Impact of infectious diseases on war

Wartime epidemics of infectious diseases have decimated the fighting strength of armies, caused the suspension and cancellation of military operations, and brought havoc to the civil populations of belligerent and nonbelligerent states. This article summarizes the principal factors that have contributed to the spread of infectious diseases in past wars and reviews the associated demographic losses in military and civil populations. Drawing on the detailed epidemiologic records for the United States Army, case studies of the spread of infectious diseases in relation to military mobilization are presented for the American Civil War, Spanish-American War, and World War I. The article concludes with a brief overview of infectious disease activity in high- and low-intensity conflicts of the late twentieth and early twenty-first centuries.