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All About Epidemiology



Epidemiology is the study of why and how often diseases occur in different groups of people. An epidemiologist is a scientist who studies the causes, transmission, and outbreak of diseases. They are often called “disease detectives.”


  • Epidemiologists manage studies about various diseases. Their work pertains to pandemics such as COVID-19, but also to isolated and unrelated diseases affecting a population.
  • The main difference between a doctor and an epidemiologist is that a doctor focuses on the health of individuals, and an epidemiologist focuses on the health of groups of people.
  • Epidemiology includes the study of both epidemics and pandemics. When a disease occurs in a high number of people in an area, it is called an epidemic. When a disease occurs in a high number of people and over multiple countries or continents, it is called a pandemic.
  • Epidemiologists do a lot of research in laboratories and collecting data. Their goal is to learn how the outbreak can be stopped. They oversee medications such as vaccines and study their effectiveness.
  • The word “epidemiology” comes from a Greek word that means “the study of what is upon the people.”
  • Besides the spread of diseases, epidemiology also involves the study of the frequency of health-related conditions in a population, like high blood pressure and obesity.
  • The Greek physician Hippocrates, who lived around 400 BCE, is considered the first person who studied where diseases come from and how they spread.
  • A man named John Snow is considered the “father of epidemiology.” In the mid-1800s, he studied an outbreak of cholera and made a map marking the residence of everyone who had cholera in an area of London. He knew that understanding the spread of diseases better would help prevent future outbreaks.



Outbreak: A sudden beginning of something unwanted, like disease, or war.

Cholera: An infection of the small intestine caused by unsafe, contaminated water and food.


Questions and Answers

Question: How important is epidemiology?


Answer: Epidemiology is very important for the health of people all over the world. We need “disease detectives” to help control the spread of diseases and prevent future outbreaks.


Learn more about John Snow and the cholera outbreak in London in 1854.