Disease

sexually transmitted disease

pathogen: tác nhân gây bệnh

immunodeficiency: sự suy giảm hệ miễn dịch

hypersensitivity: sự quá mẫn cảm với một thứ gì đó, dẫn đến dị ứng

an infectious disease can be passed easily from one person to another, especially through the air they breathe

if a person or an animal is infectious, they have a disease that can be spread to others

Diseases can also be classified as communicable (lây truyền được) and non-communicable.

contagion [U] the spreading of a disease by people touching each other

acquired (adj) gotten through environmental forces

coronary artery disease (blood flow obstruction): bệnh động mạch vành= atherosclerosis

cerebrovascular disease (mạch máu nảo) and

lower respiratory infections: nhiễm trùng đường hô hấp dưới

trauma: a deeply distressing or disturbing experience

~~~~

 

Disease

A disease is a particular abnormal condition, a disorder of a structure or function, that affects part or all of an organism. The study of disease is called pathology which includes the causal study of etiology. Disease is often construed as a medical condition associated with specific symptoms and signs.[1] It may be caused by external factors such as pathogens, or it may be caused by internal dysfunctions particularly of the immune system such as an immunodeficiency, or a hypersensitivity including allergies and autoimmunity.

In humans, disease is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or deathto the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries,disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases can affect people not only physically, but also emotionally, as contracting and living with a disease can alter the affected person’s perspective on life.

Death due to disease is called death by natural causes. There are four main types of disease: infectious diseases, deficiency diseases, genetic diseases both (hereditary and non-hereditary), and physiological diseases. Diseases can also be classified as communicable and non-communicable. The deadliest diseases in humans are coronary artery disease (blood flow obstruction), followed by cerebrovascular disease and lower respiratory infections.[2]

Terminology[edit]

Concepts[edit]

In many cases, terms such as disease, disorder, morbidity and illness are used interchangeably.[3] There are situations, however, when specific terms are considered preferable.

Disease
The term disease broadly refers to any condition that impairs the normal functioning of the body. For this reason, diseases are associated with dysfunctioning of the body’s normal homeostatic processes (các quá trình cân bằng nội môi).[4] The term disease has both a count sense (a disease, two diseases, many diseases) and a noncount sense (not much disease, less disease, a lot of disease). Commonly, the term 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. An infection that does not and will not produce clinically evident impairment of normal functioning, such as the presence of the normal bacteria and yeasts in the gut, or of a passenger virus, 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 diseases are all other diseases, including most forms of cancer[citation needed], heart disease, and genetic disease.
Acquired disease 
disease that began at some point during one’s lifetime, as opposed to disease that was already present at birth, which is congenital disease. “Acquired” sounds like it could mean “caught via contagion“, but it simply means acquired sometime after birth. It also sounds like it could imply secondary disease, but acquired disease can be primary disease.
Acute disease 
disease of a short-term nature (acute); the term sometimes also connotes a fulminant nature
Chronic disease
disease that is a long-term issue (chronic)
Congenital disease
disease that is present at birth. It is often, genetic and can be inherited. It can also be the result of a vertically transmitted infection from the mother such as HIV/AIDS.
Genetic disease
disease that is caused by genetic mutation. It is often inherited, but some mutations are random and de novo.
Hereditary or inherited disease
a type of genetic disease caused by mutation that is hereditary (and can run in families)
Idiopathic disease
disease whose cause is unknown. As medical science has advanced, many diseases whose causes were formerly complete mysteries have been somewhat explained (for example, when it was realized that autoimmunity is the cause of some forms of diabetes mellitus type 1, even if we do not yet understand every molecular detail involved) or even extensively explained (for example, when it was realized that gastric ulcers are often associated with Helicobacter pylori infection).
Incurable disease
disease that cannot be cured
Primary disease
disease that came about as a root cause of illness, as opposed to secondary disease, which is a sequela of another disease
Secondary disease
disease that is a sequela or complication of some other disease or underlying cause (root cause). Bacterial infections can be either primary (healthy but then bacteria arrived) or secondary to a viral infection or burn, which predisposed by creating an open wound or weakened immunity (bacteria would not have gotten established otherwise).
Terminal disease
disease with death as an inevitable result
Illness
Illness is generally used as a synonym for disease.[5] However, this term is occasionally used to refer specifically to the patient’s personal experience of his or her disease.[6][7]In this model, it is possible for a person to have a disease without being ill (to have an objectively definable, but asymptomatic, medical condition, such as a subclinical infection), and to be ill without being diseased (such as when a person perceives a normal experience as a medical condition, or medicalizes a non-disease situation in his or her life – for example, a person who feels unwell as a result of embarrassment, and who interprets those feelings as sickness rather than normal emotions). Symptoms of illness are often not directly the result of infection, but a collection of evolved responsessickness behavior by the body—that helps clear infection. Such aspects of illness can include lethargy, depression, loss of appetite, sleepiness, hyperalgesia, and inability to concentrate.[8][9][10]
Disorder
In medicine, a disorder is a functional abnormality or disturbance. Medical disorders can be categorized into mental disorders, physical disorders, genetic disorders,emotional and behavioral disorders, and functional disorders. The term disorder is often considered more value-neutral and less stigmatizing than the terms disease or illness, and therefore is a preferred terminology in some circumstances.[11] In mental health, the term mental disorder is used as a way of acknowledging the complex interaction ofbiological, 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 disorders.
Medical condition
A medical condition is a broad term that includes all diseases, lesions, disorders, or nonpathologic condition that normally receives medical treatment, such as pregnancy orchildbirth. 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 disorders, uses the term general medical condition to refer to all diseases, illnesses, and injuries except for mental disorders.[12] 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.[13]
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 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 a synonym for medical state, in which case it describes an individual patient’s current state from a medical standpoint. This usage appears in statements that describe a patient as being in critical condition, for example.
Morbidity
Morbidity (from Latin morbidus, meaning “sick, unhealthy”) is a diseased state, disability, or poor health due to any cause.[14] 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 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 signs, symptoms, and or other characteristics that often occur together. Some syndromes, such as Down syndrome, have only one cause; for these, the names “syndrome” and “disease” can be synonymous. For example, Charcot–Marie–Tooth syndrome is also called Charcot–Marie–Tooth disease. Others, such as Parkinsonian syndrome, have multiple possible causes. For example, acute coronary syndrome is not a disease but rather the manifestation of any of several diseases, such as myocardial infarction secondary to coronary artery disease. In yet other syndromes, the cause is unknown. A familiar syndrome name often remains in use even after an underlying cause has been found, or when there are a number of different possible primary causes.
Predisease
Predisease is a subclinical or prodromal vanguard of a disease state. Prediabetes and prehypertension are common examples. The nosology or epistemology of predisease is contentious, though, because there is seldom a bright line differentiating a legitimate concern for subclinical/prodromal/premonitory status (on one hand) and conflict of interest–driven disease mongering or medicalization (on the other hand). Identifying legitimate predisease can result in useful preventive measures, such as motivating the person to get a healthy amount of physical exercise,[15] but labeling a healthy person with an unfounded notion of predisease can result in overtreatment, such as taking drugs that only help people with severe disease or paying for drug prescription instances whose benefit–cost ratio is minuscule (placing it in the waste category of CMS‘s “waste, fraud, and abuse” classification).

Types by body system[edit]

Mental
Mental illness is a broad, generic label for a category of illnesses that may include affective or emotional instability, behavioral dysregulation, cognitive dysfunction or impairment. Specific illnesses known as mental illnesses include major depression, generalized anxiety disorders, schizophrenia, and attention deficit hyperactivity disorder, to name a few. Mental illness can be of biological (e.g., anatomical, chemical, or genetic) or psychological (e.g., trauma or conflict) origin. It can impair the affected person’s ability to work or study and can harm interpersonal relationships. The term insanity is used technically as a legal term.
Organic
An organic disease is one caused by a physical or physiological change to some tissue or organ of the body. The term sometimes excludes infections. It is commonly used in contrast with mental disorders. It includes emotional and behavioral disorders if they are due to changes to the physical structures or functioning of the body, such as after a stroke or a traumatic brain injury, but not if they are due to psychosocial issues.

Stages[edit]

“Flareup” redirects here. For the Transformers character, see 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 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 and periodicallyrelapse. 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 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.
Cure
A cure is the end of a medical condition or a treatment that is very likely to end it, while remission refers to the disappearance, possibly temporarily, of symptoms. Complete remission is the best possible outcome for incurable diseases.
Clinical disease
One that has clinical consequences, i.e., the stage of the disease that produces the characteristic signs and symptoms of that disease.[16] AIDS is the clinical disease stage ofHIV infection.
Subclinical disease
Also called silent disease, silent stage, or asymptomatic disease. This is a stage in some diseases before the symptoms are first noted.[17]
Terminal phase
If a person will die soon from a disease, regardless of whether that disease typically causes death, then the stage between the earlier disease process and active dying is the terminal phase.

Extent[edit]

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 high blood pressure.

Classifications[edit]

Main article: nosology

Diseases may be classified by etiology (cause), pathogenesis (mechanism by which the disease is caused), or by symptom(s). Alternatively, diseases may be classified according to the organ system involved, though this is often complicated since many diseases affect more than one organ.

A chief difficulty in nosology is that diseases often cannot be defined and classified clearly, especially when etiology or pathogenesis are unknown. Thus diagnostic terms often only reflect a symptom or set of symptoms (syndrome).

Classical classification of human disease derives from observational correlation between pathological analysis and clinical syndromes. Today it is preferred to classify them by their etiology if it is known.[18]

The most known and used classification of diseases is the World Health Organization‘s ICD. This is periodically updated. Currently the last publication is the ICD-10

Causes[edit]

Only some diseases such as influenza are contagious and commonly believed infectious. The micro-organisms that cause these diseases are known as pathogens and include varieties of bacteria, viruses, protozoa and fungi. Infectious diseases can be transmitted, e.g. by hand-to-mouth contact with infectious material on surfaces, by bites of insects or other carriers of the disease, and from contaminated water or food (often via fecal contamination), etc.[19] In addition, there are sexually transmitted diseases. In some cases,microorganisms 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 diseases. 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 that determine their health. Illnesses are generally related to social, economic, political, andenvironmental 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 evil. For example, until the bacterial cause of tuberculosis was discovered in 1882, experts variously ascribed the disease to heredity, a sedentary lifestyle, depressed mood, and overindulgence in sex, rich food, or alcohol—all the social ills of the time.[20]

Types of causes[edit]

Airborne
An airborne disease is any disease that is caused by pathogens and transmitted through the air.
Infectious
Infectious diseases, also known as transmissible diseases or communicable diseases, comprise clinically evident illness (i.e., characteristic medical signs and/or symptoms of disease) resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism. Included in this category are contagious diseases – an infection, such as influenza or the common cold, that commonly spreads from one person to another – and communicable diseases – an disease that can spread from one person to another, but does not necessarily spread through everyday contact.
Non-communicable
A non-communicable disease is a medical condition or disease that is non-transmissible. Non-communicable diseases cannot be spread directly from one person to another.Heart disease and cancer are examples of non-communicable diseases in humans.
Foodborne
Foodborne illness or food poisoning is any illness resulting from the consumption of food contaminated with pathogenic bacteria, toxins, viruses, prions or parasites.
Lifestyle
A lifestyle disease is any disease that appears to increase in frequency as countries become more industrialized and people live longer, especially if the risk factors include behavioral choices like a sedentary lifestyle or a diet high in unhealthful foods such as refined carbohydrates, trans fats, or alcoholic beverages.

Prevention[edit]

Main article: Preventive medicine

Many diseases and disorders can be prevented through a variety of means. These include sanitation, proper nutrition, adequate exercise, vaccinations and other self-care andpublic health measures.

Treatments[edit]

Main article: 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 medications, surgery, medical devices, and self-care. Treatments may be provided by an organized health care system, or informally, by the patient or family members.

Preventive healthcare 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. Cures 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.[21]

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

Epidemiology[edit]

Main article: 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 factors 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). Epidemiology can help identify causes as well as guide prevention efforts.

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-on definition, different researchers may report different numbers of cases and characteristics of the disease.[22]

Some morbidity databases are compiled with data supplied by states and territories health authorities, at national level (National hospital morbidity database (NHMD), for example[23][24]), or at European scale (European Hospital Morbidity Database or HMDB[25]) but not yet at world scale.

Burdens of disease[edit]

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.[26]

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, has 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.[26] In the developed world, heart disease and stroke cause the most loss of life, but neuropsychiatric conditions like major depressive disorder cause the most years lost to being sick.

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