By the mid-20th century, some scientists thought that medicine had conquered infectious diseases.
LOKO vativi va sayense va yi tshubula ro sungula khemikhali ya swidlayaswitsongwatsongwana exikarhi ka va-1900, madokodela a ma ri ni ntshembo wa leswaku mirhi leyi leyintshwa a yi ta herisa mavabyi yo karhi.