View source for Disease

{{mergefrom|Illness|date=May 2010}}
{{redirect|Medical condition|medical condition terminology|Medical state}}
{{other uses}}
{{pp-move-indef|small=yes}}
[[File:Mycobacterium tuberculosis.jpg|thumb|[[Scanning electron micrograph]] of ''[[Mycobacterium tuberculosis]]'', an infectious [[pathogenic bacteria]] that is the primary cause of [[Tuberculosis]]]]
A '''disease'''  i.e LUCAS TAYLOR .  is an abnormal condition affecting the body of a homosexual [[organism]]. It is often construed to be a '''medical condition''' associated with specific [[symptom]]s and [[Medical sign|sign]]s.<ref>{{DorlandsDict|three/000030493|Disease}}</ref> It may be caused by external factors, such as [[infectious disease]], or it may be caused by internal dysfunctions, such as [[autoimmune disease]]s. In humans, "disease" is often used more broadly to refer to any condition that causes [[pain]], [[Abnormality (behavior)|dysfunction]], [[distress (medicine)|distress]], [[social problems]], or [[death]] to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes [[injury|injuries]], [[disability|disabilities]], [[disorder (medicine)|disorder]]s, [[syndrome]]s, [[infection]]s, isolated [[symptom]]s, deviant [[behavior]]s, and atypical [[human variability|variation]]s of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. 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 their personality.

Death due to disease is called [[death by natural causes]]. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease. 

Diseases can also be classified as communicable and non-communicable disease.

==Terminology==
===Concepts===
In many cases, the terms ''disease'', ''disorder'', ''morbidity'' and ''illness'' are used interchangeably.<ref>{{cite web |url=http://science.education.nih.gov/supplements/nih5/mental/other/glossary.htm |title=Mental Illness—Glossary |publisher=US [[National Institute of Mental Health]] |date= |accessdate=2010-04-18}}</ref>  In some situations, specific terms are considered preferable.

;Disease
:The term ''disease'' broadly refers to any condition that impairs normal function, and is always associated with dysfunction of normal homeostasis.  Commonly, term ''disease'' is used to refer specifically to [[infectious disease]]s, 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 [[prion]]s.  An [[infection]] that does not and will not produce clinically evident impairment of normal functioning, such as the presence of the normal [[gut flora|bacteria and yeasts in the gut]], is not considered a disease; by contrast, an infection that is asymptomatic during its [[incubation period]], but expected to produce symptoms later, is usually considered a disease.  [[Non-infectious disease]]s are all other diseases, including most forms of [[cancer]], [[heart disease]], and [[genetic disease]].
;Illness
:''[[Illness]]'' and ''sickness'' are generally used as synonyms for ''disease''.<ref>{{DorlandsDict|four/000052397|Illness}}</ref> However, this term is occasionally used to refer specifically to the patient's personal experience of their disease.<ref name="pmid3567788">{{cite journal |author=Emson HE |title=Health, disease and illness: matters for definition |journal=[[CMAJ]] |volume=136 |issue=8 |pages=811–3 |year=1987 |month=April |pmid=3567788 |pmc=1492114 }}</ref><ref name="pmid3567791">{{cite journal |author=McWhinney IR |title=Health and disease: problems of definition |journal=CMAJ |volume=136 |issue=8 |page=815 |year=1987 |month=April |pmid=3567791 |pmc=1492121 }}</ref>  In this model, it is possible for a person to be diseased without being ill (to have an objectively definable, but asymptomatic, medical condition), and to be ''ill'' without being ''diseased'' (such as when a person perceives a normal experience as a medical condition, or [[medicalization|medicalizes]] a non-disease situation in his or her life). Illness is often not due to infection but a collection of [[evolutionary medicine|evolved responses]], [[sickness behavior]], by the body which aids the clearing of infection. Such aspects of illness can include [[lethargy]], [[depression (mood)|depression]], [[anorexia (symptom)|anorexia]], [[sleepiness]], [[hyperalgesia]], and inability to [[Attention|concentrate]].<ref name="Hart">{{cite journal |author=Hart BL |year=1988 |title=Biological basis of the behavior of sick animals |journal=[[Neurosci Biobehav Rev]] |volume=12 |issue=2 |pages=123–137 |pmid=3050629 |doi=10.1016/S0149-7634(88)80004-6}}</ref><ref>{{cite journal |author=Johnson R |year=2002 |title=The concept of sickness behavior: a brief chronological account of four key discoveries |journal=[[Veterinary Immunology and Immunopathology]] |volume=87 |issue=3–4 |pages=443–450 |pmid=12072271 |doi=10.1016/S0165-2427(02)00069-7}}</ref><ref>{{cite journal |author=Kelley KW, Bluthe RM, Dantzer R, Zhou JH, Shen WH, Johnson RW, Broussard SR |year=2003 |title=Cytokine-induced sickness behavior |journal=[[Brain Behav Immun]] |volume=17 |issue=Suppl 1 |pages=S112–118 |pmid=12615196 |doi=10.1016/S0889-1591(02)00077-6}}</ref>
;Disorder
:In medicine, a '''disorder''' is a functional abnormality or disturbance.  Medical disorders can be categorized into [[mental disorder]]s, [[physical disorder]]s, [[genetic disorder]]s, [[emotional and behavioral disorders]], and [[functional disorder]]s.  The term ''disorder'' is often considered more value-neutral and less stigmatizing than the terms ''disease'' or ''illness'', and therefore is preferred terminology in some circumstances.  In mental health, the term [[mental disorder]] is used as a way of acknowledging the complex interaction of [[Biopsychosocial model|biological, social, and psychological factors]] in [[psychiatric]] conditions.  However, the term ''disorder'' is also used in many other areas of medicine, primarily to identify physical disorders that are not caused by infectious organisms, such as [[metabolic disorder]]s.
;Medical condition
: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. The [[Diagnostic and Statistical Manual of Mental Disorders]] (DSM), the widely used psychiatric manual that defines all [[mental disorder]]s, uses the term ''general medical condition'' to refer to all diseases, illnesses, and injuries except for [[mental disorder]]s.<ref>{{cite book |publisher=American Psychiatric Association |year=2000 |title=Diagnostic and statistical manual of mental disorders |edition=4th |location=Washington, DC |author=American Psychiatric Association. Task Force on DSM-IV |isbn=978-0-89042-025-6 }}</ref> This usage is also commonly seen in the psychiatric literature. Some [[health insurance]] policies also define a ''medical condition'' as any illness, injury, or disease except for psychiatric illnesses.<ref>{{cite web |url=http://www.theinsurancepage.co.uk/expat-insurance-glossary.html |title=Expat Insurance Glossary by The Insurance Page |accessdate=2008-11-20}}</ref>
:As it is more [[value-neutral]] than terms like ''disease'', the term ''medical condition'' is sometimes preferred by people with health issues that they do not consider to be deleterious.  On the other hand, by emphasizing the medical nature of the condition, this term is sometimes rejected, such as by proponents of the [[autism rights movement]]. 
:The term ''medical condition'' is also used as a synonym for [[medical state]], in which case it describes an individual patient's current state, as seen from a medical standpoint.  This usage is seen in statements that describe a patient as being "in critical condition", for example.
;{{Visible anchor|Morbidity}}
:'''Morbidity''' ({{ety|la|morbidus|sick, unhealthy}}) is a diseased state, disability, or poor health due to any cause.<ref>[http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/five/000067536.htm ''Dorland's Medical Dictionary'': morbidity], ''[[Dorland's medical reference works|Dorland's Medical Dictionary]]'', ''MerckSource''</ref>  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.  Among severely ill patients, the level of morbidity is often measured by [[ICU scoring systems]].  [[Comorbidity]] is the simultaneous presence of two or more medical conditions, such as [[schizophrenia]] and [[substance abuse]].
:In [[epidemiology]] and [[actuarial science]], the term [[morbidity rate]] can refer to either the [[incidence (epidemiology)|incidence]] rate, or the [[prevalence]] of a disease or medical condition. This measure of sickness is contrasted with the [[mortality rate]] of a condition, which is the proportion of people dying during a given time interval.
;Syndrome
:A [[syndrome]] is the association of several [[medical sign]]s, [[symptom]]s, and or other characteristics that often occur together.  Some syndromes, such as [[Down syndrome]], have only one cause; others, such as [[Parkinsonian syndrome]], have multiple possible causes. In other cases, the cause of the syndrome is unknown.  A familiar syndrome name often continues to be used even after an underlying cause has been found, or when there are a number of different possible primary causes.
;Predisease
:'''Predisease''' is a type of [[disease creep]] or [[medicalization]] in which currently healthy people with [[risk factor]]s for disease, but no evidence of actual disease, are told that they are sick.  [[Prediabetes]] and [[prehypertension]] are common examples.  Labeling a healthy person with predisease can result in [[overtreatment]], such as taking drugs that only help people with severe disease, or in useful preventive measures, such as motivating the person to get a healthful amount of physical exercise.<ref name="Lenzer">{{cite news
|url=http://www.slate.com/articles/health_and_science/medical_examiner/2012/08/blood_pressure_drugs_for_mild_hypertension_not_proven_to_prevent_heart_attacks_strokes_or_early_death.single.html
|title=Blood pressure drugs for mild hypertension: Not proven to prevent heart attacks, strokes, or early death - Slate Magazine
|last=Lenzer
|first=Jeanne
|date=14 August 2012
|work=[[Slate (magazine)|Slate]]
|accessdate=16 August 2012}}</ref>

===Types===
;Infectious diseases
;Contagious diseases
;Communicable diseases
;Non-communicable diseases
;Airborne diseases
;Lifestyle diseases

===Stages===
{{redirect|Flareup|the Transformers character|Flareup (Transformers)}}
In an infectious disease, the [[incubation period]] is the time between infection and the appearance of symptoms.  The [[latency period]] is the time between infection and the ability of the disease to spread to another person, which may precede, follow, or be simultaneous with the appearance of symptoms.  Some viruses also exhibit a dormant phase, called [[viral latency]], in which the virus hides in the body in an inactive state.  For example, [[varicella zoster virus]] causes [[chickenpox]] in the [[acute (medicine)|acute phase]]; after recovery from chickenpox, the virus may remain dormant in nerve cells for many years, and later cause [[herpes zoster]] (shingles).

;Acute disease
:An [[acute disease]] is a short-lived disease, like the [[common cold]].
;Chronic disease
: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 (medicine)|remission]] and periodically [[relapse]].  A chronic disease may be stable (does not get any worse) or it may be progressive (gets worse over time).  Some chronic diseases can be permanently cured.  Most chronic diseases can be beneficially treated, even if they cannot be permanently cured.
;Flare-up
:A flare-up can refer to either the recurrence of symptoms or an onset of more severe symptoms.
;Refractory disease
: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
:[[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 disease]]s; many are also [[degenerative disease]]s.  The opposite of progressive disease is ''stable disease'' or ''static disease'':  a medical condition that exists, but does not get better or worse.
;Cure
:A [[cure]] is the end of a medical condition or a treatment that is very likely to end it, while [[Cure#Remission|remission]] refers to the disappearance, possibly temporarily, of symptoms.  Complete remission is the best possible outcome for incurable diseases.

===Scope===
;Localized disease
:A [[localized disease]] is one that affects only one part of the body, such as [[athlete's foot]] or an [[eye infection]].
;Disseminated disease
:A [[disseminated disease]] has spread to other parts; with cancer, this is usually called [[metastatic disease]].
;Systemic disease
:A [[systemic disease]] is a disease that affects the entire body, such as [[influenza]] or [[hypertension|high blood pressure]].

==Causes and transmissibility==
{{Main|Transmission (medicine)}}
Only some diseases such as [[influenza]] are contagious and commonly believed to be infectious. The micro-organisms that cause these diseases are known as pathogens and include varieties of bacteria, viruses, protozoa and fungi. [[Infectious disease]]s can be transmitted, e.g. by hand-to-mouth contact with infectious material on surfaces, by bites of [[vector (epidemiology)|insects or other carriers]] of the disease, and from contaminated water or food (often via [[faeces|faecal]] contamination), etc. In addition, there are [[sexually transmitted diseases]]. In some cases, [[micro-organisms]] that are not readily spread from person to person play a role, while other diseases can be prevented or ameliorated with appropriate [[nutrition]] or other lifestyle changes.  

Some diseases, such as most (but not all) forms of [[cancer]], [[heart disease]] and mental disorders, are [[non-infectious disease]]s. Many non-infectious diseases have a partly or completely genetic basis (see [[genetic disorder]]) and may thus be transmitted from one generation to another.

[[Social determinants of health]] are the social conditions in which people live which determine their health. Illnesses are generally related to social, economic, political, and [[Environmental disease|environmental circumstances]]. Social determinants of health have been recognized by several health organizations such as the Public Health Agency of [[Canada]] and the World Health Organization to greatly influence collective and personal well-being. The World Health Organization's Social Determinants Council also recognizes [[Social determinants of health in poverty]]. 

When the cause of a disease is poorly understood, societies tend to mythologize the disease or use it as a [[metaphor]] or symbol of whatever that culture considers to be evil.  For example, until the bacterial cause of [[tuberculosis]] was discovered in 1882, experts variously ascribed the disease to [[hereditary disease|heredity]], a [[sedentary lifestyle]], [[depression (mood)|depressed mood]], and overindulgence in sex, rich food, or alcohol—all the [[social ills]] of the time.<ref>{{cite book |author=Olson, James Stuart |title=Bathsheba's breast: women, cancer & history |publisher=The Johns Hopkins University Press |location=Baltimore |year=2002 |pages=168–170 |isbn=0-8018-6936-6 }}</ref>

==Burdens of disease==
[[Disease burden]] is the impact of a health problem in an area measured by financial cost, mortality, morbidity, or other indicators.

There are several measures used to quantify the burden imposed by diseases on people.  The [[years of potential life lost]] (YPLL) is a simple estimate of the number of years that a person's life was shortened due to a disease.  For example, if a person dies at the age of 65 from a disease, and would probably have lived until age 80 without that disease, then that disease has caused a loss of 15 years of potential life.  YPLL measurements do not account for how disabled a person is before dying, so the measurement treats a person who dies suddenly and a person who died at the same age after decades of illness as equivalent.  In 2004, the [[World Health Organization]] calculated that 932 million years of potential life were lost to premature death.<ref name=WHODALY />

The [[quality-adjusted life year]] (QALY) and [[disability-adjusted life year]] (DALY) metrics are similar, but take into account whether the person was healthy after diagnosis.  In addition to the number of years lost due to premature death, these measurements add part of the years lost to being sick.  Unlike YPLL, these measurements show the burden imposed on people who are very sick, but who live a normal lifespan.  A disease that has high morbidity, but low mortality, will have a high DALY and a low YPLL.  In 2004, the World Health Organization calculated that 1.5 billion disability-adjusted life years were lost to disease and injury.<ref name=WHODALY>:{{cite web |publisher=World Health Organization|url=http://www.who.int/healthinfo/global_burden_disease/estimates_regional/en/index.html |title=Disease and injury regional estimates for 2004}} 
:Standard DALYs (3% discounting, age weights).
:[http://www.who.int/entity/healthinfo/global_burden_disease/DALY14_2004.xls DALY spreadsheet]
:[http://www.who.int/entity/healthinfo/global_burden_disease/YLL14_2004.xls YLL spreadsheet].</ref>

{| class="wikitable sortable"
|-
! Disease category
! scope="col" width=10% | Percent of all YPLLs lost, worldwide<ref name=WHODALY />
! scope="col" width=10% | Percent of all DALYs lost, worldwide<ref name=WHODALY />
! scope="col" width=10% | Percent of all YPLLs lost, Europe<ref name=WHODALY />
! scope="col" width=10% | Percent of all DALYs lost, Europe<ref name=WHODALY />
! scope="col" width=10% | Percent of all YPLLs lost, US and Canada<ref name=WHODALY />
! scope="col" width=10% | Percent of all DALYs lost, US and Canada<ref name=WHODALY />
|-
| Infectious and parasitic diseases, especially [[lower respiratory tract infection]]s, [[diarrhea]], [[AIDS]], [[tuberculosis]], and [[malaria]]
| 37%
| 26%
| 9%
| 6%
| 5%
| 3%
|-
| [[Neuropsychiatric conditions]], e.g. [[major depressive disorder|depression]]
| 2%
| 13%
| 3%
| 19%
| 5%
| 28%
|-
| [[Injuries]], especially [[motor vehicle accidents]]
| 14%
| 12%
| 18%
| 13%
| 18%
| 10%
|-
| [[Cardiovascular disease]]s, principally [[heart attacks]] and [[stroke]]
| 14%
| 10%
| 35%
| 23%
| 26%
| 14%
|-
| [[Premature birth]] and other [[perinatal]] deaths
| 11%
| 8%
| 4%
| 2%
| 3%
| 2%
|-
| [[Cancer]]
| 8%
| 5%
| 19%
| 11%
| 25%
| 13%
|}

==Prevention==
{{Main|Preventive medicine}}

Many diseases and disorders can be prevented through a variety of means.  These include [[sanitation]], proper [[nutrition]], adequate [[exercise]], [[vaccination]]s, and other [[self-care]] and [[public health]] measures.

==Treatments==
{{Main|Therapy}}
Medical therapies or treatments are efforts to cure or improve a disease or other health problem.  In the medical field, therapy is synonymous with the word ''treatment''.  Among psychologists, the term may refer specifically to [[psychotherapy]] or "talk therapy".  Common treatments include [[medication]]s, [[surgery]], [[medical devices]], and [[self-care]].  Treatments may be provided by an organized [[health care system]], or informally, by the patient or family members.

A [[Preventive medicine|prevention or preventive therapy]] is a way to avoid an injury, sickness, or disease in the first place.  A treatment or cure is applied after a medical problem has already started.  A treatment attempts to improve or remove a problem, but treatments may not produce permanent cures, especially in [[chronic diseases]].  [[Cure]]s are a subset of treatments that reverse diseases completely or end medical problems permanently.  Many diseases that cannot be completely cured are still treatable. [[Pain management]] (also called pain medicine) is that branch of medicine employing an interdisciplinary approach to the relief of pain and improvement in the quality of life of those living with pain<ref>{{cite book |title=Chronic Pain Management: The Essentials |author=Hardy, Paul A.; Hardy, Paul A. J. |page=10 |year=1997 |publisher=Cambridge University Press |isbn=978-1-900151-85-6 |url=http://books.google.com/books?id=EtZ-4eb_aDUC&pg=PA10&lpg=PA10 |oclc=36881282}}</ref>

Treatment for [[medical emergencies]] must be provided promptly, often through an [[emergency department]] or, in less critical situations, through an [[urgent care]] facility.

==Epidemiology==
{{Main|Epidemiology}}
Epidemiology is the study of the factors that cause or encourage diseases.  Some diseases are more common in certain geographic areas, among people with certain genetic or socioeconomic characteristics, or at different times of the year.

Epidemiology is considered a cornerstone methodology of public health research, and is highly regarded in [[evidence-based medicine]] for identifying [[risk factor]]s for disease. In the study of communicable and non-communicable diseases, the work of epidemiologists ranges from [[outbreak]] investigation to study design, data collection and analysis including the development of statistical models to test hypotheses and the documentation of results for submission to peer-reviewed journals. Epidemiologists also study the interaction of diseases in a population, a condition known as a [[syndemic]]. Epidemiologists rely on a number of other scientific disciplines such as [[biology]] (to better understand disease processes), [[biostatistics]] (the current raw information available), [[Geographic Information Science]] (to store data and map disease patterns) and [[social science]] disciplines (to better understand proximate and distal risk factors).

In studying diseases, epidemiology faces the challenge of defining them.  Especially for poorly understood diseases, different groups might use significantly different definitions.  Without an agreed-upon definition, different researchers will find very different numbers of cases and characteristics of the disease.<ref>{{cite news
| url = http://www.nytimes.com/2011/03/08/health/research/08fatigue.html
| title = Defining an illness is fodder for debate
| author = Tuller, David
| newspaper = The New York Times
| date = 4 March 2011}}</ref>

==Social and cultural responses==
[[File:Italienischer Maler des 17. Jahrhunderts 001.jpg|thumb|upright|[[Obesity]] was a status symbol in [[Renaissance]] culture: "The Tuscan General [[Alessandro del Borro]]", attributed to [[Andrea Sacchi]], 1645.<ref>{{cite web |url=http://www.cab.u-szeged.hu/cgfa/m/m-12.htm | author=Carol Gerten-Jackson | title=The Tuscan General Alessandro del Borro}}</ref> It is now generally regarded as a disease.]]

How a society responds to diseases is the subject of [[medical sociology]]. 

A condition may be considered to be a disease in some cultures or eras but not in others.  For example, [[obesity]] can represent wealth and abundance, and is a status symbol in famine-prone areas and some places hard-hit by [[AIDS wasting|HIV/AIDS]].<ref name=HaslamJames>{{cite journal |author=Haslam DW, James WP |title=Obesity |journal=Lancet |volume=366 |issue=9492 |pages=1197–209|year=2005 |pmid=16198769 |doi=10.1016/S0140-6736(05)67483-1}}</ref>  [[Epilepsy]] is considered a sign of spiritual gifts among the [[Hmong people]].<ref>{{cite book |author=Fadiman, Anne |title=The spirit catches you and you fall down: a Hmong child, her American doctors, and the collision of two cultures |publisher=Farrar, Straus, and Giroux |location=New York |year=1997|isbn=0-374-52564-1 |oclc= }}</ref>

Sickness confers the social legitimization of certain benefits, such as illness benefits, work avoidance, and being looked after by others.  The person who is sick takes on a social role called the [[sick role]].  A person who responds to a dreaded disease, such as [[cancer survivor|cancer]], in a culturally acceptable fashion may be publicly and privately honored with higher [[social status]].<ref>{{cite book | author=Sulik, Gayle | title=Pink Ribbon Blues: How Breast Cancer Culture Undermines Women's Health |publisher=Oxford University Press | location=New York | year=2010 | isbn=0-19-974045-3}}</ref>  In return for these benefits, the sick person is obligated to seek treatment and work to become well once more.  As a comparison, consider [[pregnancy]], which is not interpreted as a disease or sickness, even if the mother and baby may both benefit from medical care.  

Most religions grant exceptions from religious duties to people who are sick. For example, one whose life would be endangered by  [[fasting]] on [[Yom Kippur]] or during [[Ramadan]] is exempted from the requirement, or even forbidden from participating.  People who are sick are also exempted from social duties.  For example, ill health is the only socially acceptable reason for an American to refuse an invitation to the [[White House]].<ref>{{cite book
|author=Martin, Judith
|title=Miss Manners' Guide to Excruciatingly Correct Behavior
|publisher=W.W. Norton & Co
|location=New York
|year=2005
|pages=703
|isbn=978-0-393-05874-1
|oclc=57549405 }}</ref>

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 [[repetitive stress injury]] (RSI) and [[post-traumatic stress disorder]] (also known as "[[Da Costa's syndrome|Soldier's heart]]", "[[shell shock]]", and "combat fatigue") 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 [[senescence|aging]] as a disease could be profound, though this classification is not yet widespread.  

[[Leprosy|Lepers]] were people who were historically shunned because they had an infectious disease, and the term "leper" still evokes [[social stigma]]. Fear of disease can still be a widespread social phenomenon, though not all diseases evoke extreme social stigma.

Social standing and economic status affect health.  [[Diseases of poverty]] are diseases that are associated with [[poverty]] and low social status; [[diseases of affluence]] are diseases that are associated with high social and economic status.  Which diseases are associated with which states varies according to time, place, and technology.  Some diseases, such as [[diabetes mellitus]], may be associated with both poverty (poor food choices) and affluence (long lifespans and sedentary lifestyles), through different mechanisms.  The term [[diseases of civilization]] describes diseases that are more common among older people.  For example, [[cancer]] is far more common in societies in which most members live until they reach the age of 80 than in societies in which most members die before they reach the age of 50.

===Language of disease===

An [[illness narrative]] is a way of organizing a medical experience into a coherent story that illustrates the sick individual's personal experience.

People use [[metaphor]]s to make sense of their experiences with disease.  The metaphors move disease from an objective thing that exists to an [[affective]] experience.  The most popular metaphors draw on [[military]] concepts:  Disease is an enemy that must be feared, fought, battled, and routed.  The patient or the healthcare provider is a warrior, rather than a passive victim or bystander. The agents of communicable diseases are invaders; non-communicable diseases constitute internal insurrection or civil war.  Because the threat is urgent, perhaps a matter of life and death, unthinkably radical, even oppressive, measures are society's and the patient's moral duty as they courageously mobilize to struggle against destruction.  The [[War on Cancer]] is an example of this metaphorical use of language.<ref name=Gwyn>{{cite book
|author=Gwyn, Richard
|editor=Cameron, Lynne; Low, Graham
|others=
|title=Researching and applying metaphor
|publisher=Cambridge University Press
|location=Cambridge, England
|year=1999
|chapter=10
|isbn=978-0-521-64964-3 
|oclc=40881885 }}</ref>

Another class of metaphors describes the experience of illness as a journey:  The person travels to or from a place of disease, and changes himself, discovers new information, or increases his experience along the way.  He may travel "on the road to recovery" or make changes to "get on the right track".<ref name=Gwyn /> Some are explicitly immigration-themed:  the patient has been exiled from the home territory of health to the land of the ill, changing identity and relationships in the process.<ref name=Diedrich>{{cite book
|author=Diedrich, Lisa
|title=Treatments: language, politics, and the culture of illness
|publisher=University of Minnesota Press
|location=Minneapolis
|year=2007
|pages=8, 29
|isbn=978-0-8166-4697-5
|oclc=601862594 }}</ref>

Some metaphors are disease-specific.  [[Slavery]] is a common metaphor for [[addiction]]s:  The alcoholic is enslaved by drink, and the smoker is captive to nicotine.  Some cancer patients treat the loss of their hair from [[chemotherapy]] as a [[metonymy]] or metaphor for all the losses caused by the disease.<ref name=Gwyn />  

Some diseases are used as metaphors for social ills:  "Cancer" is a common description for anything that is endemic and destructive in society, such as poverty, injustice, or racism.  AIDS was seen as a divine judgment for moral decadence, and only by purging itself from the "pollution" of the "invader" could society become healthy again.<ref name=Gwyn />  Authors in the 19th century [[Tuberculosis in popular culture|commonly used tuberculosis]] as a symbol and a metaphor for [[Transcendence (religion)|transcendence]].  Victims of the disease were portrayed in literature as having risen above daily life to become ephemeral objects of spiritual or artistic achievement.  In the 20th century, after its cause was better understood, the same disease became the emblem of poverty, squalor, and other social problems.<ref name=Diedrich />

==See also==
{{Portal|medicine}}
* [[Airborne disease]], a disease that spreads through the air
* [[Contagious disease]], a subset of infectious diseases
* [[Cryptogenic disease]], a disease whose cause is currently unknown
* [[Environmental disease]]
* [[Lifestyle disease]], a disease caused largely by lifestyle choices
* [[Non-communicable disease]], a disease that can't be spread between people
* [[Organic disease]]
* [[Plant pathology]]
* [[Rare disease]], a disease that affects very few people
* [[Sociology of health and illness]]
* [[List of acronyms on diseases and disorders]]
* [[List of cutaneous conditions]]
* [[Lists of diseases]]
* [[List of human diseases associated with infectious pathogens]]
* [[List of mystery diseases]]

==References==
{{reflist|colwidth=30em}}

==External links==
{{Commons category|Diseases and disorders|diseases}}
{{wikiquote}}
{{Wiktionary|disease}}
*[http://www.nlm.nih.gov/medlineplus/healthtopics.html Health Topics], [[MedlinePlus]] descriptions of most diseases, with access to current research articles.
*[http://www.ncbi.nlm.nih.gov/omim/ OMIM] Comprehensive information on genes that cause disease at [[Online Mendelian Inheritance in Man]]
*[http://ctdbase.org/ CTD] The [[Comparative Toxicogenomics Database]] is a scientific resource connecting chemicals, genes, and human diseases.
*[http://www.nlm.gov/ NLM] Comprehensive database from the [[US National Library of Medicine]]
*[http://www.cdc.gov/health/default.htm Health Topics A-Z], fact sheets about many common diseases at [[Centers for Disease Control]]
*[http://www.merck.com/pubs/mmanual/sections.htm The Merck Manual] containing detailed description of most diseases
*[http://www.who.int/healthinfo/global_burden_disease/2004_report_update/en/index.html Report: ''The global burden of disease''] from [[World Health Organization]] (WHO), 2004
*[http://www.yourdiseaserisk.wustl.edu Free online health-risk assessment] by [[Your Disease Risk]] at Washington University in St Louis

{{Medical terms to describe disease conditions}}
{{Pathology}}
{{Medical conditions}}

[[Category:Diseases and disorders| ]]
[[Category:Actuarial science]]
[[Category:Demography]]
[[Category:Epidemiology]]
[[Category:Medical terms]]
[[Category:Medicine]]
[[Category:Social problems]]

[[ang:Ādl]]
[[ar:مرض]]
[[an:Malautía]]
[[arc:ܟܘܪܗܢܐ]]
[[ast:Enfermedá]]
[[gn:Mba'asy]]
[[ay:Usu]]
[[az:Xəstəlik]]
[[bm:Banaw]]
[[bn:রোগ]]
[[bjn:Garing]]
[[zh-min-nan:Pīⁿ]]
[[map-bms:Penyakit]]
[[be:Хвароба]]
[[be-x-old:Хвароба]]
[[bg:Болест]]
[[bo:ན་ཚ།]]
[[bs:Bolest]]
[[br:Kleñved]]
[[ca:Malaltia]]
[[cs:Nemoc]]
[[cy:Clefyd]]
[[da:Sygdom]]
[[de:Krankheit]]
[[et:Haigus]]
[[el:Ασθένεια]]
[[myv:Ормат]]
[[es:Enfermedad]]
[[eo:Malsano]]
[[ext:Malotia]]
[[eu:Eritasun]]
[[fa:بیماری]]
[[fr:Maladie]]
[[fy:Sykte]]
[[ga:Galar]]
[[gl:Doenza]]
[[gan:病]]
[[ko:질병]]
[[hy:Հիվանդություն]]
[[hi:रोग]]
[[hr:Bolest]]
[[io:Morbo]]
[[id:Penyakit]]
[[ia:Maladia]]
[[is:Sjúkdómur]]
[[it:Malattia]]
[[he:מחלה]]
[[jv:Panyakit]]
[[ka:დაავადება]]
[[kk:Дерт]]
[[ht:Maladi]]
[[ku:Nesaxî]]
[[ky:Оору]]
[[la:Morbus]]
[[lv:Slimība]]
[[lt:Liga]]
[[li:Krenkde]]
[[ln:Bokɔnɔ]]
[[hu:Betegség]]
[[mk:Болест]]
[[mg:Marary]]
[[ml:രോഗം]]
[[mr:रोग]]
[[ms:Penyakit]]
[[nah:Cocoliztli]]
[[nl:Ziekte]]
[[ne:रोग]]
[[ja:病気]]
[[no:Sykdom]]
[[nn:Sjukdom]]
[[oc:Malautiá]]
[[pnb:روگ]]
[[ps:ناروغي]]
[[pl:Choroba]]
[[pt:Doença]]
[[ro:Boală]]
[[qu:Unquy]]
[[rue:Хворота]]
[[ru:Болезнь]]
[[sah:Ыарыы]]
[[sq:Sëmundja]]
[[scn:Affizzioni]]
[[si:රෝග]]
[[simple:Disease]]
[[sk:Choroba]]
[[sl:Bolezen]]
[[so:Cudur]]
[[sr:Болест]]
[[sh:Bolest]]
[[fi:Sairaus]]
[[sv:Sjukdom]]
[[tl:Karamdaman]]
[[ta:நோய்]]
[[te:వ్యాధి]]
[[th:โรค]]
[[tr:Hastalık]]
[[uk:Хвороба]]
[[ur:مرض]]
[[vi:Bệnh]]
[[fiu-vro:Tõbi]]
[[wa:Maladeye]]
[[war:Sakit]]
[[yi:קראנקייט]]
[[yo:Àrùn]]
[[bat-smg:Lėga]]
[[zh:疾病]]