How does the Centers for Disease Control and Prevention (CDC) know when there is a health risk to a population, and how is it notified?

The writing is about 1.How does the U.S. Department of Health and Human Services receive, transmit, and communicate health care data?
2. How does the Centers for Disease Control and Prevention (CDC) know when there is a health risk to a population, and how is it notified?
please edit/proofreading without plagiarism.