AETIOLOGY

From Big Medical Encyclopedia

AETIOLOGY (Greek aitia the reason + logos the doctrine) — the doctrine about the reasons and conditions of developing of diseases; in narrower sense the term «aetiology» designate an origin of a disease or morbid condition.

The question of why the person got sick, was in medicine one of main since the most ancient times, it remains to that and in a crust, time. Its statement and the decision during various historical periods were in direct dependence on the level of development of science, philosophical and religious views, the dominating sociological theories. It is as accurate anywhere as in the doctrine about the reasons of diseases of the person, change of idealistic views on materialistic is not traced, connected with achievements of biology, physics, chemistry. However I. P. Pavlov's words that «an etiology — the weakest department of medicine» still considerably are valid.

Even in the ancient time, when mystical ideas of the non-material force which is installed in the person and causing a disease and death were widespread there were attempts of a materialistic explanation of the reasons of diseases, in particular in Hippocrates's doctrine the role of the wrong mixing of various liquids of an organism (dyscrasia) was noted. In the past there were doctrines of mekhanitsist, atomist, gumo-ralist, etc., however deprived of strict scientific justification, they could not shake seriously idealistic views on essence and the reasons of diseases, especially in the conditions of the influence of church dominating those years.

Scientific development E., in essence, began in 19 century. The significant role was played at the same time the cellular theory (see) and the cellular pathology created by R. Virkhov on its basis (see). It was shown that diseases of the person have quite certain structural basis consisting in changes of cells, and different diseases are characterized by damage of bodies, fabrics and cells, specific to each of them. Though cellular pathology had also not a direct bearing on clarification of origins of diseases and focused attention only on direct action of pathogenic factors to cells, its value for development E. is that accurate justification of the material nature of the functional disturbances characteristic of this or that disease, already in itself sent a thought of researchers to search for the specific material reasons of these disturbances.

The major stage in the history of development E. opening in the second half of 19 century of microorganisms — activators inf was. diseases of the person. Earlier assumed their existence, but without microscope visually could not observe and were limited to uncertain statements about «miasmata», «the infectious beginning» etc. Value of achievements of microbiology consisted in what as the reasons of diseases of the person instead of mythical non-material force specific objects of the world around began to consider, and it, in turn, struck blow to century idealistic ideas of the reasons and entities patol. processes, approving the materialistic principles of a determinism (see). Further idea of the reasons of diseases continuously extended due to inclusion in their number all of new factors of external and internal environment. In a crust, time as such factors allocate physical (injuries, thermal influences, ionizing radiation, atmospheric influences, etc.), chemical (to - you, alkalis, various poisons etc.), biological (pathogenic microbes, viruses, various endogenous substances), and also social.

Besides, the disease can be caused by deficit in the environment or in an organism of substances (factors) necessary for life activity (starvation, hypovitaminoses, a mountain disease, immuno scarce

states, etc.) *

From the moment of opening of microorganisms and prior to the beginning of 20 century etiol. attached to factors almost absolute value in developing of diseases and connected health or a disease of the person only with absence or existence of these factors. Further, however, became more and more obvious that not always one influence of a pathogenic factor caused developing of a disease; an important role is played at the same time also by a condition of an organism. So, at the beginning of 20 century the doctrine about reactivity of an organism (see) claiming that different organisms react to action of the same environmental factor unequally — one violently others was created it is very weak or absolutely imperceptible. It was established that specific anatomo-physio-logical features of an organism, its constitution (see), age, sex can also have significant effect on development of diseases, and, nek-ry of these features others contribute to one diseases — to others. There was obvious a role of heredity (see) in development of various infectious and noninfectious diseases. The great value during the developing of diseases of negative influence on an organism of such socially caused factors was confirmed as defective food, wearisome work, insanitary living conditions, unemployment, alcoholism (see), drug addiction (see), and others, playing an important role in predisposition of an organism to many diseases and causing heavier, than usually, their current and an outcome. Significant effect on growth of incidence render environmental pollution (see Environmental control), various professional to harm (see). As pathogenic factors it is necessary to consider also specific local conditions, to-rye are object of studying of geographical pathology (see). Thus, in E. diseases the great value belongs to the social factors caused by character of an economic and political system of the state: if in the capitalist countries these influences accept more and more menacing sizes, then in the countries of socialism against them more and more broad and effective preventive actions are carried out in the state scale (see Prevention primary).

In a crust, time in connection with rapid development of genetics, immunology, molecular pathology and other scientific disciplines the in-depth study of the thinnest mechanisms of cell activity at the known derivation of attention of researchers from further studying of the general regulatory systems of an organism doing to its whole is characteristic: development of private pathology of a cell advances progress of the general pathology of the person. It first of all concerns less intensive, than before, developments of problems of a nervosism (see), roles of a nervous system (see) as the main integrating system of an organism defining interaction of all its parts among themselves and an equilibration with the environment. Meanwhile the wedge, experience prompts that «a nervous factor» — hron. the overstrain of a nervous system, negative emotions, the conflicts in the subconscious sphere, i.e. all that it is accepted to carry to so-called psychosomatic frustration, and also dyskinesia, vegetodistoniya and other states quite often contribute to developing of a disease.

Thus, since the beginning of 20 century the etiology of diseases of the person developed in the following main directions: on the one hand, scientists opened the reasons of diseases of earlier unknown origin and on this basis developed methods of their effective etiological treatment, and with another — revealed the new conditions promoting or, on the contrary, interfering their development. At the same time philosophical discussions on questions E. were developed not only in the plane of fight of idealism against materialism, but also as if in materialism between supporters of the simplified mechanistic interpretation of interaction of an organism with the environment and those who stood on positions of dialectic understanding of this interaction. Among supporters of the simplified mechanistic interpretation of problems E. also there were disagreements. One researchers claimed that in a course of a disease its main reason has the defining value, and all other factors at the same time do not play an essential role. This referral was got by the name of a monokauzalizm (see). Supporters of the opposite point of view considered that everything is defined only by set of conditions in this specific situation, all these conditions are equal (are equipotential) and it is impossible to distinguish it from them, on a cut it would be possible to point as to the only etiology. This direction was called a konditsionalizm (see); M. Fervorn was his ancestor. Both of these points of view are unilateral: the monokauzalizm does not consider in the presence of the main reason for a disease undoubtedly importance and various conditions, in to-rykh there is a disease, and the konditsiona-lizm levels so undoubted value of the specific reason of this or that disease, completely equating it to other conditions and ignoring the principle of causality. The reasons and conditions of developing of diseases need to be considered in their dialectic unity, i.e. in continuous and close interaction of that and others at preservation of specific value of each of them (see Causality).

The etiology should be considered a factor, without to-rogo it cannot arise under no circumstances. So, for lack of microorganisms cannot develop corresponding inf. diseases, were not as if heavy environmental conditions and in what features reactivity of an organism would not differ. Injuries are also caused by action of a specific disturbing factor. The main reason for a disease can work on an organism far back in the past, but the changes once caused by it in biol. to system pass from father to son, and each new individual is sick, in essence, already regardless of this reason. It takes place at hereditary diseases (see) when as the main thing etiol. a factor continuously functioning mutant gene (e.g. acts, at hemophilia). In some cases the same pathological process (see) arises under the influence of environmental factors various in character. In this case speak about a poly-etiologichnosti of this disease. So, it is established that ionizing radiation, effect of chemical carcinogens, viruses, disturbance of hormonal balance of an organism, etc. can be the cause of malignant growth (see Tumours). At the same time it is necessary to consider that all these various pathogenic factors influence the genetic device of a cell, various disturbances to-rogo are a source of their uncontrollable proliferation. The different reasons can sometimes cause the same kliniko-anatomic syndrome, affecting different releasers of this syndrome, napr, arterial hypertension (see arterial hypertension) arises at various forms of damage of kidneys, tumoral processes in adrenal glands. However in most cases not the valid variety of the reasons causing this disease, and her Em's ignorance substituted by various hypotheses, assumptions, reasonings on so-called risk factors, etc. is behind the term «polietiologich-nost». Thus quite often explain in a crust, time of the reason of atherosclerosis (see), a peptic ulcer of a stomach (see. Peptic ulcer), cholecystitis (see) etc. In similar cases it is necessary to treat the term «polietiologich-nost» critically, considering that it reflects only the current state of a question and demands further researches for exact identification of the valid reasons of this disease.

Often, especially in connection with lengthening of average life expectancy, people has not one, but several diseases, i.e. simultaneous action of a row etiol takes place. factors, each of to-rykh causes development defined nozol. forms. Performing effective treatment in these conditions requires accurate identification all acting in this case etiol. factors and establishment of specific weight and the importance of each of them in the general a wedge, a picture. In this regard allocate the «main» disease «competing» with it, «accompanying», «background», etc.

The central place in the modern doctrine about the reasons of diseases of the person holds position that action of any of the reasons is implemented not directly, and always indirectly through interaction with fiziol. systems of an organism. From an organism this interaction is in that at changes of living conditions, at action even of the strongest pathogenic irritants causing acute and chronic diseases to keep constancy of the internal environment, or a homeostasis (see) and by that as K. Bernard told, to continue «free, independent life». On expression And. V. Davydovsky, «environmental factors constantly „test” adaptive mechanisms of the person for „durability”, mobility of the structures and physiological correlations which are the cornerstone of health». Adaptation of an organism to continuous influences of the environment (see Adaptation) is provided by means of adaptive reactions, among to-rykh allocate group compensatory, the expressed disturbances of structure and function of bodies joining in case of. Thus, a problem of developing of this or that disease of the person (see the Disease), it E., far it is not limited to identification etiol. factor per se, and much more difficult also consists in establishment of all variety of relationship between this factor and an organism in respect of dialectic interaction external and internal. And. V. Davydovsky wrote: «The analysis of etiologiche-chesky factors at an individual disease always shall be the analysis external (ecology) and internal (immunity, age, sex, the constitution it.). Eventually internal factor (developing historically in fi l about - and ontogenesis) resolves an issue of developing of diseases». The inflammation, immune responses, fervescence at fever belong to internal factors, a hyperglobulia at a hypoxia and other reactions, to-rye are directed to recovery of the homeostasis broken as a result of action of pathogenic factors.

Neutralization of action of pathogenic environmental factors is carried out by an organism by means of system of compensatory reactions (see. Compensatory processes). This system differs in the high power and exclusive potentialitys. It can neutralize action of pathogenic factors completely. Quite often the disease is shown in very easy, quickly passing form and then speak about its abortal current. If the organism does not manage to liquidate quickly effect of pathogenic influence, then he by means of compensatory reactions can stop a long time action of this or that pathogenic factor. As a result of it the disease which is slowly progressing in the morfol. expression, clinically it is not shown, and the person remains almost healthy until there occurs failure of compensation and there will be no corresponding subjective and objective symptoms of a disease. Such sequence of the phenomena complicates early diagnosis as the first symptoms of a disease quite often appear only when the disease already far came in the development, and, the compensatory and adaptive opportunities of an organism are higher, the later there are the first wedge, symptoms of a disease — atherosclerosis, a tumor, a peptic ulcer, cirrhosis, etc.

Extreme influences of the environment, various defects of the genetic device, negative social, mental and other impacts adversely affect relationship of an organism with pathogenic factors since reduce efficiency of its compensatory and adaptive reactions.

Unlike the reasons of diseases of a condition of their emergence can be the most various, but any of them is not absolutely necessary for development of this or that disease. Play a major role in one cases of an etiology and depend on conditions a little, in to-rykh they work. It takes place at influence of the extreme factors of the environment exceeding the highest degree of body resistance (a severe injury, a burn, especially dangerous infections) though even in these cases, in particular at epidemics of the most dangerous infections, death comes not always. However much more often various conditions have significant effect on etiologies. This influence happens weakening or strengthening. Relationship between the reason and conditions of a disease can develop in such a way that the last completely neutralize its main reason: e.g., carrier tubercular paslochka in most cases for years remains almost healthy person; the powerful system of immunity destroys the tumor cells which are permanently appearing in an organism owing to defect of the genetic device; many compensated malformations for years, and quite often all life clinically are not shown. On the other hand, conditions of surrounding and internal environment can be decisive factor in a course of a disease. Quite so, owing to activation of autoinfection (see), there is pneumonia after operative measures, many viral diseases during the overcooling, aggravations of chronic pathological processes at overfatigue, disturbance of a diet, negative emotions, etc.

The reasons and conditions of development of diseases are in the most various ratios. In this regard quite often difficult happens to define what is the reason of this disease, and that the condition promoting its development. In these cases for differentiation of the reasons of the diseases and conditions promoting their emergence it is necessary to be guided on etiol. classification of diseases and the principle of a nosology (see) that is to recognize that each disease of the person is characterized by a combination, strictly specific to it, etiol. a factor, a pathogeny (see) and a kliniko-anatomic picture. Therefore the main reason for pneumonia (see) always there will be this or that species of microorganism, and overcooling, an operative measure, later to-rogo there was a pneumonia, developments of stagnation in lungs connected with heart failure and other circumstances — only various conditions and starting factors promoting activation of autoinfection. The major role in development of specific allergic reaction (see the Allergy) is played by allergen (see) while at a nonspecific hyperergy the main reason patol. process consists in disturbances of a condition of the organism, and the allergens which in the first case are an etiology act as the conditions which caused its flash. Thus, the conditions promoting developing of this or that disease can play the same essential role, as well as its reasons. It does almost important examination not only the basic etiol. a factor given nozol. forms, but also all those conditions, to-rye, interacting with this factor, promote developing of a disease or, on the contrary, interfere with its development. Only at such approach it can be reached both effective therapy of diseases of the person, and their prevention: not the reason and conditions taken separately but only the reason and conditions in their dialectic unity can be the main reference point at clarification of why and as the disease at this subject developed (see Konditsionalizm, Causality).

In theoretical and especially in the practical relation the question of the future etiol is very important. a factor after there was a disease. In one cases it, having caused patol. process, at once disappears, and the disease develops further owing to the functional and structural disturbances replacing each other by the principle of the cause and effect relations. However the important role etiol is much more often. a factor can remain throughout all disease. Concerning, e.g., infectious diseases more and more data on a long persistirovaniye in an organism of viruses of hepatitis (see a viral hepatitis), a lymphocytic choriomeningitis (see the Choriomeningitis lymphocytic), acute disseminated encephalomyelitis (see), a tick-borne encephalitis (see a tick-borne Encephalitis), and also about a number of the special viruses which for many years are present at an organism and causing development of so-called slow infections collect (see. Slow viral infections). It demonstrates that «start» patol. process the role of a virus is not limited, and throughout a disease it plays an important role in its progressing and aggravations. At bacterial infections it cases of a long persistirovaniye of mycobacteria of a leprosy confirm the facts of a long persistirovaniye of the mycobacteria of tuberculosis (see) transformed to L-forms (see L-forms of bacteria), in the centers of so-called residual tubercular changes at the people almost healthy concerning this disease, (see).

Concerning noninfectious diseases question of destiny etiol. a factor, i.e. about its disappearance and a persistirovaniye after it induced a disease, remains open as the reasons of the majority of these diseases are not found out yet. For this reason in a crust, time drastic remedies of prevention and treatment of an idiopathic hypertensia (see), atherosclerosis, a peptic ulcer, cholecystitis, chronic forms of nephrite (see), pneumonia, rheumatism are not developed (see) and other diseases, and the applied treatment mainly is directed not to an etiology, and only to its manifestations and complications. However there are sufficient bases to consider, as in these cases etiol. the factor works continuously and supports hron. disease. So, atherosclerosis is continuously progressing process not because atherosclerotic plaques, since some moment increase in itself (experimental data say that the atheromatosis is reversible) and because that factor (factors) continuously works, to-ry leads to the known disturbances of a homeostasis in the field of a metabolism in general and lipids in particular. The same fully treats also anatomic effects of atherosclerosis: the cardiosclerosis progresses not in itself but only in connection with increase of atherosclerotic narrowing of coronal arteries or with repeated myocardial infarctions. Even the large hems of a myocardium formed around foreign bodys (a bullet, a splinter) after removal of the last, i.e. after full elimination of the reason which caused patol. changes of a muscle of heart, do not increase any more and for years can keep those sizes, to-rykh they reached by the time of operation. In many cases when the etiology is known and it it is possible to eliminate completely, both «self-development» of process, and its «self-movement», «autonomy», «independence of an etiological factor» stops at once if it is not possible to make it, the disease proceeds. E.g., so-called symptomatic hypertensia are eliminated after removal of a pheochromocytoma (see Hrom-affinoma), inborn narrowing of a renal artery while an idiopathic hypertensia, the reason a cut is still unknown and progressing a cut can be slowed down only gradually, steadily develops, periodically becoming aggravated.

In a pathogeny hey that allergic diseases (see) assume an element of self-development on the basis of short circuit of a vicious circle, but concerning many of them the pathogenetic role of autoantibodies and sensibilized lymphocytes is not proved therefore it is unknown whether the disease on this vicious circle automatically progresses, i.e. in itself, or this process is continuously supported by some attending starting factors.

The role etiol is not absolutely clear. factors in further progressing and malignant new growths where, apparently, not everything is as simply as it follows from the known formula «carcinogen disappeared — cancer continues to develop», especially if it is about clinical, but not about experimental aspect of this problem, in particular not about perevivny tumors, and about developed spontaneously.

In the field of nervous and mental diseases it is quite often raised a question of independence of progressing of a disease of the reason which raised it, however idea of disappearance of the prime cause patol. process, napr, neurosis (see), in relation to mental diseases conditionally also demands the careful analysis in each case. So, it is known that the careless word of the doctor can be a source of an iatrogenic disease (see). In this case, undoubtedly, etiol. a factor is the word, a cut strongly sinks down in consciousness of the patient and becomes the permanent reason of neurosis. The etiological psychotherapy in this case is based on suggestion to the patient that it is healthy.

The opinion expressed by nek-ry researchers on what is frequent etiol. factors of a disease only start it, further completely losing the defining value, needs specification. The similar option of disease is possible, but in incomparably bigger number of cases of infectious, viral, somatic diseases, numerous chronic poisonings, hypovitaminoses and other diseases etiol. the factor can is long to persistirovat, disappear (for years), but then again to appear, causing a recurrence. Thus, change of the cause and effect relations, edges surely takes place during this or that disease, can happen as at absence etiol. the factor which started it and in the conditions of the continuing influence not only this factor, but also effects of action of the secondary, tertiary and other reasons which are consistently inducing each other in process of expansion patol accumulating on it. process. Each subsequent reason does not remove and does not deny previous, and is summed up with it, burdening disease by new complications. This circumstance is especially important poto-

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mu that it warns against frequent revaluation of a role of nonspecific factors in formation and a current patol. processes.

Idea of a so-called starting role etiol. factors of diseases of the person, to-rye further progress already regardless of these factors on the basis of own internal patterns by the principle of self-development, led to a gap between the doctrine about etiologies — an etiology — and the doctrine about mechanisms of its development — a pathogeny (see) that was shown by decrease in attention to the first and assignment by it, to a certain extent, a supporting role in expansion a wedge, pictures of a disease and especially in its progressing. Meanwhile the increasing number of the facts, testimonial collects that an etiology (in a broad sense) and a pathogeny is cost in the general course of disease, are not separate, and, on the contrary, are integrally connected and coexist throughout many and especially chronic diseases of the person, closely intertwining and causing a variety of their kliniko-anatomic manifestations. Studying of mechanisms patol. processes, fairly considered as one of the central problems of theoretical medicine, it is necessary to carry out taking into account a role etiol. the factors which are inducing, and in many cases and continuously maintaining activity of these mechanisms. Therefore, this task is not purely pathogenetic, and complex, i.e. equally and etiological. An etiology and a pathogeny — two parties of any patol. process, without to-rykh cannot exist process. M. P. Konchalovsky (1937) wrote: «Any therapy is the therapy combined. Now speak about active methods of therapy much. Meanwhile these methods cannot be called in any way active because they are not directed to an etiology or essence of a disease». Under such visual angle it is necessary to consider progressive value of works of V. D. Tsinzerlinga and And. V. Tsinzerlinga who accurately raised a question that there is no pneumonia at all, and there is pneumonia staphylococcal, pneumococcal and other types of pneumonia, i.e. again emphasized a role etiol. a factor not only in «start», but also during and outcomes of pneumonia. Careful searches of the slightest purulent zatek and their elimination at patients with a heavy septic current of a wound process reflect critical review of a view of similar a wedge, a picture as on already «samorazvivayu-ztsuyusya», become independent of primary suppurative focus. Such


approach allows to stop this «self-development» of septic process in many cases and to save the patient.

A wedge, practice shows that etiol. treatment is especially effective, providing an absolute recovery of the patient. Main progress in treatment inf. diseases are caused first of all by discovery of antibacterial agents. At the same time radical treatment and even complete elimination of many inf. diseases were reached almost only on the basis of knowledge etiol. factors and development of means of fight against them at incomplete idea of a pathogeny of these diseases irrespective of exact knowledge of mechanisms of their development. Efficiency of therapy hron. poisonings with compounds of lead (see), mercury (see), beryllium (see) and other metals, radioactive materials (see) also is in direct dependence on increase in degree of its «etiologichnost», i.e. on in what measure treatment provides neutralization and removal from an organism of the toxic agent. The proof of it is success achieved in therapy hron. intoxications in connection with opening and a wedge, use of complexons (see) — the substances allowing to strengthen sharply removal from an organism of this or that of the permanent toxic agent in it.

On the contrary, lack of accurate data on an etiology of many other diseases (atherosclerosis, idiopathic hypertensia, cholecystitis, malignant tumors, etc.) is the main reason that their treatment is limited to impact only on this or that separate link patol so far. process. It brings in one cases to elimination of the most serious anatomic consequences of process (an oncotomy, stomach ulcers, stones of a bilious channel), to others — to completion of this or that link which «dropped out» of complete system of an organism (so-called replacement hormonal therapy, transplantation), thirdly, on the contrary to weakening patholologically of the strengthened activity of one of these elements (decrease in the high ABP, hypersecretion mucous a stomach, etc.), however at all these kinds of pathogenetic therapy we are still far from that ideal of medical intervention, to-ry consists in eradication of etiologies. It does not exclude that sometimes, napr, at shock, a coma, terminal states developing during a disease and after operative measures, pathogenetic therapy in fight against these states in intensive care units takes the important place. If


the etiology is known also a role etiol. a factor remains on all its extent, etiol. therapy acts into the forefront, of course, in combination with pathogenetic. And only when etiol. the factor is only the push starting patol. process, the doctor is limited to pathogenetic and symptomatic therapy. Thus, only the harmonious combination of etiological and pathogenetic therapy will give the chance to medicine to become what it, according to I. P. Pavlov, «shall be, i.e. conscious and consequently, always and quite reasonablly acting».

See also Disease, Prevention, Prevention primary, Therapy.

Bibliogrgorizontov P. Dl

0 some methodological mistakes:

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Яндекс.Метрика