Kammala wannan jumla: Nazarin da John Snow yayi game da
cutar kwalara a Landan ana daukar ta a matsayin binciken muhalli na farko da ya magance matsalar kiwon lafiya. Ya yi amfani da taswirar mutuwar da cutar kwalara ta yi don sanin cewa tushen cutar kwalara famfo ne a kan Broad Street. Ya cire makullin famfo a shekara ta 1854 kuma mutane sun daina mutuwa a can. Sai da Robert Koch ya gano ƙwayoyin cuta bayan shekaru da yawa ne aka fahimci yadda cutar kwalara take yaɗuwa.