IMMUNOLOGY

Detailed explanation-1: -Communicable diseases, also known as infectious diseases or transmissible diseases, are illnesses that result from the infection, presence and growth of pathogenic (capable of causing disease) biologic agents in an individual human or other animal host.

Detailed explanation-2: -Some-but not all-infectious diseases spread directly from one person to another. Infectious diseases that spread from person to person are said to be contagious. Some infections spread to people from an animal or insect, but are not contagious from another human.

Detailed explanation-3: -Infectious diseases are disorders caused by organisms-such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies.

Detailed explanation-4: -Communicable diseases are transmitted from an infected person to a healthy person via air, water, food, or direct contact. Examples: Common cold, Cholera, Chickenpox, Tuberculosis.