Disease
Contagious redirects here. For the Isley Brothers song of that name, see Contagious (song).A
disease is an abnormal condition of the
body or
mind that causes
discomfort,
dysfunction, or distress to the person afflicted or those in contact with the person. A condition that may result in the concerned person who suffers from it not behaving in a way that is natural for his species or his nature. Sometimes the term is used broadly to include injuries, disabilities,
syndromes, infections, symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts these may be considered distinguishable categories.
Pathology is the study of diseases. The subject of systematic classification of diseases is referred to as
nosology. The broader body of knowledge about human diseases and their treatments is
medicine. Many similar (and a few of the same) conditions or processes can affect animals (wild or domestic). The study of diseases affecting animals is
veterinary medicine. Plants as well can suffer from a variety of processes such as infection, nutrient deficiency, or deleterious mutation. The study of diseases affecting plants is termed
plant pathology.
Medical usage sometimes distinguishes a
disease, which has a known specific cause or causes (called its
etiology), from a
syndrome, which is a collection of signs or
symptoms that occur together. However, many conditions have been identified, yet continue to be referred to as "syndromes". Furthermore, numerous conditions of unknown etiology are referred to as "diseases" in many contexts.
Illness, although often used to mean disease, can also refer to a person's
perception of their health, regardless of whether they in fact have a disease. A person without any disease may feel unhealthy and believe he has an illness. Another person may feel healthy and believe he does not have an illness even though he may have a disease such as dangerously
high blood pressure which may lead to a fatal
heart attack or
stroke.
Disease can be thought of as the presence of pathology, which can occur with or without subjective feelings of being unwell or social recognition of that state; Illness as the subjective state of "unwellness", which can occur independently of, or in conjunction with disease or sickness; and sickness as the social classification of someone deemed diseased, which can also occur independently of the presence or absence of disease or illness. So someone with undetected high blood pressure who feels well would be diseased, but not ill or sick. Someone with a diagnosis of late-stage cancer would be diseased, probably feeling quite ill, and recognized by others as sick. A person incarcerated in a totalitarian psychiatric hospital for political purposes could arguably be then said to not be diseased, nor ill, but only classified as sick by the rulers of a society with which the person did not agree. Having had a bad day after a night of excess, one might feel ill, but you would not be diseased, nor is it likely you could convince your boss to recognize you as sick.
Sickness confers the social legitimization of certain benefits, such as illness benefit, work avoidance and being looked after by others. In return, there is an obligation on the sick person to seek treatment and work to become well once more.
Some diseases, such as
influenza, are contagious or
infectious, and can be transmitted by any of a variety of mechanisms, including
aerosols produced by coughs and sneezes, by bites of insects or other carriers of the disease, from contaminated water or food, etc.
Other diseases, such as
cancer and
heart disease are not considered to be due to infection, although micro-organisms may play a role, and cannot be spread from person to person.
The identification of a condition as a disease, rather than as simply a variation of human structure or function, can have significant social or economic implications. The controversial recognitions as diseases of
post-traumatic stress disorder, also known as "Soldier's heart," "shell shock," and "combat fatigue";
repetitive motion injury or
repetitive stress injury (RSI); and
Gulf War syndrome has had a number of positive and negative effects on the financial and other responsibilities of governments, corporations and institutions towards individuals, as well as on the individuals themselves. The social implication of viewing
aging as a disease could be profound, though this classification is not yet widespread.
A condition may be considered to be a disease in some cultures or eras but not in others.
Oppositional-defiant disorder,
attention-deficit hyperactivity disorder, and, increasingly,
obesity are conditions considered to be diseases in the United States and Canada today, but were not so-considered decades ago and are not so-considered in some other countries.
Lepers were a group of afflicted individuals who were historically shunned and the term "leper" still evokes social stigma. Fear of disease can still be a widespread social phenomena, though not all diseases evoke extreme social stigma.
A disease can also be caused by repeated high anger or stress.
In
biology,
disease refers to any abnormal condition of an organism that impairs function.
The term
disease is often used metaphorically for disordered, dysfunctional, or distressing conditions of other things, as in
disease of society.
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List of childhood diseases*
List of eponymous diseases*
List of common diseases*
List of diseases for a list of 6000+ diseases, many very rare.
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List of genetic disorders*
List of environment topics*
List of ICD-9 codes*
List of songs about disease*
List of infectious diseases *
Diagnosis*
Disease management (health)*
Epidemic*
Illness*
Palliative care*
Therapy*
Transmission*
Health Topics,
MedlinePlus descriptions of most diseases, with access to current research articles.
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Center for Disease Control Health Topics A-Z, fact sheets about many common diseases
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Medical Research News by Disease From ScienceDaily
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Rare/Orphan Diseases*
imedblog, Latest disease and medical news
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National Organization for Rare Disorders Extensive, useful information on rare diseases.
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The Merck Manual, detailed description of most diseases, freely searchable online.
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MDmaker Diseases, A list of some common diseases.
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Sign and Disease*
Medical disease report writer Create your own medical report based on information from the web
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Infection Protection: How to Fight the Germs That Make You Sick*
Infection Protection: Pandemic
