A disease is an abnormal condition that adversely affects the structure or function of all or part of an organism and is not immediately caused by external injury. It is typically associated with specific signs and symptoms and can result from external factors like pathogens or internal dysfunctions such as immune system problems
. Diseases impair the normal functioning of the body or mind, causing pain, dysfunction, distress, or death
. Diseases can be infectious (caused by microbes like bacteria, viruses, fungi) or non-infectious (such as genetic disorders, cancer, or heart disease)
. They may be acute (short-term) or chronic (long-lasting)
. The study of disease, called pathology, involves understanding their causes, development, and effects on the body
. In medical terms, a disease is a diagnosable disorder that interferes with normal bodily functions and can be identified through medical history, exams, and tests
. It differs from "illness," which refers more to the subjective experience of feeling unwell
. In summary, a disease is a harmful deviation from normal health that disrupts an organism's normal structure or function, often with identifiable symptoms and causes
