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1、JohnSnowandtheBroadStreetCholeraOutbreakof1854CholerareachedtheBritishIslesintheearly1830s,andoutbreakswouldcontinueforthenextfiftyyears.Today,itiswellknownthatcholeraiscausedbythebacteriaVibriacholeraeandisusuallyspreadinpoordrinkingwater.Earlytheoriesblamedtheinfec
2、tiononmistsand'miasmas',whichledtomanyoftheearlyattemptstocontrolcholerafailing.Inrealitythepoorsanitaryconditionsofacity'swatersupplywasresponsible.EarlyVictoriancitiesalsoincludedcowshedsmixedinamongstthehouses.Thesecombinedwithpoorhandlingofhumansewage(oftenmerely
3、aholeintheground)ledtoarapidcontaminationofthedrinkingwater.Indeed,thefamousBroadStreetwaterpump(seebelow)wasashallowwaterpumpthatpumpedwaterfromthecontaminatedwatertable.Inthe1850s,JohnSnowperformedpioneeringdataanalysistoprovehishypothesisthatcholerawasspreadinthed
4、rinkingwater.Thisanalysisifperformedtoday,wouldcomeundertherealmsofGIS(GeographicInformationSystems)andDataMining.SomehaveclaimedhisBroadStreetmapasbeingthefirstexampleofGIS,eventhoughitwasperformedwithapenandpaper.Althoughthisisanexaggeration,theBroadStreetmapitisan
5、excellentexampleofthepowerofmapstoclearlydemonstraterelationshipsincomplexscenarios.Snow'sworkwiththeLondoncholeraoutbreaksofthe1850s,isoftencitedasthebeginningofmodernepidemiology.Unfortunatelywordofthispioneeringepidemiologywasslowtospread,andtheLondoncholeraoutbre
6、akswouldcontinueintothe1880swhenalloftheshallowwater-pumpswerefinallydecommissioned.ThispagelooksatSnow'stwomostfamousanalysiscasesthathelpedtoprovehishypothesisthatcholerainfectionsoccurredthroughdrinkingwater.TheBroadStreetOutbreak,1854Thisisthemostfamouspieceofdat
7、aanalysisperformedbyJohnSnow,andhispromptactionundoubtedlysavedmanylives.TheoutbreakoccurredintheSohoDistrictofLondon,inandaroundBroadStreet.JohnSnowreasonedthatifcholerawasspreadbyamistormiasma,astheprevailingtheoriessuggested,thenthecasesshouldbeuniformlydistribute
8、dalongthestreets.Toseeifthiswasthecase,heplottedeachcholeracaseonamap,similartotheoneontheleft.Healsoplottedhouseswithmultiplecases