Ten thousand years ago, when smallpox first emerged, humankind could do little more than pray to the gods for succor. Later known as variola, the virus that caused the disease first attacked the linings of the nose or throat, spreading throughout the body until a characteristic rash followed by virus-filled blisters developed on the skin. Over the course of recorded history, the “speckled monster” killed up to a third of the people it infected. During the 20th century alone, it felled more than 300 million men, women and children.
By the late 1970s, however, the deadly scourge had been eliminated from the face of the earth thanks to mass vaccination campaigns that protected millions and left them with a small scar on their upper arm. With nowhere to hide in the natural world—humans are the virus's only host—variola was beaten into extinction. Today the only known viral samples are locked in two specialized government laboratories, one in the U.S. and the other in Russia. Absent a catastrophic lab accident, deliberate release or the genetic reengineering of the virus, smallpox will never again spread death and misery across the globe.