Natural History and Spectrum of Disease
This book on Principles of Epidemiology in Public Health Practice from the CDC will help you understand the natural history of disease.
Read Section 1 pages 59-61
Click https://drive.google.com/file/d/1Gxw89XSx7ZwSaPJfaihdVfj5WGaO2y63/view?usp=drive_link link to open resource.