Mozart and smallpox the imperial family were successful, and led to greater public acceptance for the procedure. Smallpox struck the Mozart family again in the next generation: Nannerl's eldest son Leopold and two of her stepchildren caught the disease during an outbreak in the Salzburg area in 1787. All three children survived. In 1796, the discovery of vaccination—the use of the related cowpox virus to immunize against smallpox—by Edward Jenner revolutionized the ability of medicine to deal with smallpox. Vaccination reached Vienna around 1800, when yet another local epidemic created impetus for its adoption. One of the doctors trained in the Vienna campaign,
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