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
1974 smallpox epidemic in India the last cases of smallpox, called "Target Zero", with the identification of the last smallpox patient in India occurring on May 24, 1975. By 1980, smallpox was certified as being eradicated from the world. Smallpox was eradicated due to the WHO's smallpox eradication program. This program was formally established in 1958, but because of logistics disagreements between the WHO and the Indian government, did not progress rapidly. Headway only began to take place in India after the reorganization of the WHO in the mid 1960s. Donald Henderson, who was a U.S. Public Health Services Officer stationed in New Delhi, said