▁dep ended ▁on ▁trained ▁local ▁el ites ▁and ▁officials ▁to ▁carry ▁out ▁the ▁san itation ▁improvements , ▁quar ant ines , ▁in oc ulations , ▁hosp it als , ▁and ▁local ▁treatment ▁cent ers ▁that ▁were ▁needed . ▁ ▁For ▁example , ▁local ▁mid w ives ▁were ▁trained ▁to ▁provide ▁mat ernal ▁and ▁infant ▁health ▁care . ▁ ▁Pro pag anda ▁campaign s ▁using ▁post ers , ▁r al lies , ▁and ▁later ▁films ▁were ▁used ▁to ▁educ ate ▁the ▁general ▁public . ▁ ▁A ▁serious ▁challenge ▁came ▁from ▁the ▁intens ified ▁use ▁of ▁multiple ▁transport ation ▁routes ▁and ▁the ▁emer gence ▁of ▁central ▁hub s ▁such ▁as ▁Hong ▁Kong ▁all ▁of ▁which ▁facil itated ▁this ▁spread ▁of ▁ep ide m ics ▁such ▁as ▁the ▁pl ague ▁in ▁the ▁ 1 8 9 0 s , ▁thus ▁sharp ly ▁increasing ▁the ▁priority ▁of ▁public ▁health ▁programs . ▁ ▁Michael ▁Wor bo ys ▁arg ues ▁that ▁the ▁ 2 0 th - century ▁development ▁and ▁control ▁of ▁tropical ▁dise ases ▁had ▁three ▁phases : ▁protection ▁of ▁Europe ans ▁in ▁the ▁colon ies , ▁improvement ▁in ▁health ▁care ▁of ▁employ able ▁n atives , ▁ ▁and ▁finally ▁the ▁system atic ▁attack ▁on ▁the ▁main ▁dise ases ▁of ▁the ▁n atives . ▁B EL RA , ▁a ▁large - scale ▁program ▁against ▁le pro s y , ▁had ▁policies ▁of ▁isol ation ▁in ▁newly ▁established ▁le per ▁colon ies , ▁separation ▁of ▁health y ▁children ▁from ▁inf ected ▁parents , ▁and ▁the ▁development ▁in ▁Britain ▁of