When referring to a disease, “endemic” describes the constant presence and/or usual prevalence of a disease or infectious agent within a specific geographic area or population group. Endemic diseases are those that persistently exist in a particular region or population without the need for external inputs or new introductions.

Factors contributing to the endemicity of a disease may include environmental conditions, host susceptibility, and the presence of vectors or reservoirs for the infectious agent. Endemic diseases may fluctuate in intensity over time but remain consistently present in the defined area or population.

Examples of endemic diseases include malaria in certain regions of Africa, Chagas disease in parts of Latin America, and dengue fever in various tropical and subtropical areas. The term “endemic” is often used in contrast to “epidemic” and “pandemic,” which describe sudden increases in the occurrence of a disease within a specific population or across multiple regions, respectively.