A structural or functional abnormality in the body in known as disease. A disease is an abnormal condition that affects the body of an organism.The term disease broadly refers to any condition that impairs normal function, and is therefore associated with dysfunction of normal homeostasis. It may be caused by factors originally from an external source, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune diseases. Diseases usually affect people not only physically, but also emotionally, as contracting and living with many diseases can alter one’s perspective on life, and one’s personality. Death due to disease is called natural death. There are four main categories of disease.
- Pathogenic disease
- Deficiency disease
- Hereditary disease
- Physiological disease
Common Terminology used instead of disease are disorder, morbidity and illness are used interchangeably. Commonly, the term disease is used to refer specifically to infectious diseases, which are clinically evident diseases that result from the presence of pathogenic microbial agents, including viruses, bacteria, fungi, protozoa, multicellular organisms, and aberrant proteins known as prions. Non-infectious diseases are all other diseases, including most forms of cancer, heart disease, and genetic disease. Illness and sickness are generally used as synonyms for disease. Illness is often not due to infection, but to a collection of evolved responses—sickness behaviour by the body—that helps clear infection. Such aspects of illness can include lethargy, depression, anorexia, sleepiness, and inability to concentrate. In medicine, a disorder is a functional abnormality or disturbance. Medical disorders can be categorized into mental disorders, physical disorders, genetic disorders, emotional and behavioural disorders, and functional disorders.
A medical condition is a broad term that includes all diseases and disorders. While the term medical condition generally includes mental illnesses, in some contexts the term is used specifically to denote any illness, injury, or disease except for mental illnesses. Morbidity is a diseased state, disability, or poor health due to any cause. The term may be used to refer to the existence of any form of disease, or to the degree that the health condition affects the patient. A syndrome is the association of several medical signs, symptoms, and or other characteristics that often occur together. Pre-disease is a type of disease creep or medicalization in which currently healthy people with risk factors for disease, but no evidence of actual disease, are told that they are sick.
Types of disease.
An acute disease is a short-lived disease, like the common cold.
A chronic disease is one that lasts for a long time, usually at least six months. During that time, it may be constantly present, or it may go into remission and periodically relapse.
A refractory disease is a disease that resists treatment, especially an individual case that resists treatment more than is normal for the specific disease in question.
Progressive disease is a disease whose typical natural course is the worsening of the disease until death, serious debility, or organ failure occurs. Slowly progressive diseases are also chronic diseases; many are also degenerative diseases. The opposite of progressive disease is stable disease or static disease: a medical condition that exists, but does not get better or worse.
A localized disease is one that affects only one part of the body, such as athlete’s foot or an eye infection.
A disseminated disease has spread to other parts; with cancer, this is usually called metastatic disease.
A systemic disease is a disease that affects the entire body, such as influenza or high blood pressure.