What term describes diseases that reappear after being under control or appearing in new regions?

• A. Emerging diseases
• B. Endemic diseases
• C. Re-emerging diseases
• D. Eradicated diseases

Answer: (C)

Re-emerging diseases describe infections that come back after a period of control or appear in new regions. This label fits when a disease that was previously under better control increases in incidence again, or spreads to populations or areas where it was not present before. It’s different from emerging diseases, which are newly appearing or previously unknown to humans, and from endemic diseases, which are consistently present in a region. It’s also distinct from eradicated diseases, which have been globally eliminated. Factors driving re-emergence include waning immunity or gaps in vaccination, antimicrobial resistance, changes in vectors or ecosystems, climate and land-use changes, and increased movement of people and goods. Examples include outbreaks of measles when vaccination coverage drops and the reappearance or spread of diseases like dengue in new regions.