Communicable Disease Overview

Preventing and mitigating the spread of disease is a foundational area of public health. Communicable disease prevention and control is important because it keeps people healthy, saves lives, protects those most at risk, reduces healthcare costs, and helps communities, schools, businesses, and other societal systems function effectively. It also ensures communities are better prepared to respond to future disease outbreaks and public health emergencies.

Communicable diseases are illnesses caused by infectious agents (e.g.: viruses, bacteria, fungi, or parasites) that can be transmitted directly or indirectly between people, animals, or through the environment (Centers for Disease Control and Prevention, 2024a). Examples include influenza, COVID-19, tuberculosis, and measles.

Noncommunicable diseases (NCDs) are generally known as chronic diseases (WHO, 2025). They are not caused by infectious agents and are not transmitted from person to person. They often develop over time and may be influenced by genetics, behaviors, environmental exposures, and social and economic conditions. Examples include heart disease, cancer, diabetes, and chronic respiratory diseases.