6.1: Introduction
Epidemiology is the study of diseases, health-states, and health outcomes. Epidemiologists are especially interested in how diseases and conditions are distributed throughout populations, and finding those factors that increase or decrease the risk of a particular disease - or in fact actually cause the disease or condition. The word “epidemiology” comes from the Greek word “epidemia”, which means the “prevalence of a disease”. So naturally those studying diseases have a lot of questions, such as:
- Does a disease affect one population more than another? Do the number of people affected increase or decrease over time?
- What are the associations between biological factors, exposures to pathogens or toxins, the environment, and behaviors that could influence disease states and health outcomes?
- Are there ways to increase the average lifespan and make those years healthy and enjoyable?
- Can we still identify and stop a disease or condition from hurting more people even if we don’t know the exact cause?
All of these questions - and others - spark the curiosity of someone interested in epidemiology. Historically, epidemiology was first used to help identify causes and risk factors for infectious diseases. This is still an essential role for epidemiologists around the world, especially as we experience new and re-emerging contagious diseases. However, chronic diseases, behavioral health problems, injuries, and violence are now also studied using epidemiology techniques. In this chapter, we’ll go over some of the basic tools that epidemiologists use to understand health problems, and potentially how to solve them.