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1、ASwineFluVirusTakesOffinChildrenatMidwesternFairsButMakesLittleHeadwayHands-offlearning.CDCrecommendsthatchildrenwashtheirhandsafterbeingnearpigs.Credit:Muffet/LizWestAnunusualinfluenzavirushascaughttheattentionofpublichealthofficialsbecauseithasrapidlyspreadfrompigsatU.S.countyf
2、airstochildren.Thevirus,avariantofanH3N2strainthatseasonallyinfectshumans,hasnotcausedseveredisease.Scantevidenceexiststhatitcanspreadbetweenpeople,andthevastmajorityofcasesareintwostates.EpidemiologistJosephBreseeoftheU.S.CentersforDiseaseControlandPrevention(CDC)inAtlantaexplai
3、nedinateleconferencetodaythat145caseshavebeenconfirmedsince12July,abigjumpfromlastweekwhenCDCtalliedonly16confirmedcasessincethatdate.“Thisisclearlyasignificantincreasesincelastweek’stotal,”hesaid,addingthatthisreflectsincreasedtestingandthelargenumberofcountyfairsnowtakingplace.
4、Breseesaidthatmorethan90%ofthecasesoccurredinchildren,mostofwhomhaddirectorindirectcontactwithpigs,andallbuttwowereinIndianaandOhio.“Atthispoint,there’snoevidenceofsustained,efficient,human-to-humanspreadinthecommunity,”hesaid.“Ourseasonalinfluenzasystemsareactiveandhavenotshowna
5、nysignsinanincreaseininfluenzaactivity.Thisisnotapandemicsituation.ButofcourseCDCiscontinuingtomonitorthesituationclosely.”H3N2vfirstsurfacedinJuly2011andinfected12additionalpeoplebeforedisappearingthispastwinter.Researcherswereintriguedbecausethevirushasaninternal“M”genethatmatc
6、hesonefoundinthepandemicH1N1virusthatrapidlyinfectedhumansthroughouttheworldin2009and2010.CDCvirologistMichaelShawsayshesuspectstheMgene,whichaffectshowwellthevirusgrowsinitshost,playsaroleinthecurrenttransmissions.“There’ssomethingaboutthatgenethatgivesitanadvantageforcirculatin
7、ginpigs,”Shawsays.“Andifitbecomesmorecommoninpigs,itgivesmoreofachancetojumpintohumans.”ButShawsaysthere’snoevidencethatthisMgenebyitselfleadstohuman-to-humantransmission.ExcludingthisoutbreakandthepandemicH1N1virus,CDChasrecordedonly35totalcasesofinfluenzavirusesstemmingfrompig-
8、to-humantransmissionintheUnitedStatesdur
