HFMD Epidemiology And Enterovirus71Variation And Survivability In Shanghai

Hand, foot and mouth disease (HFMD) is an acute infectious disease of young children which is caused by a group of human enteroviruses. The most familiar pathogeny are enterovirus71(EV71) and Coxsackie A16virus (CoxA16). The EV71is the most important cause that results in serious central neurological complications and death cases. EV71has been implicated several small and large outbreaks world-wide since it was originally recognized in1974. In recent years, prevalence of EV71infection in the Asia-Pacific region, especially in Southeast Asia, has greatly increased. The large HFMD outbreaks of Taiwan in1998,2000and the Anhui Fuyang HFMD pandemic were caused by EV71infection. Recently, the epidemic of EV71in China mainland has becoming serious, pre-school children are mostly susceptible to EV71infection and there is no effective vaccine available. In addition, the survivability of EV71is strong that easily causes disease spread in children. EV71infection has become an important issue in public health threatening children health. At present, epidemic surveillance and protection of high-risk population are the major measures to decrease the morbidity and mortality caused by EV71. This study monitored and analyzed distribution of entero viruses, viral variation of EV71, children immunity in Shanghai region and survivability of enteroviruses,inactivating effective of disinfections of EV71, as the following five parts:1、Distribution study of enterovirus subtype in Shanghai region, namely etiology surveillance of HFMD from2010to2011in Shanghai region. Monitoring results revealed that most of the HFMD children were1-5years old, the morbidity of children>6years old and infants<6month was low, the amount of boy cases was higher than girl. The etiology surveillance results revealed that the EV71proportion (64.4%) in enteroviruses was higher than CoxA16(22.1%), the hand foot and mouth diseases were mainly caused by the infection of EV71. The proportion of CoxA16in2011(36.1%) was little higher than2010(19.1%), but the dominant proportion of EV71in enteroviruses positive strains had not been changed. The compare of surveillance between severe cases and non-severe cases showed that EV71propotion in EV71positive cases were significant higher among severe cases (87.0%) than non-severe cases(57.4%). The monitoring results by month in2010showed that there was some seasonal principle:There was no significant peak during this year, the enteroviruses positive rate kept high level during May and December, The monitoring results by month in2011revealed that the high positive rate began in March. In conclusion, the key point of HFMD prevention and control in Shanghai region must focus on spring until autumn every year.2> Genetic analysis of enterovirus71in Shanghai region,2010. We chose43EV71strains isolated in2010, Complete VPl gene sequences (891nucleotides) were sequenced. Among these VP1sequences,18EV71VP1sequences which9from fatal cases and9from non-fatal cases were selected, then compared with that of A, B, C genotype reference EV71strains from GeneBank by homogeneity and phylogenetic tree analysis. The results of nucleotide and amino acid homogeneity analysis showed that The nucleotide homogeneity of these18Shanghai strains with the representative isolates of A and B genotypes were81.5%-82.6%and83.4%-84.2%respectively, the amino acid homogeneity were94.3%-95.0%and96.6%-97.0%respectively; The nucleotide and amino acid homogeneity with the representative isolates of C were87.4%-99.2%and98.7%-100.0%. Especially, the homogeneity with the Fuyang EV71strains (representative of C4subtype) appeared to be97.8%-99.2%and99.3%-100.0%respectively. These43EV71isolated strains were within genotype C subgenogroup C4in the phylogenetic tree. There was no remarkable diversity between the EV71isolates from the9fatal and9non-fatal cases in VPl gene.3、The antibody levels against enterovirus71(EV71) detected in Shanghai healthy children, to understand the children susceptibility and the immunity due to past infection. And to investigate the epidemic trends of EV71-associated-hand, foot and mouth diseases (HFMD) in children. We detected the EV71antibody by neutralization test. Results showed that the positive rate of EV71antibody among the overall93children sero specimens was58.1%, the geometric mean titer (GMT) of EV71-specific neutralizing antibody was1:14.48, No significant gender-specific difference in antibody positive rate or GMT was observed. The antibody positive rate and GMT were associated with age of the children. The antibody positive rate of infants under6months old was87.5%, and the GMT was1:9.56; From2to3years old, the antibody positive rate of children decreased to3.7%, GMT decreased to1:4.21, with statistics significances; The antibody positive rate obviously increased to88.3%among children aged5-6years old, with the GMT of1:21.74; There was no statistic differences between children aged7-8years old and5-6years old in antibody positive rate or GMT. It is obviously that children older than5years old have immunity to EV71infection due to past infection,children aged2-3years old are susceptible to EV71infection, It is important to take prevention measures to protect them from EV71-associated-HFMD.4^The study of survivability of enteroviruse isolates in tap water for daily use, to forecast the potential risk of water-borne virus’transmission. We chose5enterovirus71strains and1Coxsackie virus strain from enterovirus isolates in Shanghai and Zhejiang districts from2009to2010. The6viruses were mixed with CI-1.Omg/L tap-water and then inoculated into Vero cells, then observe the CPE everyday in order to survey the survivability of each virus, analyze the decline of virus’survivability by scatter diagram. Results showed that the6enterovirus strains could survive longer than one month in tap water which initial CL concentration is1.0mg/L and still have celluar infectivity. The survivability was varied in the enterovirus isolated from different HFMD cases. We can see that the survivability of enterovirus71and Coxsackie virus is quite strong in water. During the period of HFMD epidemic, it is suggested that cites, countries and the combined parts of urban and rural should pay great attention on the risk of water-borne enterovirus’transmission.5> Study of the EV71inactivating efficacy of common disinfectants for hands, in order to choose reasonable and effective disinfectants for prevention of HFMD transmission. We used suspension test to observe the efficacy of each disinfectants. The results showed that the inactivating rate of EV71exposed to A disinfectant gel and B hand antisepsis for lmin and5min attained higher than99.9%; The inactivating rate of EV71exposed to C synergy for lmin and5min attained higher than99.99%; While inactivating rate of EV71exposed to the laboratory-made antisepsis for lmin and5min attained to100%The laboratory-made antisepsis (77%alcohol+2%glycerin) which is recommended by WHO have higher inactivating efficacy and lower virulence, It can be used as an daily-use disinfectant for viral infectious diseases prevention. At present, we are evaluating the effect of HFMD prevention on this kind of antisepsis in several kindergartens and child-care centers in Shanghai.