Studies On Hand, Foot And Mouth Disease Epidemiology And Etiology In Jing’an District,Shanghai

In order to understand the epidemiological characters of Hand, foot and mouth(HFMD) Disease from2005to2010in Jingan District, Shanghai, we collected information from conventional reports and monitoring data. To analyze the distribution of enterovirus genera which caused HFMD and know the characteristic of VP1gene of EV71isolates, we collected specimens from clinical diagnoized cases from2009to2010in our district using RT-PCR and cell culture technologies. Thus, we could have an idea of the prevalent and the molecular epidemiological characteristics of HFMD. We made an experiment to know the efficacy of inactivating Enterovirus71by disinfectant with Chlorine, which provided a good evidence for making measures for control and prevention of HFMD. This study include several parts as below:1.Epidemiological characters of Hand, foot and mouth Disease from2005to2010in Jingan Dstrict, ShanghaiThe incidence of HFMD was (/10million)20.44、18.72respectively from2005to2006in Jingan District. The incidence was lower in2006than2005. The incidence of HFMD was (/10million)31.32.24.84respectively from2007to2008. The incidence was lower in2008than2007. The incidence of HFMD gradually grew higher after2008, but2007was the highest. The highest peak of HFMD was about from May to July each year. There was another highest peak in Nov,2009because of the outbreak of HFMD from a certain kindergarten in our district.The incidence of HFMD was higher in Caojiadu and Jiangning community which located in the northwest region of our district than other communities. Male to female ratio was1.4:1.Children under5years old reached to83.8%among all the cases.Children in the kindergartens owned the highest proportions.2. Analyze the monitoring data of etiology of HFMD from2009to2010in Jingan District, Shanghai90、180、242throat swabs and anus swabs of clinical diagnoized cases from Children’s Hospital of Shanghai were collected respectively from2009to2011using Real-time RT-PCR. It revealed that the positive rate of Coxsackie virus A16(CA16) gradually dropped from2009to2011, while the positive rate of Enterovirus71(EV71) and other viruses of Enterovirus(EV) showed a gradual upward trend.We collected175specimens matched with throat swabs and anus swabs from clinical diagnoized cases from Jul,2010to Dec,2011to detect EV71、CA16、EV by Real-time RT-PCR. We compared the difference of detection rates between throat swabs and anus swabs by McNemar test. It showed that the difference was statistically significant for EV71and EV by detecting matched specimens, P<0.05, while the difference was not statistically significant for CA16. Test results are basically the same by using Kappa test, Kappa>0.4.Compared the different results of EV71,CA16and EV between paired specimens with collecting time, we made an inference that the enterovirus might get proliferation in2days after onset in the pharyngeal. The enterovirus may probably by transmitted by respiratory system at this time.Analyzed the experiment results of175paired specimens by Real-time RT-PCR with sampling time, it revealed that the it was positive for EV71of throat swabs3days after onset, while it was negative for CA16and EV of throat swabs. It can be inferred that it might need more time for EV71to eliminate by throat than CA16and EV.3.Studies on the genetic evolution of Enterovirus71of Jingan District, ShanghaiWe randomly selected19specimens with PCR positive in different months in2010to be cultured by Vero cells. One specimen was collected from severe case, the other from ordinary cases. According from phylogenetic tree for EV71VP1region(1200bp),19isolates of EV71in Jingan District were similar with the isolates from Fuyang, Anhui Province in2008, which were belonged to the genotype C4a.We compared the VP1nucleotide homogeneity and amino acid homogeneity between19isolates of Jingan District and representative genotype A, B, C1, C2, C3, C4, C5downloading from Genebank, of which genotype C4was the epidemic strain of Fuyang, Anhui in2008. It demonstrated that the nucleotide homogeneity compared19isolates to genotype C was84.3%～97.1%, and the amino acid homogeneity was88.6%～98.3%, while to genotype C4was95.0%～97.1%, and the amino acid homogeneity was95.1%～98.3%.Since the first genotype of C4b was identified in Guangdong Province in1998, it continued to circulate in mainland China until2003.From2003to2004, genotype C4a and C4b coexisted in Zhejiang,Guangdong Province and Taiwan. From2005till now, genotype C4a were isolated from Shanghai, Henan, Yunnan, Beijing, Shandong, Anhui and Zhejing Province. There was no difference in genotype between severe cases and ordinary cases. However, other countries such as United States, Australia, Malaysia, Singapore and Japan appeared to have different genotypes of EV71in different years..4.Study on the efficacy of inactivating Enterovirus71by disinfectant with ChlorineAs we all know that Enterovirus71can be transmitted by fecal oral route and close contact. Nowadays, kindergartens in Shanghai often use500mg/L disinfectant with Chlorine to disinfect toys, towels, desks and doorknobs. We made an experiment to know the efficacy of inactivation of EV71using500mg/L disinfectant with Chlorine. Because of the toxic to the cells, it showed that it took only five minutes of500mg/L to reach the99.99%killing rate, which has the same result of1000mg/L. As we used EV71suspension to make the experiment, the disinfectant could act with virus directly. In daily work, such as soaking towels or clothes, etc, the efficacy of disinfectant with Chlorine would be affected by stuff containing organics or electrostatic adhesion. So, for the stuff suspected being polluted by HFMD patients, higher concentration of disinfectant with Chlorine(1000mg/L or above) or prolonged sterilizing time were needed to apply in order to guarantee the efficacy of inactivation of virus and control the spread of HFMD.