Final answer:
An emerging infectious disease (EID) is a new disease that is appearing for the first time in human populations or has significantly increased in prevalence. Surveillance is essential in controlling infectious diseases at the community level through monitoring and tracking the occurrence and spread of diseases.
Step-by-step explanation:
An emerging infectious disease (EID) refers to a new disease that is appearing for the first time in human populations or has significantly increased in prevalence over the past 20 years. EIDs can emerge when previously harmless microorganisms evolve to become pathogenic to humans or when microorganisms that infect nonhuman animals jump to human hosts. Surveillance plays a crucial role in controlling infectious diseases at the community level, as it involves monitoring and tracking the occurrence and spread of diseases, allowing for early detection and response.