Communicable diseases: Illnesses that can be transmitted from one person or animal to another, or from an animal to a person. They are caused by infectious agents.

Here are the definitions for the terms related to disease progression:

• Communicable diseases: Illnesses that can be transmitted from one person or animal to another, or from an animal to a person. They are caused by infectious agents.
• Non-communicable diseases: Chronic diseases that are not transmitted from person to person. They are often long-lasting and result from a combination of genetic, physiological, environmental, and behavioral factors.
• Causative organism/agent: The specific pathogen (e.g., bacterium, virus, fungus, parasite) that causes a disease.
• Vector: An organism, typically an arthropod (like a mosquito or tick), that transmits a disease-causing pathogen from one host to another.
• Microorganisms: Microscopic organisms, such as bacteria, viruses, fungi, and protozoa, some of which can cause disease.
• Virulence: The degree of pathogenicity of a microorganism, indicating its ability to cause disease.
• Mutate: To undergo a change in genetic material (DNA or RNA), which can lead to new characteristics in an organism, such as increased resistance to drugs or altered virulence.
• Infectivity: The ability of a pathogen to invade and multiply in a host, leading to infection.
• Commensal: A microorganism that lives in or on a host without causing harm, and sometimes providing benefit.
• Disease: A disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury.