Study On Viral Spectrum Of Influenza-like Illness In Shijiazhuang In2011

Objective: To investigate the pathogen spectrum of influenza-like illnessin Shijiazhuang of Hebei Province. To master the different respiratory viruseepidemiological characteristics and to provide scientific basis for the diagnosisand prevention of the respiratory infection.Methods:1The data of ILI (influenza-like illness) in Shijiazhuang of Hebei province in2011were collected from China Influenza Surveillance Information System,which were analyzed by using Excel software in order to master the epidemictrend of ILI.2RNAs were extracted from the throat swabs specimens collected from theILI at four sentinel hospitals. The specimens were detected for15respiratoryviruses by multiplex polymerase chain reaction (multiplex PCR). After1.5%agarose gel electrophoresis, the amplified products were observed andestimated for the type of virus through gel imaging system.3The ILI-positive specimens detected by Multiplex PCR were isolated forinfluenza virus with MDCK cells in vitro.4The purified PCR products of human Boca virus and humanmetapneumovirus virus were sequenced, which were compared withrepresentative strains in recent years by using DNAStar software.5. All the results were statistic analyzed with Excel and SPSS16.0by usingχ~2test andα=0.05.Results:1There were2289816patients of out-patient clinic (OPD) in2011Hebeiprovince, of which,39396(1.72%) cases were ILI. The peak (2.13%) ofpercentage of ILI was in the4th and5th weeks, which was higher indepartment of pediatric than that in department of internal medicine. 2532clinical specimens were collected by four sentinel hospitals fromJanuary to December in2011.228(42.85%) specimens were positive for atleast one of15viral pathogens, including31(5.83%)cases of co-infection.304(57.14%)specimens were negative for viruses.3The distribution of pathogens among532illness was as follows:38(7.14%)cases were infected with adenovirus,36(6.77%) respiratory syncytial virus A,30(5.64%) enteroviruses,26(4.88%) rhinovirus,25(4.70%) influenza virustype A,9(1.69%) parainfluenza3viruses,9(1.69%) coronavirus OC43,6(1.13%) parainfluenza1,5(0.94%) coronavirus229E,3(0.56%) parainfluenza2,6(1.13%) human metapneumovirus,2(0.37%) human Boka viruses,2(0.37%) influenza B. The three top pathogens were adenovirus, respiratorysyncytial virus type A and human enteroviruses.4A total of31cases with co-infection were detected by Multiple PCR,including25cases of double viruses infection and6cases of three virusesinfection. Adenovirus plus respiratory syncytial virus A was the most commonco-infection pattern. Adenovirus or rhinovirus combined with other viruswere the main pattern of co-infection, respectively.5Different age groups had susceptibility to different viruses. Respiratorysyncytial virus A, adenovirus, enteroviruses were the main viruses infected inthe group under5years old. Adenovirus, enteroviruses and rhinovirus werethe main viruses in the group under15years old. Influenza A virus, respiratorysyncytial virus A, adenovirus were the main viruses in the group over15yearsold.6Influenza virus type A appeared frequently from Januray to March,occasionally in August and September. Enteroviruses could be detected fromApril to November, and the peak in summer and autumn. Coronavirusinfection mainly appeared from July to November. The adenovirus appearedalmost all the year round, without clear seasonal difference.7Twenty-seven specimens, which was positive for influenza, were inoculatedinto MDCK cells flasks for the isolation of influenza virus.15(66.67%)influenza virus were obtained, including9Pandemic (H1N1)2009viruses,5 influenza A H3N2viruses, and1influenza B (Yamagata) viruses.8The nucleotide homology of NP1gene between two Boka virus fromShijiazhaung was99.6%, which had99%~100%homology with referencestrain NP1gene published in Genbank.Homology analysis indicated that the homology of M gene among threehuman metapneumovirus from Shijiazhuang was86.1%~99.7%. One strain(HMPV-1) belonged to A2b branch, and another two strains (HMPV-2,HMPV-3) belonged to B1branch. The results showed that humanmetapneumovirus A and B genotypes had been prevalent in Shijiazhaung ofHebei province.Conclusion:1The percentage of ILI at sentinel hospital is1.72%in Shuijiazhuang in2011,peak at the4th and5th weeks.2The positive rate of ILI specimens for15kinds of viral pathogens is42.85%(228/532), including5.83%(31/532) co-infection.3The three top pathogens are adenovirus, respiratory syncytial virus type Aand human Enteroviruses. Adenovirus and rhinovirus combined with othervirus are the main pattern of co-infection.4The influenza A viruses appear frequently from Januray to March.Enteroviruses can be detected frequently from April to November.Coronavirus infection mainly appears from July to November. While theadenovirus appear almost all the year round, without clear seasonal difference.5The Boka virus and human metapneumovirus are prevalent in Shijiah-zuangof Hebei province.6Multiple RT-PCR is superior to the other traditional methods for thedetection of virus among ILI, especially for the patients with co-infection.