During WWI, many infections, including vector-borne diseases, were identified as causing mortality, morbidity, and residual impairments. Trench warfare
—a system that was used on the Western Front during WWI to protect soldiers from the effects of modern firepower, which was being used for the first time—is often described in apocalyptic terms. With all of the mud, the rotting corpses, and the rats, it’s not surprising that this form of warfare was particularly conducive to infectious diseases.
WWI-related infections such as trench foot, trench fever (caused by louse-borne Rickettsia quintana
, subsequently called Bartonella quintana
), a range of helminths, intestinal parasites (including Ascaris, Trichuris
and Taenia spp
.), typhus, cholera, tuberculosis, typhoid fever, dysentery, scarlet fever, diphtheria, measles, whooping cough, and smallpox were not uncommon.5
Rape, prostitution, and sexual indiscretion that often occur during wars encourage the proliferation of venereal diseases. As the war spread beyond Europe, many soldiers were infected with malaria and other exotic diseases. Although Lyme and other tick-borne diseases were not recognized at the time, they probably added to the list of WWI infectious diseases as well. Nearly 5 million had encephalitis lethargica during that time, a third of whom died; most of the survivors had significant neurological impairments. In Germany, 800,000 died from tuberculosis between 1914 and 1920. Typhus—the greatest killer of mankind—reemerged in 1917, killed 3 million individuals (mainly in refugee camps), and was epidemic throughout the 1920s. Countless others became infected and died in prisoner-of-war and refugee camps during and following WWI.6 7
Towards the end of WWI, the Spanish Influenza epidemic expanded and went on to infect 500 million—one-fifth of the world’s population—and kill 50 million (a death toll higher than that caused by the Black Death in the Middle Ages). Furthermore, the Spanish influenza epidemic killed almost three times more individuals than the 10 million soldiers and 6 million civilians who were killed during WWI
. The death, disability, and impairments caused by these infections probably added to the economic stressors contributing to WWII as well.
This raises an important question: How many of the 450 million who recovered from Spanish flu or other WWI-associated infections had residual neurological impairments that increased their risk for violence?