Causes of Human Disease: Understanding Causes of Disease

Disease is now understood to have natural, not supernatural, causes. As Hippocrates observed, illness arises from earthly influences. Modern medicine groups disease causes into categories such as infections, genetics, lifestyle, environment, and nutrition. In practice, most illnesses result from complex interactions between these factors—for example, host immunity and pathogen virulence. This review highlights each major cause with common examples and key research findings.