disease

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disease,

impairment of the normal state or functioning of the body as a whole or of any of its parts. Some diseases are acute, producing severe symptoms that terminate after a short time, e.g., pneumonia; others are chronic disorders, e.g., arthritis, that last a long time; and still others return periodically and are termed recurrent, e.g., malaria. One of the most common bases for classifying disease is according to cause. External factors that produce disease are infectious agents, including both microscopic organisms (bacteriabacteria
[pl. of bacterium], microscopic unicellular prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles. Once considered a part of the plant kingdom, bacteria were eventually placed in a separate kingdom, Monera.
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, virusesvirus,
parasite with a noncellular structure composed mainly of nucleic acid within a protein coat. Most viruses are too small (100–2,000 Angstrom units) to be seen with the light microscope and thus must be studied by electron microscopes.
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, and protozoansprotozoan
, informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues.
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) and macroscopic ones (fungiFungi
, kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes (see saprophyte).
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 and various parasitic wormsworm,
common name for various unrelated invertebrate animals with soft, often long and slender bodies. Members of the phylum Platyhelminthes, or the flatworms, are the most primitive; they are generally small and flat-bodied and include the free-living planarians (of the class
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). Only infectious diseases can be transmitted—by humans, certain animals and insects, and infected objects and substances (see communicable diseasescommunicable diseases,
illnesses caused by microorganisms and transmitted from an infected person or animal to another person or animal. Some diseases are passed on by direct or indirect contact with infected persons or with their excretions.
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). Other external agents that can cause disease are chemical and physical agents (drugs, poisons, radiation), which can be encountered in specific work situations, deficiency of nutrients in the environment, and physical injury. Diseases that arise from internal (endogenous) causes include hereditary abnormalities (disorders inherited from one or both parents), congenital diseases (disturbances in the development of a normal embryo), allergies (hypersensitive reactions to substances in the environment), endocrine disorders (generally either overfunctioning or underfunctioning of an endocrine gland), circulatory disorders (diseases of the heart and blood vessels), and neoplasms, or tumors (masses of abnormally proliferating cells). Degenerative diseases occur as a result of the natural aging of the body tissues. Finally, a wide range of diseases are attributed to, or at least influenced by, emotional disturbances. Psychoses and neuroses result in disturbed behavior; the so-called psychosomatic diseases (certain kinds of colitis, many forms of headaches) are thought to be brought about by emotional stress. Most diseases occur as a result of a combination of both internal and external conditions, i.e., an interaction between the body and the environment. Thus a person may be hereditarily predisposed to tuberculosis, although the tubercule bacillus (the infectious agent) must be present for the disease to occur. In ancient times disease was ascribed to supernatural, spiritual, and humoral factors. The discovery by Louis Pasteur and others of the role played by microorganisms in infection and the study of cellular pathology by Rudolf Virchow in the 19th cent. were of the utmost importance in establishing the true nature of disease.

Disease

 

a process arising as a result of an (extremely) injurious external or internal stimulus acting on the body, and characterized by lowered resistance to the environment with simultaneous mobilization of the body’s defenses.

Disease is manifested by disruption of the equilibrium between the body and its surrounding environment. This disruption is revealed by the occurrence of side (inadequate) reactions and, in man, by a decrease in work capacity for the duration of the disease.

The general concepts of disease changed in the course of the history of medicine. Hippocrates thought disease was caused by an incorrect mixing of the four main fluids of the body: blood, mucus, yellow bile, and black bile (venous blood). About the same time the idea arose from the atomistic teaching of Democrites that disease results from a change in the shape of atoms and their incorrect arrangement. At the beginning of the Christian Era and especially in the Middle Ages, idealistic views were advanced to account for disease. According to these views, the soul or a special kind of vital force (arche) was responsible for the struggle of the body against the changes caused by disease. Avicenna (ibn Sina) proposed materialistic views of disease in the Middle Ages (for example, the origin of disease under the influence of invisible beings and the role of the constitution of the body).

From the 17th through the 19th century, important contributions to the theory of disease were made by G. B. Mor-gagni (the idea that disease is caused by anatomical changes), M. F. X. Bichat (description of the pathologicoanatomical picture of several diseases), R. Virchow (theory of cellular pathology), C. Bernard (disease as a disruption of the body’s physiological equilibrium with the environment), and others. S. P. Botkin, V. V. Pashutin, I. P. Pavlov, and A. A. Ostroumov related disease to impairment of the conditions of man’s existence and elaborated on the theory of nervism.

Despite the abundance of works on disease, the concept has still not been precisely determined. Some investigators deny that disease is qualitatively different from health. A. A. Bogomolets, for example, believed that disease does not create anything essentially new in the body. Others include only biological phenomena in the concept of disease. According to P. D. Gorizontov, disease is a complex general reaction to disruption of the relations between the organism and the environment. Disease results in the development of pathological processes reflecting local manifestations of the organism’s systemic reaction. I. V. Davydovskii maintains that there are no fundamental differences between physiology and pathology. Pathological processes and disease, in his opinion, are merely characteristics of the adaptive processes associated with subjective suffering. According to H. Selye’s concept of the general adaptation syndrome, disease is stress resulting from an extreme stimulus acting on the body.

The causes of disease are varied, but they can all be reduced to groups of mechanical, physical, chemical, biological, and, for man, also psychogenic factors. Inadequacy (extremeness or unusualness) in any of these factors induces disease. Inadequacy may be quantitative (the amount of the stimulus is excessive for the body), qualitative (the body is exposed to a factor for which it has not developed protective or adaptive mechanisms), temporary (a quantitatively and qualitatively adequate stimulus acting for a long time or at intervals or in rhythms unusual for the body), or dependent on the individual properties of the particular organism (that is, determined by the individual reactivity of the particular organism in the form of increased sensitivity). The social inequality and national oppression found under capitalism cause a number of diseases and even lead to the extinction of entire peoples—for example, native Australians, bush-men, and American Indians.

Modern thought characterizes disease by the following main features:

(1) The development of disease is greatly influenced by the external environment and, in the case of man, primarily by the social environment. Changes in the internal properties of an organism, caused by environmental factors and firmly fixed (including those fixed by hereditary mechanisms), may themselves eventually play a leading role in the development of disease.

(2) Besides the etiological factor (that is, the cause) and external conditions, the body’s protective and adaptive mechanisms play an important part in the development of disease, which is largely dependent on the efficiency of these mechanisms and the extent and rate at which they become involved in the pathological process. In man, the development and course of disease is greatly affected by the psychogenic factor.

(3) Disease is an ailment of the whole organism. There are no completely isolated diseases of organs and tissues—that is, local diseases. Any disease more or less affects the entire body, but this does not preclude the principal affection of a particular organ or part of the body.

The following periods of a disease are distinguished: the latency period (the incubation period in the case of an infection), the time—which may last from a few seconds (in poisonings caused by a powerful poison) to dozens of years (in leprosy)—between the initial action of the pathogenic agent and the appearance of the first symptoms; the prodromal period, marking the appearance of the first symptoms, which may be vague and nonspecific (elevated temperature, grogginess, and general malaise) or sometimes typical of a particular disease (Filatov-Koplik spots in measles); the period of full development, ranging from several days to dozens of years (tuberculosis, syphilis, and leprosy); and the period of culmination (recovery, convalescence), which may occur rapidly, as in a crisis, or by lysis.

Diseases may be acute or chronic, depending on the duration of their course and the rapidity of intensification and disappearance of the symptoms. The appearance of additional changes that are unrelated to the direct cause of a disease, alongside its principal manifestations, is called a complication. It may arise at the height of a disease or after the principal manifestations have disappeared. Complications are an aggravating factor, and they sometimes lead to an unfavorable outcome. A disease may end in complete recovery, recovery with residual phenomena, stable changes in organs, the occasional development of new manifestations of the disease in the form of long-range sequelae, and death. Death as the culmination of a disease may occur suddenly, after a brief death struggle, or gradually, after a more or less prolonged agonal state.

Human diseases are classified according to the nature of the course (acute or chronic), the level at which specific pathological changes occur (molecules, chromosomes, cells, tissues, organs, or entire organisms), the etiological factor (mechanical, physical, chemical, biological, or psychogenic), the method of treatment (medication, surgery, and others), age- or sex-related differences (gynecologic, pediatric), and so on. The nosological principle—that is, the classification of diseases based on a grouping by related symptoms—is the most widely used. It is necessary to note that none of the existing classifications is completely satisfactory. According to the nosological principle, pneumonia, for example, may be classified as a respiratory disease, an infection, and an allergy. Therefore, it is a major task of theoretical and practical medicine to establish a modern classification of diseases.

REFERENCES

Gorizontov, P. D. Voprosy patologicheskoi fiziologii ν trudakh I. P. Pavlova. Moscow, 1952.
Davydovskii, I. V. Problemy prichinnosli ν meditsine. Moscow, 1962.
Petrov, I. R., and V. B, Lemus. “Obshchee uchenie o bolezni.” In Mnogotomnoe rukovodstvo po patologicheskoi fiziologii, vol. 1. Moscow, 1966.

V. A. FROLOV

disease

[di′zēz]
(medicine)
An alteration of the dynamic interaction between an individual and his or her environment which is sufficient to be deleterious to the well-being of the individual and produces signs and symptoms.

Disease

AIDS
mysterious new disease, incurable and usually fatal. [U.S. Hist.: WB, A:153]
Black Death
killed at least one third of Europe’s population (1348–1349). [Eur. Hist.: Bishop, 379–382]
bubonic plague
ravages Oran, Algeria, where Dr. Rieux perseveres in his humanitarian endeavors. [Fr. Lit.: The Plague]
Cancer Ward, The
novel set in cancer ward of a Russian hospital. [Russ. Lit.: The Cancer Ward in Weiss, 64]
Decameron, The
tales told by young people taking refuge from the black death ravaging Florence. [Ital. Lit.: Magill II, 231]
Fiacre, St.
intercession sought by sick. [Christian Hagiog.: Attwater, 130]
influenza epidemic
caused 500,000 deaths in U.S. alone (1918–1919). [Am. Hist.: Van Doren, 403]
Joram
suffered for abandoning God’s way. [O.T.: II Chronicles 21:15, 19]
Journal of the Plague Year
Defoe’s famous account of bubonic plague in England in 1665. [Br. Lit.: Benét, 529]
Lazarus
leper brought back to life by Christ. [N.T.: John 11:1–44]
Legionnaires’ disease
28 American Legion conventioneers die of flu-like disease in Philadelphia (1976). [Am. Hist.: Facts (1976), 573, 656]
Molokai
Hawaiian island; site of government leper colony. [Am. Hist.: NCE, 1807]
Naaman
leprous Syrian commander healed by Elisha. [O.T.: II Kings 5]
red death, the
pestilence, embodied in a masque, fatally penetrates Prince Prospero’s abbey. [Am. Lit.: Poe The Masque of the Red Death]
Rock, St.
legendary healer of plague victims. [Christian Hagiog.: Attwater, 299]
Sennacherib, army of
besieging Jerusalem, Assyrian force must withdraw after an outbreak of plague. [O. T.: II Kings 19:35; Br. Lit.: Byron The Destruction of Sennacherib in Benét, 266]
seven plagues, the
visited upon the earth to signify God’s wrath. [N.T.: Revelation]
St. Anthony’s Fire
horrific 11th-century plague. [Eur. Hist.: Brewer Note-Book, 34]
Syphilis
Fracastoro’s epic concerning Syphilis, mythical first victim. [Ital. Lit.: RHD, 1443; Plumb, 342]
ten plagues, the
inflicted upon Egypt when Pharaoh refuses to let the Israelites emigrate. [O.T.: Exodus 7-12]
Typhoid Mary
(Mary Mallon, 1870–1938) unwitting carrier of typhus; suffered 23-year quarantine. [Am. Hist.: Van Doren, 354]

disease

any impairment of normal physiological function affecting all or part of an organism, esp a specific pathological change caused by infection, stress, etc., producing characteristic symptoms; illness or sickness in general

Disease

(dreams)
The word disease literally means out of ease. Before you begin to interpret this dream on a psychological or metaphysical level, first check your health. The dream could refer to physical or emotional health.
References in periodicals archive ?
Early transmission dynamics of Ebola virus disease (EVD), West Africa, March to August 2014.
citizens travelling to Ebola-affected countries to purchase travel insurance that includes medical evacuation for Ebola Virus Disease (EVD).
Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.
In view of the reports of outbreak of the Ebola Virus Disease in 4 countries of West Africa, namely, Guinea, Liberia, Sierra Leone and Nigeria, it is recommended that non-essential travel to these countries be deferred till such time that the Ebola Virus Disease outbreak situation is brought under control," he said.
The WHO is convening an Emergency Committee on Ebola Virus Disease (EVD) under the IHR 2005 today and tomorrow.
They were working on health system strengthening long before Ebola arrived, and rapidly scaled up their efforts, including the hasty construction of an 18-bed Ebola holding unit (EHU) when the first Ebola virus disease (EVD) cases arrived in the city in May 2014.
This project aims to support the United Nations Country Team in Ghana to accelerate and strengthen government preparedness for early detection and containment of Ebola Virus Disease and prevent further spreading of the disease.
On July 29, Corgenix will present two posters during the Infectious Disease session: poster B-074 " Analytical validation of the ReEBOV Antigen Rapid Test Kit for the point of care detection of Ebola Virus Disease ;" and poster B-072 " Preliminary validation of saliva samples as clinical matrix on the ReEBOV Antigen Rapid Test Kit for the point of care detection of Ebola Virus Disease.
Mohamed Ibn Chambas, who is also the Head of the United Nations Office for West Africa (UNOWA), also warned about "continuing risks of instability in several West African nations, in the lead up to their presidential elections later in the year" as well as trans-national organized crime and the Ebola Virus Disease which "still remain a matter of serious concern in spite of continuing national, regional and international efforts to curb these threats.
The World Health Organization describes Ebola virus disease (formerly known as Ebola hemorrhagic fever) as "a severe, often fatal illness, with a case fatality rate of up to 90%".
The current Ebola virus disease (EVD) outbreak has been in progress for more than a year in Western Africa, and unfortunately has spread across international borders.
The Ebola virus disease, which was initially reported in Guinea in March, has spread to neighboring countries, with a total of some 16,000 cases and 5,700 deaths reported in the four countries, according to the World Health Organization (WHO).