John Snow: Cholera

John Snow's approach to explaining cholera and how it spread consisted primarily of morbid poison entering the alimentary canal through means of contaminated water consumption. Snow believed this to be the basis of how cholera was contracted by individuals and believed improper sewage filtration was to blame as well as a means of spreading the disease from person to person. However, previous explanations of how cholera was contracted consisted of the theory of airborne infection. This theory proposed that cholera was contracted by inhaling air at low levels of altitude by such people as workers in slaughterhouses and bone merchants. This theory also proposed that the foul-smelling odors associated with these occupations were closely correlated with transmission. Having had previous knowledge of respiratory physiology, Snow dismissed the idea of cholera spreading by means of airborne infection because it had no relevance of what he already knew of inhalant anesthetics. Snow backed up his position by pointing out that if inhaling air in a workplace such as a slaughterhouse were the means in which the transmission of cholera occurred, then the workers in them would be primary targets in contracting the disease. Since this was not the case, Snow continued to stick with his theory of cholera being transmitted by swallowing "morbid matter" specific to the disease. (Snow) Snow further attempted to prove his theory of waterborne transmission of cholera by conducting studies in various London sub districts in August of 1848. In this study he found that homes whose water was supplied to them by the Lambeth Water Company had few incidents of cholera, whereas homes whose water was supplied to them by the Southwark and Vauxhall Water Company had high incidences of cholera. Snow concluded that the reasons for various cholera incidents involving different water companies had to do with where the companies drew their water supply. Snow believed Lambeth Water