AmEriCAnsDECrEAsEInCrEAsingly, historiAns ArE BlAming DisEAsEs importED From thE OlD WorlD For thE stAggEring DispArity(不同) BEtwEEn thE inDigEnous (本土的) populAtion oFAmEriCA in 1492—nEw EstimAtEs oF whiCh soAr As high As 100 million, or ApproximAtEly onE-sixth oF thE humAn rACE At thAt timE—AnD thE FEw million Full-BlooDED NAtivEAmEriCAns AlivE At thE EnD oF thE ninEtEEnth CEntury. ThErE is no DouBt thAt ChroniC DisEAsE wAs An importAnt FACtor in thE prECipitous(险峻的) DEClinE, AnD it is highly proBABlE thAt thE grEAtEst killEr wAs EpiDEmiC DisEAsE, EspECiAlly As mAniFEstED in virgin-soil (处女地) EpiDEmiCs.Virgin-soil EpiDEmiCs ArE thosE in whiCh thE populAtions At risk hAvE hAD no prEvious ContACt with thE DisEAsEs thAt strikE thEm AnD ArE thErEForE immunologiCAlly(免疫学的) Almost DEFEnsElEss. ThAt virgin-soil EpiDEmiCs wErE importAnt inAmEriCAn history is strongly inDiCAtED By EviDEnCE thAt A numBEr oF DAngErous mAlADiEs(病)—smAll pox, mEAslEs(麻疹) ,mAlAriA(疟病), yEllow FEvEr, AnD unDouBtEDly sEvErAl morE— wErE unknown in thE prE-ColumBiAn NEw WorlD、ThE EFFECts oF thEir suDDEn introDuCtion ArE DEmonstrAtED in thE EArly ChroniClEs oFAmEriCA, whiCh ContAin rEports oF horrEnDous (可怕的) EpiDEmiCs AnD stEEp populAtion DEClinEs, ConFirmED in mAny CAsEs By rECEnt EquAntitAtivE AnAlysEs oF SpAnish triButE rECorDs AnD othEr sourCEs. ThE EviDEnCE proviDED By thE DoCumEnts oFBritish AnD FrEnCh ColoniEs is not As DEFinitivE BECAusE thE ConquErors oF thosE ArEAs DiD not EstABlish pErmAnEnt sEttlEmEnts AnD BEgin to kEEp Continuous rECorDs until thE sEvEntiEth CEntury, By whiCh timE thE worst EpiDEmiCs hAD proBABly AlrEADy tAkEn plACE. FurthErmorE , thEBritish tEnDED to DrivE thE nAtivE populAtions AwAy, rAthEr thAn EnslAving thEm As thE SpAniArDs DiD, so thAt thE EpiDEmiCs oFBritishAmEriCA oCCurrED BEyonD thE rAngE oF Colonists DirECt oBsErvAtion. EvEn so, thE surviving rECorDs oF NorthAmEriCA Do ContAin rEFErEnCEs to DEADly EpiDEmiCs Among thE inDigEnous populAtion. In 1616—1619 An EpiDEmiC, possiBly oF BuBoniC or pnEumoniC (肺的) plAguE (瘟疫), swEpt CoAstAl NEwEnglAnD, killing As mAny As ninE out oF tEn.During thE 1630’’s smAll-pox, thE DisEAsE most FAtAl to thE NAtivEAmEriCAn pEoplE, EliminAtED hAlF thE populAtion oF thE Huron AnD Iroquois ConFEDErAtions. In thE 1820’’s FEvEr DEvAstAtED thE pEoplE oF thECoulumBiA RivEr ArEA, killing Eight out oF tEn oF thEm.UnFortunAtEly, thE DoCumEntAtion oF thEsE AnD othEr EpiDEmiCs is slight AnD FrEquEntly unrEliABlE, AnD it is nECEssAry to supplEmEnt whAt littlE wE Do know with EviDEnCE From rECEnt EpiDEmiCs Among NAtivEAmEriCAns. For ExAmplE, in 1952 An outBrEAk oF mEAslEs Among thE NAtivEAmEriCAn inhABitAnts oF UngAvABAy. QuEBEC, AFFECtED 99 pErCEnt oF thE populAtion AnD killED 7 pErCEnt, EvEn though somE hAD thE BEnEFit oF moDErn mEDiCinE.CAsEs suCh As this DEmonstrAtE thAt EvEn DisEAsEs thAt ArE not normAlly FAtAl CAn hAvE DEvAstAting ConsEquEnCEs whEn thEy strikE An immunologiCAlly DEFEnsElEss Community. ThE Author impliEs whiCh oF thE Following stAtEmEnts ABout mEAslEs
A、It is not usuAlly A FAtAl DisEAsE.
B、It CEAsED to BE A proBlEm By thE sEvEntiEth CEntury.
C．It is thE DisEAsE most Commonly involvED in virgin-soil EpiDEmiCs.
D．It wAs not A signiFiCAnt proBlEm in SpAnish ColoniEs.