John Snow, Cholera, the Broad Street Pump; Waterborne Diseases Then and Now

Cholera was a major global scourge in the 19(th) century, with frequent large-scale epidemics in European cities primarily originating in the Indian subcontinent. John Snow conducted pioneering investigations on cholera epidemics in England and particularly in London in 1854 in which he demonstrated that contaminated water was the key source of the epidemics. His thorough investigation of an epidemic in the Soho district of London led to his conclusion that contaminated water from the Broad Street pump was the source of the disease and, consequently, the removal of the handle led to cessation of the epidemic. He further studied cholera in London homes that were receiving water from two water supply systems; one from the sewage contaminated portion of the Thames River and the other that drew its water upstream from an uncontaminated part of the river. Rates of infection among clients of the distribution system drawing contaminated water far exceeded the, rates among those served by the company whose water intake was from above the contaminated section of the river. This demonstration reinforced the goals of the sanitation movement, which developed sewage drainage systems and water purification systems in cities and towns in the following decades, therewith vastly reducing the threats of cholera, typhoid and many other waterborne diseases. Despite progress being made globally, the public health problems of waterborne disease, including cholera, are by no means gone today, even in high-income countries. The tragic introduction of cholera after the earthquake devastation in Haiti in 2010 resulted in many thousands of cases and deaths from cholera indicating the still-present dangers of diseases spread into disaster situations. Cholera and other waterborne diseases remain some of the heaviest burdens of disease and death in low-income countries, especially after natural disasters or warfare as in Yemen in 2017 and are continuing challenges for global health.