Final answer:
Health agencies use review of medical records and interviews with selected patients by epidemiologists to gather data on disease incidence for public health surveillance and intervention strategies.
Step-by-step explanation:
Health agencies collect data on the incidence of diseases through various methods, which are key to public health surveillance and policy-making. One approach includes reviewing medical records to identify patterns and categories related to disease cases, such as methods of transmission or risk factors labeled as Methods A, B, and C, and others. Additionally, epidemiologists conduct interviews with a randomly selected sample of patients to gather more detailed information that might not be captured in medical records, such as patient behaviors or potential sources of infection.
For instance, the data provided from Santa Clara County regarding the 3,059 documented cases of a disease could help determine if a particular method of transmission is more prevalent, thereby allowing public health officials to develop targeted intervention strategies to control the spread. These efforts are crucial for the assessment and implementation of effective public health policies and emergency response procedures.