Search

To explore the genomic characterization of 4vaccine-derived poliovirus(VDPV)strains isolated from 2acute flaccid paralysis(AFP)cases in Yunnan Province in 2010 and 2012,respectively,the complete genome sequences of the 4strains were determined. Sequence analysis revealed that the complete genome length of the type Ⅱ and type Ⅰ VDPV was 7439nt and 7441 nt, respectively. Nucleotide and amino acid sequence similarities of type II VDPV were 95.4% and 97.7%,respectively,and type I VDPV were93.9% and 97.9%,respectively as compared with those of Sabin strains. Nucleotide substitutions were found at two important attenuation sites (nt 481 and nt in type Ⅱ VDPV, and three important attenuation sites(nt480,nt2795 and nt6203)in type I VDPV. Type 2 and type 1VDPV strains had 1.0% and2.3% divergence with Sabin strains, respectively. Similarity plot analysis showed multiple recombination events in the genome of the 4strains,which showed that the recombination was common and complex. Analysis of the characteristics of VDPVs on molecular level could provide valuable information on evolutionary dynamics and lay foundation for developing scientific and feasible strategy to control VDPV.

Vaccination in prevention mother-to-child transmission (PMTCT) of hepatitis B has been recommended since plasma-derived hepatitis B vaccines became available in China in 1986; however, less study evaluated practice effectiveness of PMTCT systematically. We conducted a prospective survey to evaluate the effectiveness of PMTCT practices in 3 provinces of southern China. We selected prefectures with low timely birth dose coverage in Yunnan, Guangxi, and Hunan provinces. Infants born to HBsAg positive mothers were evaluated at 7–12 months of age. We tested hepatitis B virus (HBV) surface antigen (HBsAg) and HBV e antigen (HBeAg) of mothers and tested HBsAg of infants born to HBsAg positive mothers using Enzyme-linked Immunosorbent Assay (ELISA) at provincial CDC laboratories. We used logistic regression analysis to analyze the risk factors for HBV infection. Among 3,094 infants born to HBsAg positive mothers, 172 were positive for HBsAg (5.6%). HBeAg status of pregnant women, timely birth dose (TBD) of hepatitis B vaccine were major predictors for HBV infection of infants. PMTCT practices greatly reduced the prevalence of HBsAg among infants born to HBsAg positive mothers China. However, the effectiveness of strategies used in PMTCT varied. HBsAg screening for pregnant women, monitoring of infants born to HBsAg positive mother should be enhanced to evaluate the effectiveness of program.

Enterovirus B83 (EV-B83) is a recently identified member of enterovirus species B. It is a rarely reported serotype and up to date, only the complete genome sequence of the prototype strain from the United States is available. In this study, we describe the complete genomic characterization of an EV-B83 strain 246/YN/CHN/08HC isolated from a healthy child living in border region of Yunnan Province, China in 2008. Compared with the prototype strain, it had 79.6% similarity in the complete genome and 78.9% similarity in the VP1 coding region, reflecting the great genetic divergence among them. VP1-coding region alignment revealed it had 77.2–91.3% with other EV-B83 sequences available in GenBank. Similarity plot analysis revealed it had higher identity with several other EV-B serotypes than the EV-B83 prototype strain in the P2 and P3 coding region, suggesting multiple recombination events might have occurred. The great genetic divergence with previously isolated strains and the extremely rare isolation suggest this serotype has circulated at a low epidemic strength for many years. This is the first report of complete genome of EV-B83 in China.

In China, 5 patients with acute flaccid paralysis (AFP) associated with type 2 vaccine-derived poliovirus (VDPV) were identified by an AFP surveillance system from 1996 through 2009. A maximum-likelihood tree shows that all 5 Chinese VDPVs were independent. These 5 VDPVs were 100-216 d old according to the number of synonymous substitutions per synonymous site and 176-292 d old according to the number of substitutions per site. This result indicates limited virus replication since the administration of the initiating oral polio vaccine (OPV) dose, which is consistent with the rapid evolution rate of poliovirus genomes. The above-mentioned VDPVs have important implications in the global polio eradication initiative. Localized, limited, and transient circulation may be typical of OPVs; hence, independent VDPVs could be found because of the large population and excellent surveillance system, which permitted early detection and response, but sustained transmission was limited because of high population immunity.

Better understanding of transmission patterns will enhance control and elimination programs., To determine the origin of the virus associated with a measles outbreak in Menglian County, Yunnan Province, People’s Republic of China, in 2009, we conducted genetic analyses. Phylogenetic analyses based on nucleoprotein (N) and hemagglutinin (H) gene sequences showed that these Menglian viruses were not closely related to sequences of any World Health Organization (WHO) reference strains representing the 23 currently recognized genotypes. The minimum nucleotide divergence between the Menglian viruses and the most closely related reference strain, genotype D7, was 3.3% for the N gene and 3.0% for the H gene. A search of the databases of GenBank, WHO, and the Health Protection Agency Measles Nucleotide Surveillance showed that the Menglian viruses, together with the 2 older non-Menglian viruses, could be members of a new proposed measles genotype, d11. The new genotype designation will allow for better description of measles transmission patterns, especially in the Southeast Asian and Western Pacific regions.

Background Industrialization and demographic transition generate nonstationary dynamics in human populations that can affect the transmission and persistence of infectious diseases. Decades of increasing vaccination and development have led to dramatic declines in the global burden of measles, but the virus remains persistent in much of the world. Here we show that a combination of demographic transition, as a result of declining birth rates, and reduced measles prevalence, due to improved vaccination, has shifted the age distribution of susceptibility to measles throughout China. Methods and findings We fit a novel time-varying catalytic model to three decades of age-specific measles case reporting in six provinces in China to quantify the change in the age-specific force of infection for measles virus over time. We further quantified the impact of supplemental vaccination campaigns on the reduction of susceptible individuals. The force of infection of measles has declined dramatically (90%–97% reduction in transmission rate) in three industrialized eastern provinces during the last decade, driving a concomitant increase in both the relative proportion and absolute number of adult cases, while three central and western provinces exhibited dynamics consistent with endemic persistence (24%–73% reduction in transmission rate). The reduction in susceptible individuals due to supplemental vaccination campaigns is frequently below the nominal campaign coverage, likely because campaigns necessarily vaccinate those who may already be immune. The impact of these campaigns has significantly improved over time: campaigns prior to 2005 were estimated to have achieved less than 50% reductions in the proportion susceptible in the target age classes, but campaigns from 2005 onwards reduced the susceptible proportion by 32%–87%. A limitation of this study is that it relies on case surveillance, and thus inference may be biased by age-specific variation in measles reporting. Conclusions The age distribution of measles cases changes in response to both demographic and vaccination processes. Combining both processes in a novel catalytic model, we illustrate that age-specific incidence patterns reveal regional differences in the progress to measles elimination and the impact of vaccination controls in China. The shift in the age distribution of measles susceptibility in response to demographic and vaccination processes emphasizes the importance of progressive control strategies and measures to evaluate program success that anticipate and react to this transition in observed incidence., Matthew Ferrari and colleagues use a mathematical modelling approach to explore the contribution of both demographic forces and immunization programs to the changing age-distribution of measles cases in China., Author summary Why was this study done? Though the incidence of measles has been greatly reduced, achieving elimination remains a significant public health challenge. The epidemiology of measles, in particular the age-specific patterns of incidence, is strongly influenced by both demographic rates and vaccination and control efforts. China has observed an increase in the number and proportion of measles cases in adults in recent years, a pattern that has been seen in many other countries with successful vaccination programs. Our study was designed to quantify the contribution of both demographic forces and immunization programs to the changing age distribution of measles cases in China. What did the researchers do and find? We analyzed 30 years of age-specific measles case reports from six provinces in China using a novel model that accounts for the impact of demographic change and age-targeted vaccination campaigns. We found that the increase in adult cases in China is more pronounced in eastern provinces and is consistent with indirect protection from exposure to measles infection in childhood due to herd immunity, but age incidence patterns in the central and western provinces are consistent with continued endemic measles transmission. We estimate that while historical supplemental vaccination campaigns resulted in lower immunity than expected based on coverage, recent campaigns have resulted in substantial improvements in population immunity. What do these findings mean? Progress towards measles elimination at the national level is often heterogeneous in space. Demographic and age-specific case surveillance data, linked via epidemiological models, can be integrated to provide evaluation of vaccine program performance.

To explore the efficacy of prevention programs and relevant factors targeting mother-to-infant transmission of HBV in Yunnan province.In Yunnan province, we selected HBsAg positive pregnant women that delivered in hospital from January 1st through June 30th, 2011. Newborns of these pregnant women were under PMTCT (prevention of mother to child treatment) program and followed. Every infant was drawn 2 ml venous blood and questionnaire survey was carried out when the baby was 7-12 month-old and completed the vaccination processes. Serum samples of them were then collected and detected on the 5 serological indicators of HBV.were analyzed statistically.There were 2 765 infants in the study program. The success rate of PMTCT was 95.88% . Rates of coverage on both timely-birth dose and 3 doses of HepB were 97.03% and 92.30% respectively. The overall vaccinated rate and timely-birth vaccinated rate on hepatitis B immunoglobulin (HBIG) were 68.97% and 94.49% respectively. The success rate of PMTCT was 97.16% after administration of passive-active immune-prophylaxis (HepB and HBIG), compared to the rate as 93.01% when vaccinated with HepB only. Significant differences were seen in the successful rates of PMTCT between combined and non-combined immunization. Either the combined or non-combined immunization, there were significant differences seen in the success rates of PMTCT regardless the positivity status of HBsAg or HBeAg, among the infected mothers.The efficacy of passive-active immune-prophylaxis program seemed to be better than the one without combined immunization. It was vitally important for the infants whose mothers' HBsAg and HBeAg status were positive, to receive regular and timely combined immunization. In order to promote the PMTCT in Yunnan province, vaccinated rate on HBIG should be further improved.

Human enterovirus B106 (EV-B106) is a recently identified member of enterovirus species B. In this study, we report the complete genomic characterization of an EV-B106 strain (148/YN/CHN/12) isolated from an acute flaccid paralysis patient in Yunnan Province, China. The new strain had 79.2-81.3% nucleotide and 89.1-94.8% amino acid similarity in the VP1 region with the other two EV-B106 strains from Bolivia and Pakistan. When compared with other EV serotypes, it had the highest (73.3%) VP1 nucleotide similarity with the EV-B77 prototype strain CF496-99. However, when aligned with all EV-B106 and EV-B77 sequences available from the GenBank database, two major frame shifts were observed in the VP1 coding region, which resulted in substantial (20.5%) VP1 amino acid divergence between the two serotypes. Phylogenetic analysis and similarity plot analysis revealed multiple recombination events in the genome of this strain. This is the first report of the complete genome of EV-B106.

Objective To explore the risk factors associated with immunoprophylaxis failure against mother to child transmission of hepatitis B virus (HBV) and hepatitis B vaccination status in Yunnan province, China. Methods Multicenter cluster sampling was used to select pregnant women who were positive for hepatitis B surface antigen (HBsAg). HBV immunoprophylaxis was carried out for the newborns. Blood samples were collected and tested for HBV markers from 7 to 10 month old infants. The factors were analyzed by univariate and logistic regression. Results A total of 2765 mothers and their infants were enrolled. The failure rate of prevention of mother to child transmission (PMTCT) was 4.12%. The rate of timely HepB1 vaccination within 24 h was 98.04%, the rate of three-dose vaccination was 92.30% and the rate of hepatitis B immune globulin (HBIG) administration was 68.97%. Place of residence, maternal education, gestational age and birth weight were related to administration of HBV immunoprophylaxis. It was remarkable that the rate of HBIG administration of infants was only 63.89% with whose mothers were both HBsAg and hepatitis B e antigen (HBeAg)-positive. Further analysis showed that there were three risk factors associated with HBV immunoprophylaxis failure: mothers who were positive for HBsAg and HBeAg, maternal HBVDNA level, and HBIG administration or not. Conclusions PMTCT of HBV was well implemented in Yunnan. However, in order to achieve optimal prevention of vertical HBV transmission, it is mandatory to make additional efforts to improve the implementation of regulatory HBV immunoprophylaxis, especially for HBsAg-positive pregnant women.

We acknowledge the letter of [Arya and Agarwal][1] ([1][2]). Children

The epidemiologic and genetic characteristics of mumps viruses detected in China from 1995 to 2010 were analyzed in this study. Mumps remains endemic in China with a high overall incidence rate. The incidence of mumps in Western China was higher than that in other regions of the country. Each year, most of mumps cases occurred between April and July, but a small peak also occurred in November and December. Mumps cases primarily affected the under 15 year old age group. Virologic data demonstrated that genotype F was the predominant circulating genotype throughout China for at least 15 years and no other genotype was detected between 1995 and 2010. Analysis of sequence data from the small hydrophobic (SH) gene indicated that multiple transmission chains of genotype F were found in various provinces of China, with no apparent chronologic and geographic restriction. This is the first report describing the epidemiology of mumps and genetic characterization of mumps viruses at the national level in China.

Despite remarkable progression toward polio eradication worldwide, wild poliovirus (WPV) importation has been a great challenge for China, as it shares borders with countries where WPV is endemic. The objective of this study was to estimate poliovirus antibody seroprevalence among children

The incidence of measles in China from 1991 to 2008 was reviewed, and the nucleotide sequences from 1507 measles viruses (MeV) isolated during 1993 to 2008 were phylogenetically analyzed. The results showed that measles epidemics peaked approximately every 3 to 5 years with the range of measles cases detected between 56,850 and 140,048 per year. The Chinese MeV strains represented three genotypes; 1501 H1, 1 H2 and 5 A. Genotype H1 was the predominant genotype throughout China continuously circulating for at least 16 years. Genotype H1 sequences could be divided into two distinct clusters, H1a and H1b. A 4.2% average nucleotide divergence was found between the H1a and H1b clusters, and the nucleotide sequence and predicted amino acid homologies of H1a viruses were 92.3%-100% and 84.7%-100%, H1b were 97.1%-100% and 95.3%-100%, respectively. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Cluster H1a and H1b viruses were co-circulating during 1993 to 2005, while no H1b viruses were detected after 2005 and the transmission of that cluster has presumably been interrupted. Analysis of the nucleotide and predicted amino acid changes in the N proteins of H1a and H1b viruses showed no evidence of selective pressure. This study investigated the genotype and cluster distribution of MeV in China over a 16-year period to establish a genetic baseline before MeV elimination in Western Pacific Region (WPR). Continuous and extensive MeV surveillance and the ability to quickly identify imported cases of measles will become more critical as measles elimination goals are achieved in China in the near future. This is the first report that a single endemic genotype of measles virus has been found to be continuously circulating in one country for at least 16 years.

Fluid jet-dispensing technology has been widely used in micro-electronic encapsulation industry. The fluid viscosity varies as temperature changes, while it affects the process remarkably. Besides basic method on temperature field solution, some thermal behaviors, including heat conduction and heat exchange, boundary conditions and some physical parameters are overall analyzed in this paper. Based on the simulation software platform ANSYS, a two-dimensional transient temperature field model of jet-dispenser was built, and simulation programs on temperature field for two sorts of fluid with obviously different thermal conductivity were performed. Then heating experiments were finished to validate the feasibility of FEA, and results show that temperature distribution is homogeneous along fluid area and it meets the conditions of jetting.

Background This report describes emergency response following an imported vaccine derived poliovirus (VDPV) case from Myanmar to Yunnan Province, China and the cross-border collaboration between China and Myanmar. Immediately after confirmation of the VDPV case, China disseminated related information to Myanmar with the assistance of the World Health Organization. Methods A series of epidemiological investigations were conducted, both in China and Myanmar, including retrospective searches of acute flaccid paralysis (AFP) cases, oral poliovirus vaccine (OPV) coverage assessment, and investigation of contacts and healthy children. Results All children