Final answer:
The 19th Century cholera epidemic in London was caused by fecal contamination of the water supply. Dr. John Snow's research and removal of the Broad Street pump's handle greatly reduced the incidence of the disease. Improved sanitation and water quality regulation stemmed from this public health crisis.
Step-by-step explanation:
The cholera epidemic in 19th Century London was primarily caused by the contamination of the water supply by fecal material. Dr. John Snow's investigation during the 1854 cholera outbreak in London was a pivotal moment in public health and epidemiology. By creating a detailed map of cholera deaths and linking them to the water source at the Broad Street pump, which was contaminated by sewage, he was able to convince local authorities to remove the handle of the pump. This intervention significantly reduced the spread of the disease, refuting the then-dominant miasma theory that diseases like cholera were spread through bad air.
Poor urban planning, lack of proper sewage disposal, and polluted drinking water, due to poor sanitation, were the main causes of cholera outbreaks. The public health response, sparked by Snow's findings, resulted in an improvement in water quality regulations and infrastructure, reducing the impact of the disease. This approach of linking cholera to a contaminated water source became a landmark in scientific reasoning and laid the foundation for modern epidemiology and sanitation practices.