Measles sickened troops on both sides of the American Civil War.
“During the first year of war there were 21,676 reported cases of measles and 551 deaths in the Union Army alone. Deaths were primarily from respiratory and cerebral (brain) involvement. It was recorded, ‘This infection is always serious, often fatal either directly or through its sequelae. The Prognosis therefore should be guarded.'
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“The American Civil War was the last large-scale military conflict fought before the germ theory of disease was developed… Two-thirds of soldiers who died in that war, 660,000 in all, were killed by uncontrolled infectious diseases. Of these, in the Union Army over 67,000 had measles and more than 4,000 died.”