Which statement about John Snow is accurate?

• A. He demonstrated that cholera transmission was linked to contaminated water and pump handles.
• B. He developed the first vaccine for cholera.
• C. He discovered the cause of malaria.
• D. He introduced antiseptic surgery techniques.

Answer: (A)

Understanding John Snow’s contribution helps you grasp how epidemiology began to identify how diseases spread. During a cholera outbreak in London in 1854, Snow carefully mapped who was getting sick and where they lived, and he noticed a strong pattern around the Broad Street water pump. He argued that the illness came from contaminated drinking water, not from some mysterious “bad air.” When he advised removing the pump handle, the outbreak subsided, which provided powerful evidence that cholera could be transmitted through water and that public health actions based on data could prevent disease. This approach—observing, analyzing patterns, and acting on findings—is a cornerstone of public health practice. The other statements don’t fit Snow’s work: he did not develop a cholera vaccine, he did not discover the cause of malaria, and he did not introduce antiseptic surgery techniques.