Seroprevalence of Enterovirus A71 and Coxsackievirus A16 in Healthy People in Shandong Province, China.

BACKGROUND: Hand, foot, and mouth disease has become very common in mainland of China in recent years, and enterovirus A71 and coxsackievirus A16 are its major etiologic factors. Here we investigated the seroprevalence of enterovirus A71 and coxsackievirus A16 based on a large group of healthy individuals in Shandong province, China. METHODS: A total of 1378 healthy individuals were tested for serum neutralizing antibodies against enterovirus A71 and coxsackievirus A16 using a micro neutralization test. RESULTS: The overall seroprevalence of enterovirus A71 neutralizing antibodies was 74.75%. It increased significantly from 48.84% in children aged 0-1 years old to 88.64% in those aged 20-29 years (p < 0.01) and decreased to 85.71% in adults > 40 years old with a significant gender-specific difference (p < 0.01). The overall coxsackievirus A16 antibody prevalence was 71.77%. It increased significantly from 39.53% in children aged 0-1 years to 80.68% in those aged 10-19 years (p < 0.01) and decreased to 75.63% in adults >40 years without a gender-specific difference. Nearly 50% of the children <1 year were susceptible to enterovirus A71 infection versus 40% to coxsackievirus A16 infection. Sample collection time and place also played a role in the enterovirus A71 and coxsackievirus A16 positive rates. The overall rates in January were significantly lower than those in April and August (p < 0.01); enterovirus A71 positive rates in Jinan city (capital city of Shandong province) were lower than those in Jining city and Zibo city (p < 0.05); and oxsackievirus A16 positive rates in Jining city were significantly higher than those in Jinan city and Zibo city (p < 0.01). CONCLUSION: There were significant differences among age groups, locations, and time points in the seroprevalence rates of enterovirus A71 and coxsackievirus A16 neutralizing antibodies in healthy people in Shandong province.

[Epidemiology of hand, foot, and mouth disease and genetic characterization of enterovirus A71: a survey from 2007 to 2012 in Linyi of Shandong Province, China].

To investigate the epidemiology of hand, foot, and mouth disease (HFMD) and the genetic characteristics of enterovirus A71 (EV-A71) in Linyi of Shandong Province, China during 2007-2012. The number of reported HFMD cases were obtained from the National Notifiable Disease Reporting System (NNDRS) were analyzed by descriptive epidemiology method; the VP1 region of EV-A71 isolated from HFMD patients in Linyi was amplified and sequenced. Finally, the genetic variability and phylogenecity of VP1 sequences of EV-A71 were analyzed by MEGA 5.0. The results showed that HFMD incidence was reported in each year from 2007 to 2012 in Linyi, and the highest incidence and mortality were reported in 2009, when there were total 14697 cases and 9 of death. The reported incidence was 140.28/100000, and the mortality was 0.086/100000. The peak incidence usually occurred between April and July, and the summit occurred in May. Scattered children accounted for 77.37%-92.00% of all cases. The peak age was 2.5 years during 2007-2009 and 1.5 years during 2010-2012. A total of 1365 laboratory-confirmed HFMD cases were reported in the 6 consecutive years, accounting for 2.98% of the gross number. Among these reports, the ratio of EV-A71 was 44.18%, and the ratio of coxsackievirus A16 (CVA16) was 46.59%. All EV-A71 strains isolated in Linyi during 2007-2012 belonged to the C4a evolutionary branch of C4 genotype. In conclusion, HFMD outbreaks occurred every year in Linyi during 2007-2012. Incidence varied significantly among different counties. The peak incidence in each year lasted from April to July. Most of the patients were children under 3 years of age, and scattered children took the highest proportion. Co-circulation of EV-A71 and CVA16 was the major cause of HFMD in each year. Since the first report of HFMD prevalence caused by EV-A71 (C4a) in 2007, the virus has been prevalent continuously in Linyi for 6 years.

[Epidemiology and etiology of hand-foot-and-mouth disease in Hainan, 2010].

To reveal the epidemiological and pathogenic characteristics of Hand-foot-and-mouth disease (HFMD) in Hainan province in 2010, epidemiology data of HFMD reporting cases were analyzed, clinical specimens from 1346 HFMD cases were collected for enterovirus (EV) detection. Viral isolation was performed for EV nucleic acid positive samples. Complete VP1 encoding region of EV71 were sequenced and analyzed with Sequencher (version 5.0) and MEGA software (version 5.0). The epidemiology data showed that all 18 prefectures in Hainan had reporting cases during 2010, with higher incidence in the northeast; and the children less than 4 years old accounted for the majority of the suffered; the epidemic reached peak during September to October, which was different from other Provinces in China. The laboratory results indicated that EV71 and CA16 were identified as the major causative pathogens in Hainan in 2010, however, EV71 infection was absolutely dominant among severe and fatal cases. In addition, some HFMD cases were identified associated with other serotypes of EV infections. Molecular epidemiological analysis showed that all the EV71 strains belonged to C4a evolutionary branch, which is the dominant evolutionary branch in China in recent years, and at least three transmission chains existed. This study has an important information in clarifying the characteristics of epidemics and transmission of HFMD in Hainan, and to provide the guidance for HFMD prevention and control in the future.

[Rash and fever illness caused by herpes simplex virus type 1 needs to be distinguished from hand, foot and mouth disease].

An epidemic of rash and fever illnesses suspected of hand, foot and mouth disease (HFMD) occurred in Gansu Province of China in 2008, laboratory tests were performed in order to identify the pathogen that caused this epidemic. Eight clinical specimens collected from the 4 patients (each patient has throat swab and herpes fluid specimens) with rash and febrile illness, were inoculated onto RD and HEp-2 cells for virus isolation, and the viral nucleic acid was then extracted with the positive virus isolates, the dual-channel real-time reverse transcript-polymerase chain reaction (RT-PCR) was performed to detect the nucleic acid of human enterovirus (HEV) in the viral isolates at the same time. For the viral isolates with the negative results of HEV, a sequence independent single primer amplification technique (SISPA) was used for "unknown pathogen" identification. Totally, 6 viral isolates were identified as herpes simplex virus type 1 (HSV-1). Comprehensive analyses results of the clinical manifestations of the patients, epidemiological findings and laboratory test indicated that this epidemic of rash and febrile illness was caused by HSV-1. The differences among the gG region of 6 HSV-1 isolates at nucleotide level and amino acid level were all small, and the identities were up to 98. 8% and 97.9%, respectively, showing that this outbreak was caused by only one viral transmission chain of HSV-1. HSV-1 and other viruses that cause rash and febrile illnesses need differential diagnosis with HFMD. The etiology of rash and febrile illness is sometimes difficult to distinguish from the clinical symptoms and epidemiological data, the laboratory diagnosis is therefore critical.

[Identification and genetic characteristics of five non-polio enteroviruses (NPEVs) multiplicated on L20B cell line].

OBJECTIVE: To identify and describe the genetic characteristics of non-polio enteroviruses (NPEVs) which could multiplicated on L20B cell line, and discuss the impact to isolation rate of polioviruses. METHODS: 5 L20B positive isolates were collected from stool samples of patient with acute flaccid paralysis (AFP) and health children in Guangxi Zhuang autonomous region and Ningxia Hui autonomous region. These isolates were analysed using VP4 nucleotide sequencing method. The completed VP, coding regions were amplified and sequenced. Finally, phylogenetic tree were constructed base on completed VP1 coding regions sequences of these L20B positive isolates and those downloaded form GenBank database. RESULTS: The 5 NPEVs were all identified as coxsackieviruses group A (CVA). Among them, 1 was identified as CVA4, 1 was identified as CVA8 and 3 were identified as CVA10, and all of them belonged to human enterovirus species A (HEV-A). Nucleotide homology analysis and phylogenetic analysis base on completed VP1 coding regions sequences showed that all these 3 serotypes of NPEVs clustered independently, and they were all native circulated viruses in mainland China. CONCLUSIONS: 5 NPEVs in this study belonged to HEV-A, covered 3 serotypes, CVA4, CVA8 and CVA10. Due to the high sensitivity of primarily inoculation of poliovirus onto L20B cell, the isolation rate of polioviruses could not be affected so much. Hand, foot, and mouth disease (HFMD) outbreaks in mainland China in recent years, and it was found that HEV-A is also pathogen of HFMD. Identification of these viruses have current significance to differential diagnosis of poliovirus infection and HFMD control and prevention.

[Genetic characterization of coxsackievirus A16 isolated in Ningxia Hui Municipality in 2008].

OBJECTIVE: To study the genetic characterization of coxsackievirus A16 (CVA16) strains isolated during an epidemic of hand, foot, and mouth disease (HFMD) in Ningxia Hui Municipality in 2008. METHODS: Clinical samples were collected from HFMD patients in Ningxia Hui Municipality and CVA16 strains were isolated by viral isolation methods. Reverse transcription-polymerase chain reactions (RT-PCR), specific for CVA16 were performed with these CVA16 strains. Entire VP1 coding region amplification and sequencing were then performed and finally phylogenetic tree was constructed among Ningxia CVA16 strains and CVA16 representative strains of known genotypes and subgenotypes. RESULTS: 70 Ningxia CVA16 strains were isolated from HFMD patients in Ningxia in 2008 and the homology of nucleotide and amino acid were 90.8%-100.0% and 98.9% - 100.0%, respectively. Phylogenetic characteristics of the strains reconfirmed that they could be divided into two distinct genotypes-A and B. Genotype B could be further divided into the subgenotypes B1 and B2, while all the 70 Ningxia CVA16 strains belonged to the co-circulated clusters B1a and B1b within subgenotype B1, which belonged to 2 viral transmission chains. CONCLUSION: Our results indicated that subgenotype B1 CVA16 strains continued to circulate over a wide geographic area of mainland China since the first reported episode in Shenzhen city in 1999. Like other CVA16 strains isolated elsewhere in China, both B1a and B1b evolution branches were co-circulating in Ningxia Hui Municipality. Based on the close phylgenetic and chronological relationship with CVA16 isolated in other countries and regions near China. Our data confirmed that these strains co-evolved and co-circulated with those from neighboring countries and regions.

[Seroepidemical study of Coxsackievirus A 16, in four provinces, China, 2005].

OBJECTIVE: To study the situation of 1- 5-years-old children's antibody against Coxsackievirus A group 16 strain (CVA16) in Guangdong, Heilongjiang,Yunnan Province and Xinjiang Uygur Autonomous Regions, China, 2005, it can offer scientific evidences for preventing and controlling CVA16 causative hand-food and mouth disease. METHODS: Using microneutrilization test, to study 503 serum samples randomly selected from sera collected in 2005. RESULTS: Positive rate of anti-CVA16 antibody were 41.90%, 9.40%, 40.00% and 34.40% in Guangdong, Heilongjiang,Yunnan and Xinjiang, respectively. Antibody titer was relative low (average, 1: 6.1) and there was no statistical difference of geometry mean of antibody titer (GMT) among Guangdong, Heilongjiang, Yunnan (F = 0.97, 0.40, 1.06, respectively; P > 0.05), while there had statistical difference of GMT between Heilongjiang and other three regions( F = 10.61, P < 0.00). CONCLUSIONS: There had probably existed local epidemic in some regions of Guangdong, Heilongjiang, Yunnan Province and Xinjiang Uygur Autonomous Regions, China, 2005 or even before, but the area and degree of transmission and epidemic had difference. Children aged from 1- 5-years-old were relatively susceptible population of CVA16 infection.

[The epidemiologic and virological analysis of an outbreak of hand, foot, and mouth disease in Inner Mongolia in 2007].

In 2007, an outbreak of hand, foot, and mouth disease (HFMD) occurred in Jungar Banner, Erdos city, Inner Mongolia Autonomous Region, China Fever, vesicular exanthema on the hands, feet, mouth, and buttocks were presented in most of the patients. Most of the patients were infants less than 5 years old, and an obvious peak period appeared in the disease outbreak. From 28 hospitalized patients, 23 stool specimens and 6 throat swab specimens were collected for enterovirus isolation, and 15 enteroviruses were isolated, 9 were identified as Human Enterovirus 71 (HEV71, the isolation rate is 31.03%) and 1 was identified as Coxsackievirus A16 (CVA16). According to the comprehensive analysis of clinical manifestation, epidemiology data and laboratory results, this outbreak was probably mainly caused by HEV71. The variability at nucleotide acid level and amino acid level among 9 HEV71 was relatively low, and the homology was more than 99.4% and 99.0% respectively, showing that this outbreak was caused by only one viral transmission chain. Phylogenetic analysis of 9 HEV71 strains isolated during this outbreak revealed that they all belonged to subgenotype C4, which has been continuously circulating in mainland China since its first reported occurrence in Shenzhen City in 1998. It was also suggested that subgenotype C4 HEV71 had a widely distribution and transmission in mainland China.

An outbreak of hand, foot, and mouth disease associated with subgenotype C4 of human enterovirus 71 in Shandong, China.

BACKGROUND: An outbreak of hand, foot, and mouth disease (HFMD) included 1149 people in Linyi City, Shandong Province, China, in 2007: three children died. OBJECTIVES: To characterize the pathogens responsible for this outbreak and to analyze their genetic features. STUDY DESIGN: A total of 233 clinical specimens were collected from 105 hospitalized patients, including 11 patients with severe HFMD. Virological investigations (direct RT-PCR, viral isolation and molecular identification) and phylogenetic analysis were performed. RESULTS: Human enterovirus 71 (HEV71) was the main pathogen that caused this outbreak, based on clinical manifestations, epidemiological data, and laboratory results. Phylogenetic analysis indicated that the Shandong HEV71 isolates belonged to 3 lineages in subgenotype C4. Subgenotype C4 could be further divided into two clusters (C4a and C4b), which corresponded to two time periods. Cluster C4a HEV71 has been the predominant virus circulating in mainland China in the past 5 years. CONCLUSIONS: The 2007 HFMD outbreak was mainly caused by HEV71 subgenotype C4 with 3 transmission chains. This virus has been continuously circulating in China since 1998. The Shandong strains co-evolved with isolates from other provinces in mainland China and neighboring countries.