Disease

A disease is an abnormal condition or impairment of the body of an organism, including any of its organs, systems, or parts, and that has a specific cause and characteristic signs or symptoms. Diseases cause discomfort, dysfunction, or distress to the organism afflicted or those in contact with the organism. Disease can also refer to an abnormal condition of the mind. Disease may be due to such factors as genetic defect, infection, diet, physical or mental stress, the environment, or a combination of these factors.

Sometimes the term disease is used broadly to include injuries, disabilities, syndromes, symptoms, infections, deviant behaviors, and atypical variations of structure and function, while in other contexts these may be considered distinguishable categories.

Prevention of disease and promotion of health and wellness are generally tied to issue of personal responsibility. Among factors important for prevention of disease are good nutrition, exercise, stress management, a healthy environment, wise use of medical resources, good human relationships, and a positive outlook on life. Spiritual health is also considered important in the overall promotion of good health. (See Principles of disease prevention and treatment.)

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. The study of diseases affecting domestic animals, wildlife, and exotic and production 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.

Various healing arts exist outside of "conventional medicine," many of which are designed to treat the whole person—the physical, mental, emotional, and spiritual aspects of health. Naturopathy, chiropractic, ayurveda, homeopathy, acupuncture, hypnosis, and herbal remedies are among techniques used in disciplines variously labeled as alternative medicine, holistic medicine, and natural medicine.

Illness can be defined as a state of poor health, with health defined by the World Health Organization as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity" (WHO, 1946). What can cause and continue this impairment of physical, mental, or social well-being includes but is not limited to disease.

The term disease is often used metaphorically for disordered, dysfunctional, or distressing conditions of other things, as in disease of society.

Syndromes, illness, symptoms, and signs

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.

Symptom

The term symptom (from the Greek syn = con/plus and pipto = fall, together meaning co-exist) has two similar meanings in the context of physical and mental health:

Strictly, a symptom is a sensation or change in health function experienced by a patient. Thus, symptoms may be loosely classified as strong, mild, or weak. In this, medically correct sense of the word, it is a subjective report, as opposed to a sign, which is objective evidence of the presence of a disease or disorder. Examples of symptoms are fatigue/tiredness, pain, or nausea. The symptom that leads to a diagnosis is called a cardinal symptom. In contrast, elevated blood pressure, or abnormal appearance of the retina, would be a medical sign indicating the nature of the disease.

A symptom may loosely be said to be a physical condition that shows that one has a particular illness or disorder (see e.g. Longman, 1995). An example of a symptom in this sense of the word would be a rash. However, correctly speaking, this is known as a sign, as would any indication detectable by a person other than the sufferer in the absence of verbal information from the patient.

Some symptoms (e.g. nausea) occur in a wide range of disease processes, whereas other symptoms are fairly specific for a narrow range of illnesses: for example, a sudden loss of sight in one eye has only a very limited number of possible causes.

Some symptoms can be misleading to the patient or the medical practitioner caring for them. For example, inflammation of the gallbladder quite often gives rise to pain in the right shoulder, which might (quite reasonably) lead the patient to attribute the pain to a non-abdominal cause such as muscle strain, rather than the real cause.

A symptom can more simply be defined as any feature that is noticed by the patient. A sign is noticed by the doctor or others. It is not necessarilly the nature of the sign or symptom that defines it, but who observes it. Clearly then, the same feature may be noticed by both doctor and patient, and so is at once both a sign and a symptom. The distinction is as simple as this, and therefore it may be nonsensical to argue whether a particular feature is a sign or a symptom. It may be one, the other, or both, depending on the observer(s). Some features, such as pain, can only be symptoms. A doctor can not feel a patient's pain (unless he is the patient!). Others can only be signs, such as a blood cell count measured by a doctor in his/her laboratory.

Transmission of disease

Some diseases, such as influenza, are contagious or infectious, and can be transmitted by any of a variety of mechanisms, including coughs and sneezes, sexual transmission, by bites of insects or other carriers of the disease, from contaminated water or food, and so forth.

Other diseases, such as cancer and heart disease, are not considered to be due to infection, although microorganisms may play a role.

Social significance of disease

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 "shell shock"; 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.

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.

Principles of disease prevention and treatment

Disease prevention is tied to personal responsibility. Among the factors that have been identified in the health promotion and wellness movements are good nutrition, exercise, stress management, wise use of medical resources, healthy environments, good human relationships, and a positive outlook on life.

A Harvard University publication on nutrition references that healthy eating can prevent 25% of all cancers and combined with exercise and being a nonsmoker can prevent up to 90% of adult onset diabetes.

Exercise has been shown to reduce risks for diseases such as heart disease, high blood pressure, diabetes, obesity, and colon cancer. In addition, exercise has been shown to also reduce risks for some mental diseases, such as depression.

Good stress management can also reduce the risk of and/or prevent disease. Stress can be a contributing or even primary factor to a number of pathologies or combination of pathologies including cardiovascular disease, mental diseases, internal organ diseases, or musculoskeletal diseases.

Wise use of medical resources includes having appropriate age related checkups to detect or catch diseases early on so they can be treated effectively. Some of the common preventive checkups include: screenings for blood pressure, cholesterol/HDL ratios, breast exams for women, and so forth. Taking vaccines is another medical resource, such as taking a vaccine for malaria before traveling to a region where malarial disease is prevelant.

Living in a healthy environment is becoming increasingly important to preventing disease. Access to clean water and sanitation, freedom from toxic chemical exposure, clean air, and so forth can help reduce and prevent disease.

Having satisfying human relationships and a positive outlook on life have been found to be a factor in the reduction and/or prevention of disease. In one study of 40,000 people performed by the U.S. Department of Health and Human Services, it was found that satisfying human relationships and job satisfaction were better predictors (inverse correlation) of heart disease than all other factors.

In general, self-responsibility for one’s health is a critical way to prevent disease. The person who takes responsibility for not smoking reduces risks for several diseases such as heart disease, stroke, lung cancer, and throat cancer, to name a few. In the same, way responsible alcohol consumption can reduce the risks for cirrhosis of the liver, alcoholism, and other mental diseases. In the same manner, taking responsibility to avoid addicting drugs can prevent disease. A person taking measures for responsible sexual behavior can also help prevent or reduce risks for several diseases, including HIV-AIDS. Using a mosquito proof net and using insect repellent while traveling in an region with insect-borne diseases can reduce such incidents, and making sure needles are sterilized can prevent infection.

Many individuals with a religious orientation emphasize the importance of spiritual health in the promotion of health. Human beings are not only physical beings, but also spiritual and social beings. Religions recognize various spiritual laws that are important to one's spiritual health, such as to love, to give, and to live for the sake of others. When one is self-centered, one violates such universal principles, leading the body to be more apt to be susceptible to disease. Following such spiritual principles is also fundamental to having good human relationships and a positive attitude in life.

Ultimately, all of the aforementioned issues—human responsibility, spiritual health, stress management, and so forth—relate to the religious issue of mind-body unity. Individuals generally know what is the right course of action—to exercise, to pass up on that donut or soft drink, to do a good deed for someone else, to not be overly concerned with oneself, and so forth. The issue really becomes one of actually doing those things, which may not be as pleasurable to the body in the short run. Thus, they are considered to be issues of mind-body unity: having the body do what the mind knows is the right course of action. That is, the mind is fundamental to good health, and good mind-body unity, centered on universal principles, will help promote good health.

Symptoms (headache, fever, high blood pressure, etc.) serve as warning signs of the deeper problem. In some cases, eliminating the symptoms—for example, a fever in a baby, sneezing caused by allergies;mdash;may be the only practical course available at the present time. However, generally the best course of action is not to simply eliminate or cover up the symptoms and then ignore the problem, but to treat the underlying causes and help the body improve its own health and ability to manage such stresses, now and in the future. The long-term solution may require making a lifestyle or environmental change to help in preventing disease.

Numerous healing methodologies are available. The Western method of taking drugs and employing surgery has been effective in many cases. However, many healing arts do exist that are designed to treat the whole person and that address more than in conventional medicine. Alternative medicine includes naturopathy, chiropractic, ayurveda, homeopathy, and acupuncture. Holistic medicine strives to pay attention to not just the physical, but also the mental, emotional ,and spiritual aspects of health, using such techniques as hypnosis and visualization. Natural medicine involves herbal remedies, diet, and water therapies. In addition to these alternative methods of healing, there is also the method of faith healing, that addresses the issue of a spiritual cause to disease.

List of common diseases

This is a list of common, well-known, or infamous diseases. This is neither complete nor authoritative. This is not intended to be a list of rare diseases, nor is it a list of mental disorders. This list includes both common names and technical names for diseases. A number of rare diseases may be present in this list.

List of diseases (in alphabetical order):

Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Achondroplasia
Acne
Adenoma]]*
Ageing
AIDS
Albinism
Alcoholic hepatitis
Alopecia
Alzheimer's disease
Amblyopia
Amoebiasis or Amebiasis
Anemia
Aneurysm
Anosmia
Anotia
Anthrax
Appendicitis
Apraxia
Argyria
Arteritis
Arthritis
Aseptic meningitis
Asthenia
Asthma
Atherosclerosis
Athetosis
Atrophy
Autism

B

Bacterial meningitis
Beriberi
Bipolar disorder
Botulism
Brucellosis
Bubonic plague

C

Calculi
Campylobacter infection
Cancer
Candidiasis
Cardiac arrest
Chagas disease
Chalazion
Chancroid
Cherubism
Chickenpox
Chlamydia
Chlamydia trachomatis
Cholera
Chordoma
Chorea
Chronic fatigue syndrome
Cleft lip
Coccidioidomycosis
Colitis
Color blindness
Common cold
Condyloma
Congestive heart disease
Coronary heart disease
Cowpox
Cretinism
Cystic Fibrosis

D

Diabetes mellitus
Diphtheria

E

Ebola
Encephalitis

F

Foodborne illness

G

Gonorrhoea
Glandular fever

H

Huntington's disease
Hypertension

I

Ichthyosis
Influenza
Interstitial cystitis
Iritis
Iron-deficiency anemia
Irritable bowel syndrome
Jaundice / Hepatitis

J

Jaundice

K

Keloids
Keratosis pilaris(
Kuru
Kwashiorkor

L

Lazy eye
Lead poisoning
Legionellosis
Leishmaniasis
Leprosy
Leptospirosis
Listeriosis
Leukemia
Loiasis
Lupus erythematosus
Lyme disease
Lymphogranuloma venereum
Lymphoma

M

Malaria
Marburg fever
Measles
Melioidosis
Ménière's disease
Meningitis
Migraine
Multiple myeloma
Multiple Sclerosis
Mumps
Muscular dystrophy
Myasthenia gravis
Myelitis
Myoclonus
Myopathy
Myopia
Myxedema
Meninggococemia

N

Neoplasm
Non-gonococcal urethritis

O

Obsessive-compulsive disorder
Obesity
Osteoarthritis

P

Paratyphoid fever
Parkinson's disease
Pelvic inflammatory disease
Peritonitis
Periodontal disease
Pertussis
Phenylketonuria
Pityriasis rosea
Plague (bubonic, septicemic, pneumonic, and pharyngeal)
Pneumonia
Polio or Poliomyelitis
Porphyria
Progeria
Prostatitis
Psittacosis
Psoriasis
Pubic lice

Q

Q fever

R

Rabies
Raynaud's disease
Repetitive strain injury (RSI)
Rheumatic fever
Rheumatoid arthritis
Rickets
Rift Valley fever
Rocky Mountain spotted fever
Rubella
Rheumatic heart disease

S

Salmonellosis
Scabies
Scarlet fever
Sciatica
Schizophrenia
Scleroderma
Scrapie
Scurvy
Sepsis
SARS
Shigellosis
Shingles
Shock
Sickle-cell disease
Siderosis
Silicosis
Smallpox
Stevens-Johnson syndrome
Strabismus
Strep throat
Streptococcal infection
Synovitis
Syphilis

T

Taeniasis
Tay-Sachs disease
Teratoma
Tetanus
Thalassaemia
Thrush
Thymoma
Tinnitus
Toxic shock syndrome
Trichinosis
Trichomoniasis
Trisomy
Tuberculosis
Tularemia
Tungiasis
Typhoid or Typhoid fever
Typhus

U

Ulcerative colitis
Uremia
Urticaria
Uveitis

V

Varicella
Vasovagal syncope
Vitiligo
Von Hippel-Lindau disease

W

Warkany syndrome
Warts
Whooping cough (Pertussis)

X

Y

Yellow fever
Yaws

Z

References
ISBN links support NWE through referral fees

Harvard Medical School. 2006. Healthy Eating: A guide to the new nutrition. A Special Report of the Harvard Medical School. http://www.health.harvard.edu/special_health_reports/Healthy_Eating.htm (accessed July 2, 2006).
World Health Organization (WHO). 1946. Constitution of the World Health Organization. http://w3.whosea.org/aboutsearo/pdf/const.pdf.

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

History of "Disease"

Note: Some restrictions may apply to use of individual images which are separately licensed.