agostino bassi al-andalus atharvaveda bacillus anthracis bacteria beauveria bassiana black death bubonic plague cholera contagious contemporary reaction to ignaz semmelweis francesco redi girolamo fracastoro heredity hungary hygiene ibn al-khatib ignaz semmelweis immune system infectious disease lifestyle louis pasteur marcus terentius varro miasma miasma theory of disease microbiology microorganism nutrition public health puerperal fever quarantine reproduction robert koch rudolf virchow secretion socioeconomics status the canon of medicine the islamic medical association of north america theory tuberculosis vienna general hospital