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
History of smallpox in Mexico caused Viceroy Félix Calleja to take preventive measures like fumigations and vaccination, which were successful. There were sporadic outbreaks until 1826 when smallpox appeared in Yucatán, Tabasco and Veracruz brought by North American ships. In 1828, there were reported cases in Hidalgo, Oaxaca, State of Mexico, Guerrero, Chiapas, Chihuahua and Mexico City. Efforts to eradicate smallpox in Mexico started with Dr José Ignacio Bartolache who wrote a book in 1779 about smallpox called “Instrucción que puede servir para que se cure a los enfermos de las viruelas epidemicas que ahora se padecen en México”(Instructions that may help to cure smallpox