30.00% (81/270); EV71, 17.41% (47/270); HRV, 11.11% (30/270); CVA10, 3.33% (9/270); CVA2, 1.11% (3/270); CVA16, 0.74% (2/270); EV68, 0.37% (1/270); echovirus 6, 0.37% (1/270); echovirus 9, 0.37% (1/270), respectively. Patients infected with CVA6 displayed symptoms atypical of HFMD, including larger vesicles on their limbs and buttocks. Phylogenetic analysis revealed 2 genetically distinct CVA6 strains that circulated independently within the region. Patients infected with CVA6 were more likely to have abnormal periphery blood white blood cell and C-reactive protein levels, while EV71 was more likely to infect the central nervous system, as indicated by clinical manifestations and white blood cell analysis of cerebrospinal fluid.

CONCLUSIONS

Multiple EV genotypes contributed to HFMD in Nanjing in 2013, and CVA6 was the dominant genotype. The clinical presentation of CVA6 infection differs from that of EV71 infection in HFMD.

Fourteen types of co-circulating recombinant enterovirus were associated with hand, foot, and mouth disease in children from Wenzhou, China

BACKGROUND

Although hand, foot, and mouth disease (HFMD) is a major public concern in China, the prevalence and clinical symptoms associated with the different agents of HFMD in this country remain poorly understood.

OBJECTIVES

We investigated the clinical and molecular characteristics of enteroviruses in patients with HFMD from Wenzhou, China.

STUDY DESIGN

Patients with laboratory-confirmed HFMD admitted to the Yuying Children's Hospital in Wenzhou, China during 2013 were included in this study. Viral RNA sequences were amplified using RT-PCR, determined by sequencing, and compared by phylogenetic analysis.

RESULTS

A total of 955 clinically diagnosed HFMD cases were determined using PCR, with whole viral genomes obtained for each enterovirus type. 14 types of enterovirus belonging to two viral species were identified. Notably, Coxsackievirus A6 (CV-A6) was the most common species detected (77.8%), followed by EV-A71 (8.2%) and CV-A10 (8.1%). Phylogenetic analysis revealed multiple independent introductions of these viruses into Wenzhou. In addition, the enterovirus observed in Wenzhou had a recombinant history, with two or three recombination breakpoints. Although the illness associated with CV-A6 was milder than that of EV-A71, CV-A6 infection caused more widespread rash, larger blisters, and subsequent skin peeling and/or nail shedding.

CONCLUSION

Our study revealed the co-circulation of 14 types of enteroviruses in a single location - Wenzhou, China - with CV-A6 virus the predominant agent of HFMD. This work highlights the need to perform larger-scale surveillance to fully understand the epidemiology of enteroviruses in China and the wider Asia-Pacific region.

A novel recombinant lineage's contribution to the outbreak of coxsackievirus A6-associated hand, foot and mouth disease in Shanghai, China, 2012-2013

Since late 2012, coxsackievirus A6 (CVA6) has gradually become the predominant pathogen responsible for hand-foot-mouth disease (HFMD) in several provinces of China. A total of 626 patients diagnosed with HFMD in Shanghai, China from January 2012 to September 2013 were enrolled in this study. Of these, 292 CVA6 infected cases were subjected to clinical analyses. Whole-genome sequencing, recombination and phylogenetic analyses were also performed. A recombinant CVA6 monophyletic lineage was found during an outbreak of CVA6-associated HFMDs in Shanghai, China in November 2012, and accounted for 21.9% (64/292) of the CVA6 strains during the study period. Recombination analyses showed that the 2C gene of the novel CVA6 virus was probably derived from a coxsackievirus A4 (CVA4) strain circulating in the population. Clinical observation showed that this recombinant CVA6 virus led to a more generalized rash than did the non-recombinant CVA6 virus. This newly emerged CVA6 lineage was associated with a considerable proportion of HFMD cases from 2012 to 2013 in Shanghai, and poses a potential threat to public health.

Is a multivalent hand, foot, and mouth disease vaccine feasible?

Enterovirus A infections are the primary cause of hand, foot and mouth disease (HFMD) in infants and young children. Although enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are the predominant causes of HFMD epidemics worldwide, EV-A71 has emerged as a major neurovirulent virus responsible for severe neurological complications and fatal outcomes. HFMD is a serious health threat and economic burden across the Asia-Pacific region. Inactivated EV-A71 vaccines have elicited protection against EV-A71 but not against CV-A16 infections in large efficacy trials. The current development of a bivalent inactivated EV-A71/CV-A16 vaccine is the next step toward that of multivalent HFMD vaccines. These vaccines should ultimately include other prevalent pathogenic coxsackieviruses A (CV-A6 and CV-A10), coxsackieviruses B (B3 and B5) and echovirus 30 that often co-circulate during HFMD epidemics and can cause severe HFMD, aseptic meningitis and acute viral myocarditis. The prospect and challenges for the development of such multivalent vaccines are discussed.

The Epidemiological Study of Coxsackievirus A6 revealing Hand, Foot and Mouth Disease Epidemic patterns in Guangdong, China

Enterovirus A71 (EVA71) and Coxsackievirus A16 (CVA16) are regarded as the two major causative pathogens in hand, foot and mouth disease (HFMD) epidemics. However, CVA6, previously largely ignored, became the predominant pathogen in China in 2013. In this study, we describe the epidemiological trendsofCVA6 during the annual HFMD outbreaks from 2008 to 2013 in Guangdong, China. The study results show that CVA6 has been one of three major causative agents of HFMD epidemics since 2009. The periodic rotation and dominance of the three pathogens, EVA71, CVA16 and CVA6, may have contributed to the continuously increasing HFMD epidemics. Moreover, phylogenetic analysis of the VP1 gene shows that major circulating CVA6 strains collected from 2009 to 2013 are distinct from the earlier strains collected before 2009. In conclusion, the discovery from this research investigating epidemiological trends of CVA6 from 2008 to 2013 explains the possible pattern of the continuous HFMD epidemic in China. The etiological change pattern also highlights the need for improvement for pathogen surveillance and vaccine strategies for HFMD control in China.

Characterization of severe hand, foot, and mouth disease in Shenzhen, China, 2009-2013

Hand, foot, and mouth disease (HFMD) is caused by human enteroviruses, especially by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). Patients infected with different enteroviruses show varied clinical symptoms. The aim of this study was to determine whether the etiological spectrum of mild and severe HFMD changed, and the association between pathogens and clinical features. From 2009 to 2013, a total of 2,299 stool or rectal specimens were collected with corresponding patient data. A dynamic view of the etiological spectrum of mild and severe HFMD in Shenzhen city of China was provided. EV71 accounted for the majority proportion of severe HFMD cases and fatalities during 2009-2013. CA16 and EV71 were gradually replaced by coxsackievirus A6 (CA6) as the most common serotype for mild HFMD since 2010. Myoclonic jerk and vomiting were the most frequent severe symptoms. Nervous system complications, including aseptic encephalitis and aseptic meningitis were observed mainly in patients infected by EV71. Among EV71, CA16, CA6, and CA10 infection, fever and pharyngalgia were more likely to develop, vesicles on the hand, foot, elbow, knee and buttock were less likely to develop in patients infected with CA10. Vesicles on the mouth more frequently occurred in the patients with CA6, but less in the patient with EV71. Associations between diverse enterovirus serotypes and various clinical features were discovered in the present study, which may offer further insight into early detection, diagnosis and treatment of HFMD.

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

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

Comparative epidemiology and virology of fatal and nonfatal cases of hand, foot and mouth disease in mainland China from 2008 to 2014

This study aimed to analyze the epidemiology and virology of fatal and nonfatal hand, foot, and mouth disease (HFMD) cases in Mainland China. A total of 10,714,237 survivors and 3046 deaths were reported from 2008 to 2014 June, with a case fatality rate of 0.03%. The morbidity of the survivors increased from 37.6/100,000 in 2008 to 139.6/100,000 in 2013 and peaked in 2012 at 166.8/100,000. However, the mortality varied around 0.03-0.04/100,000 across the time. Most of the survivors were distributed in the southern and eastern China, predominantly in the Guangxi and Hainan Province, whereas deaths were dominant in southern (Guangxi) and southwestern (Guizhou) China. The two groups showed similar seasonal fluctuations from 2008 to 2014, peaking in spring and early summer. Of the total cases, 93.97% were children less than 5 years of age, with those ≤ 2 years old accounting for 60.08% versus 84.02% in the survivor and death groups, respectively. Boys were at higher risk of infection than girls in both groups. Five years of virological surveillance showed that 43.73%, 22.04%, and 34.22% of HFMD cases were due to EV71, CoxA16 and other enteroviruses, respectively. EV71 was encountered in most deaths, with no substantial effect of age, gender, month, and year on incidence. Subgenotype C4a was the prevalent EV71 strain in Mainland China, with no significant difference in the VP1 gene related to virulence between the two groups. In conclusion, based on the largest population study, fatal and nonfatal HFMD cases, mainly caused by C4a of EV71, are circulating in Mainland China with a low-cause fatality rate.

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 profiles of hand, foot, and mouth disease, including meteorological factors, in Suzhou, China

The purpose of this study was to examine the epidemiological profiles of hand, foot, and mouth disease (HFMD) activity in Suzhou, China, and the relationship between meteorological factors and enterovirus71 (EV71) and coxsackievirus A16 (CoxA16) infection. Children < 14 years old with probable HFMD at Soochow University Affiliated Children's Hospital were enrolled during January 2008 to December 2013. Samples from hospitalized children with HFMD were collected and tested using real-time reverse transcription PCR. Correlations between probable HFMD, laboratory-confirmed HFMD, and meteorological factors were analyzed using bivariate correlation, stepwise regression and time series analysis. A total of 29,530 probable cases were diagnosed with HFMD, and 1090 hospitalized cases were confirmed in the laboratory. The median age of individuals with HFMD was 28.6 months (interquartile range, 18-46.9 months), and the incidence was highest in children aged 12-36 months. Children infected with other enteroviruses were younger than those infected with EV71 and CoxA16. Mean temperature and total rainfall were strongly correlated with probable HFMD. In terms of the specific pathogen, only EV71 cases were associated with mean temperature during the study period of 2012-2013. Based on a simple seasonal model with a good fit, a seasonal pattern of HFMD activity could be predicted. This study provides quantitative evidence that probable HFMD was associated with mean temperature and total rainfall. Furthermore, a seasonal model could be used as an early and reliable monitoring system to predict seasonal pattern of HFMD in Suzhou, China.

The role of enterovirus 71 and coxsackievirus A strains in a large outbreak of hand, foot, and mouth disease in 2012 in Changsha, China

BACKGROUND

During 2012, Changsha experienced a large outbreak of hand, foot, and mouth disease (HFMD), resulting in 25,438 cases, including 42 severe cases and eight deaths.

METHODS

Seven hundred and forty-six clinical specimens were collected from hospital-based surveillance for HFMD in 2012. The detection and genotyping of enterovirus were performed by real-time RT-PCR and sequencing of the VP1 regions; phylogenetic analysis was performed based on the VP1 sequences.

RESULTS

A total of 545 (73.1%) enterovirus-positive samples were identified, with the most frequently presenting serotype being enterovirus 71 (EV-71; n=364, 66.8%), followed by coxsackievirus A16 (CV-A16; n=84, 15.4%), CV-A6 (n=22, 4.0%), and CV-A10 (n=19, 3.5%). Most of the affected patients were children aged ≤5 years (n=524, 96.1%). EV-71 was the major pathogen in the severe and fatal cases (n=22, 78.6%). Phylogenetic analysis of VP1 gene sequences showed the EV-71 isolates to belong to subgenotype C4a, and the CV-A16 isolates to belong to subgenotype B1. The Changsha CV-A6 and CV-A10 circulating strains were homologous to strains circulating in other areas of mainland China.

CONCLUSIONS

Our results demonstrate that EV-71 was the primary causative agent responsible for the HFMD outbreak in Changsha in 2012, and the co-circulation of other coxsackievirus A strains posed a potential risk to public health.