Final answer:
An epidemic is a large-scale disease outbreak that affects an unusually high number of individuals in a population at the same time and is more extensive than expected. It is studied by epidemiologists and differs from a pandemic, which is a global epidemic affecting multiple locations.
Step-by-step explanation:
An epidemic refers to a disease that occurs in an unusually high number of individuals in a population at the same time. It's more extensive than expected for a given population. For instance, if there's a sudden rise in cases of influenza in a particular region during a specific period, and the number exceeds what's typically observed, this could be classified as an epidemic.
Such occurrences are studied by epidemiologists, who examine how diseases affect populations. It's important to distinguish an epidemic from a pandemic, which is an outbreak of a disease that becomes widespread and affects multiple populations across continents, or even worldwide. Pandemics are large-scale epidemics that have significant impact due to their reach.
Many infectious diseases have caused both epidemics and pandemics throughout history, such as the Black Death and the more recent HIV/AIDS epidemic, which became a pandemic. Understanding the difference between these terms is essential for public health and epidemiology.