Who is often considered the first epidemiologist?

• A. Hippocrates
• B. Louis Pasteur
• C. Robert Koch
• D. John Snow

Answer: (A)

The trend in epidemiology starts with looking at how disease varies across populations, not just in individuals. Hippocrates, writing in ancient Greece, began linking disease frequency to environmental factors, geography, and seasons, shifting thinking from superstition to population-based observation. This approach laid the groundwork for epidemiology as the study of disease patterns in groups, which is why he’s often considered the earliest epidemiologist.

Later figures like John Snow are celebrated for applying careful data collection and natural experiments to pinpoint disease sources, and Pasteur and Koch are key for advancing germ theory. But Hippocrates represents the earliest step in epidemiologic thinking—the idea that studying how disease distributes across places and times can reveal important truths about health.