Smallpox one-third of the cases resulted in blindness. These deaths included those of four reigning monarchs and a queen consort. In the 20th century smallpox killed 200-300 million people. Edward Jenner discovered in 1798 that vaccination could prevent smallpox. In 1967, the WHO intensified efforts to eliminate the disease. Smallpox is one of two infectious diseases to have been eradicated, the other being rinderpest in 2011. The term "smallpox" was first used in Britain in the 15th century to distinguish the disease from syphilis, which was then known as the "great pox". Other historical names for the disease include pox, speckled
Smallpox the United States and South Africa a much milder form of smallpox, "variola minor", was recognized just before the close of the 19th century. By the mid-20th century "variola minor" occurred along with "variola major", in varying proportions, in many parts of Africa. Patients with "variola minor" experience only a mild systemic illness, are often ambulant throughout the course of the disease, and are therefore able to more easily spread disease. Infection with "v. minor" induces immunity against the more deadly "variola major" form. Thus as "v. minor" spread all over the USA, into Canada, the South American countries and