The definition “The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems.” The discussion This definition shows that epidemiology is a scientific approach used to study diseases and other health problems in communities. The definition also talks about distribution, which refers to how disease is spread within a population in terms of person, place, and time. This means epidemiology studies who is affected, where the disease is common, and when it occurs most frequently. For example, during a cholera outbreak, the disease may affect mostly people living in overcrowded communities with poor sanitation, especially during the rainy season. Another important aspect in the definition is determinants. Determinants are the factors that influence the occurrence of disease. In the cholera example, contaminated water, poor hygiene, and poor environmental sanitation are determinants responsible for the outbreak. The definition further includes health-related states or events, showing that epidemiology is not limited to communicable diseases alone. It also studies accidents, malnutrition, maternal deaths, disabilities, and other conditions affecting public health. John Last also mentioned specified populations, which means epidemiology studies diseases in groups of people rather than in one individual person. This helps identify the pattern and burden of disease within a community. Finally, the application of epidemiology is directed toward the control of health problems. After identifying the causes and distribution of cholera, measures such as provision of clean water, proper waste disposal, and health education can be introduced to control the outbreak.