Smallpox is a viral disease (poxvirus variola) that produces pimple-like pustulates on the skin. The scars that are left behind are ugly pock-marks, or divots, in the skin. That's where the name pox comes from. The [incubation period] is from nine to twelve days. [Inoculations] for smallpox were first used in the 1600's in China. Dust scraped from smallpox scabs was blown into someone's nose, infecting them and making them immune. Edward Jenner invented the first [vaccine] by taking cowpox and injecting it into the blood. In 1979, the World Health Organization (WHO) announced that smallpox had been wiped out completely. The WHO will destroy the last stockpile of the virus on June 30, 1999.
Edward Jenner giving smallpox vaccine (1802)
After incubation period: The first symptoms are a high fever of 106 degrees, chills, backaches, and headaches.
Four days later: This stage produces temporary relief, but rash appears on face, chest, arms, back, and legs.
Next few days: In this stage, the spots change to raised, blister-like pustules, or variola (from varius, or spotted).
After nine days: In this stage, the pustulates split open, dry
up, and form scabs, which fall off and leave scars. If the virus
attacks the eyes, lungs, throat, heart, and liver, it can lead to
Vaccine fact sheet