What is the definition of an epidemic?

The definition of an epidemic is a widespread occurrence of an infectious disease in a specific area, which aligns with the correct choice. An epidemic typically refers to a situation in which the number of cases of a disease exceeds what is normally expected in that population or area within a given timeframe. This heightened incidence can be localized, affecting a community or region, and is generally associated with a sudden increase in cases that can significantly impact public health.

In contrast, other definitions describe different phenomena. A disease that is prevalent worldwide is not an epidemic but rather classified as a pandemic, indicating a much broader scope of impact. The description of diseases spreading specifically through food refers to foodborne illnesses, which is a more focused circumstance rather than encompassing the broader definition of an epidemic. Finally, identifying a situation with only one case of a disease does not fit the definition of an epidemic, as it emphasizes a singular occurrence rather than an increase in cases that defines an epidemic situation. Thus, the correct answer accurately captures the essence of what an epidemic is within the context of infectious diseases.