Virology in order to immunize others. In 1717 Lady Mary Wortley Montagu observed the practice in Istanbul and attempted to popularize it in Britain, but encountered considerable resistance. In 1796 Edward Jenner developed a much safer method, using cowpox to successfully immunize a young boy against smallpox, and this practice was widely adopted. Vaccinations against other viral diseases followed, including the successful rabies vaccination by Louis Pasteur in 1886. The nature of viruses however was not clear to these researchers. In 1892, the Russian biologist Dmitry Ivanovsky used a Chamberland filter to try to isolate the bacteria that caused tobacco mosaic
Donald Henderson United States Agency for International Development (USAID) program to eliminate smallpox and control measles during a 5-year period in 18 contiguous countries in western and central Africa. This project was funded by USAID, with field operations beginning in 1967. The USAID initiative provided an important impetus to a World Health Organization (WHO) program to eradicate smallpox throughout the world within a 10-year period. In 1966, Henderson moved to Geneva to become director of the campaign. At that time, smallpox was occurring widely throughout Brazil and in 30 countries in Africa and South Asia. More than 10 million cases and 2