Final answer:
Jon Snow's research established that cholera was transmitted through contaminated water, leading to progressive public health measures and reinforcing the germ theory of disease. His investigation mapped the spread of cholera and identified unsanitary water as the outbreak's source, with his findings guiding modern epidemiology.
Step-by-step explanation:
The major finding of Jon Snow's research was that cholera was transmitted through drinking water contaminated with sewage. Snow debunked the prevalent miasma theory, which ascribed the transmission of diseases to airborne vapors, instead suggesting that cholera spread via a fecal-oral route.
By mapping the incidences of cholera and identifying the contaminated Broad Street water pump as their epicenter, Snow advised local authorities to remove the pump handle, effectively containing the epidemic and demonstrating the importance of sanitary practices.
His studies during the 1848 and 1854 cholera epidemics in London led to advancements in public health responses and the understanding of disease transmission, supporting the later-accepted germ theory of disease.
Snow's methodology in studying the spread of disease through case-tracking and the creation of point maps prefigures modern-day epidemiological techniques and Geographic Information System (GIS) applications.
Moreover, Dr. Snow's investigations demonstrated that water from the Thames downstream of sewage dumping was a conduit for the illness, while brewery workers who drank beer instead of water did not contract cholera.