Which statement defines endemic in epidemiology?

• A. Is habitually present in human populations
• B. Occurs clearly in excess of normal expectancy
• C. Affects a large number of countries simultaneously
• D. Exhibits a seasonal pattern

Answer: (A)

Endemic means a disease is habitually present in a population or area at a relatively stable level over time. This describes the ongoing, expected presence of the disease rather than sudden, unusual surges. The other ideas point to different patterns: an epidemic or outbreak is a surge above the normal level; a pandemic involves widespread transmission across many countries; a seasonal pattern refers to recurring timing but doesn’t define steady, baseline presence. So the statement that best captures endemic is that the disease is habitually present in the population.