Communicable diseases are illnesses caused by infectious agents such as bacteria, viruses, fungi, parasites, or other microorganisms that can be transmitted from one person to another, from animals to humans, or through the environment. These diseases are also known as infectious or transmissible diseases because they spread through various modes of transmission. In the context of health emergencies and disaster management, communicable diseases are considered major threats because outbreaks can occur rapidly, affect large populations, and create significant challenges for healthcare systems. The concept of communicable diseases is based on the interaction between an infectious agent, a susceptible host, and a suitable environment. This relationship is often referred to as the epidemiological triad. The infectious agent is the organism responsible for causing the disease, while the host is the individual who can become infected due to factors such as age, immunity, nutrition, and health status. The environment