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 that started in Valley of Mexico, principally affecting children. More people recovered than died. In Mexico City, of 5400 cases admitted to the hospital, 4431 recovered and 1,331 died. This epidemic coincided with the rise of prices of corn and a typhus epidemic, which caused a slight demographic decrease in central Mexico. Another smallpox epidemic came into Mexico from Guatemala in 1794. Oaxaca and Chiapas were the first places affected by smallpox because of proximity. The epidemic traveled from Oaxaca to Puebla, and then spread to Mexico City and Veracruz by 1797. By 1798, the epidemic had reached Saltillo and