John Snow's 1849 recommendation that water be "filtered and boiled before it is used" is one of the first practical applications of the
germ theory of disease in the area of public health and is the antecedent to the modern boil water advisory. Snow demonstrated a clear understanding of germ theory in his writings. He first published his theory in an 1849 essay
On the Mode of Communication of Cholera, in which he correctly suggested that the fecal-oral route was the mode of communication, and that the disease replicated itself in the lower intestines. Snow later went so far as to accurately propose in his 1855 edition of the work that the structure of cholera was that of a cell. Snow's ideas were not fully accepted until years after his death in 1858. The first known modern boil-water advisory based solely on
germ theory and unfettered by extraneous and irrelevant advice was distributed in 1866 during
the last of three major cholera outbreaks that ravaged London in the 19th century. == Recent instances ==