During World War I, disease proved a potent ally of the Ottoman bid to commit genocide against the Armenians. More than two decades later, Armenian refugees resettled by the French Mandate were still vulnerable to epidemic disease. As many as half of those resettled from the Hatay province to ‘Anjar and Tyre perished due to epidemics. During the Mandate period malaria, in particular, remained a fact of life in rural Lebanon until a paradigm shift in global public health that followed World War II. Palestinian refugees, unlike the Armenians, were largely spared epidemic disease and have inhabited camps –in some cases the exact same refugee camps that disease forced Armenian populations to abandon—since 1948. Their status as permanent refugees hinged on the use of DDT and other health technologies that proliferated in the post-war period. That watershed transformed the nature of war in the Middle East, I hypothesize, by prolonging conflicts and their attendant refugee crises. This comparative analysis of disease in Armenian and Palestinian refugee camps seeks to assess the disease environments for refugees throughout the twentieth century in Lebanon. Contrary to the prevailing scholarly understanding that World War I and its aftermath saw disease ecologies transformed, this paper argues that disease environments post-war were largely similar to those of the late Ottoman period.