Transmitted by human vectors rather than by insects or contaminated water, the variola virus typically caused influenza-like symptoms twelve days after exposure; three or four days later, the first sores erupted, often in the mouth and throat, before spreading to the palms, soles, face, torso, forearms, nostrils, and eyes. By the fourth week, mortality might range from 15 to 60 percent. Survivors—like Washington and Montgomery—were scarred for life and sometimes blinded, though perpetually immune; pocked young men were much prized by military recruiters.
