The disease is a complex dynamic process that consists of a number of periods.
Pre-illness period. The concept of pre-disease was introduced into pathophysiological science by S. M. Pavlenko in 1969. The term pre-disease is not yet precisely determined, however, it implies a state when sanogenetic mechanisms are either overstressed or weakened (as a result of exposure to adverse factors, due to the transfer of another disease, etc.). In this situation, a factor that does not cause disease in an organism with normal sanogenetic mechanisms may become inadequate for given organism and cause disease. Thus, the state of pre-illness can be interpreted as non-specific, as a background against which a pathogenic agent can more easily cause a disease than under other conditions.
Latent (incubation) period. This is the time elapsed between the moment of impact on the body of a pathogenic factor and the appearance of the first symptoms of the disease. During the latent period, the primary sanogenetic mechanisms are depleted. In case of development infectious disease this period is called the incubation period and is associated not only with an overstrain of sanogenetic mechanisms, but also with the accumulation of the pathogen.
Prodromal period (the period of precursors). At this time, the first signs of the disease are revealed, which are of a nonspecific nature: general malaise, fever, chills, headache etc. The onset of the prodromal period indicates that the primary sanogenetic mechanisms are no longer able to protect the body, and the disease develops.
The period of the disease. During this period, symptoms characteristic of this disease. There may also be complications of the disease, that is, pathological processes that are the result of not only the causative factor that caused the disease, but also adverse conditions that have arisen in the dynamics of the disease. For example, a complication peptic ulcer stomach may be gastric bleeding.
During the height of the disease, secondary sanogenetic mechanisms are included in the process, and the outcome of the disease depends on their confrontation with the mechanisms of pathogenesis.
convalescence period characterized by the predominance of sanogenetic mechanisms over pathogenetic ones, the gradual disappearance of the symptoms of the disease, the normalization of impaired functions. However, since the sanogenetic mechanisms are not yet fully restored, complications may occur at this time. Recovery can be complete if all body functions disturbed during the course of the disease are restored without exception, and incomplete when such restoration does not occur (for example, residual neurological phenomena after poliomyelitis). These residual effects can be so pronounced and harmful to the body that they themselves often lead to death.
Consideration of the periods of the disease clearly shows that the disease is a dialectical unity and confrontation between the mechanisms of pathogenesis and sanogenesis, and the predominance of one of these processes ultimately determines the outcome of the disease. Understanding the dialectic of the disease process has great importance and for medical tactics doctor.
This period is characterized by the appearance and (often) an increase in the most characteristic clinical and laboratory signs specific to a particular infectious disease. The degree of their severity is maximum in manifest forms of infection.
By assessing these signs, you can:
Make the correct diagnosis;
Assess the severity of the disease;
Assume the nearest forecast;
Prevent the development of emergency conditions.
The main forms of the infectious process can be presented in the form of the following table
Transient (asymptomatic, healthy) carriage- a single (accidental) detection in the human body of a pathogenic (or any other) microorganism in tissues that are considered sterile (for example, in the blood). The fact of transient carriage is determined in a series of sequential bacteriological tests. At the same time, currently existing methods of examination do not allow to identify clinical, pathomorphological and laboratory signs diseases.
Carrying pathogenic microorganisms possibly in the recovery phase infectious disease(convalescent carriage). It is characteristic of a number of viral and bacterial infections. Depending on the duration, convalescent carriage is divided into acute (up to 3 months after clinical recovery) and chronic (over 3 months). In these cases, carriage is asymptomatic or occasionally manifests itself at the subclinical level, but may be accompanied by the formation of functional and morphological changes in the body, the development immune reactions.
Carrying- this is a peculiar form of the infectious process, in which the macroorganism after the intervention of the pathogen is not able to completely eliminate it, and the microorganism is no longer able to maintain the activity of the infectious disease. The mechanisms of the development of carriage have not been sufficiently studied so far, methods for the effective rehabilitation of chronic carriers have not yet been developed in most cases. It is assumed that the formation of carriage is based on a change in immune responses, in which selective tolerance of immunocompetent cells to pathogen Ag and the inability of mononuclear phagocytes to complete phagocytosis are manifested.
Carrier formation can be facilitated by:
Congenital, genetically determined features of the macroorganism;
Weakening defensive reactions due to previous and concomitant diseases;
Reduced immunogenicity of the pathogen (decrease in its virulence, transformation into L-forms).
The following factors are associated with the formation of carriage:
Chronic inflammatory diseases various organs and systems;
Helminthiases;
treatment defects;
The nature of the course of an infectious disease, etc.
The duration of the carriage of various pathogenic microorganisms can vary extremely widely - from several days (transient carriage) to months and years (chronic carriage). Sometimes (for example, when typhoid fever) carriership can be maintained for life. The possibility of developing microbial carriage is characteristic of many infectious diseases.
Inapparent infection- one of the forms of the infectious process, characterized by the absence of clinical manifestations disease, but accompanied by an increase in titers of specific antibodies as a result of the development of immune reactions to the pathogen antigen.
Manifest forms of the infectious process constitute an extensive group of infectious diseases caused by exposure to the human body of various microorganisms - bacteria, viruses, protozoa and fungi. For the development of an infectious disease, it is not enough just to introduce a pathogenic pathogen into the human body. The macroorganism must be susceptible to this infection, respond to the pathogen with the development of pathophysiological, morphological, protective, adaptive and compensatory reactions that determine the clinical and other manifestations of the disease. At the same time, the micro- and macroorganism interact in certain, including socio-economic, conditions. external environment inevitably affecting the course of an infectious disease.
The nature, activity and duration of the clinical manifestations of an infectious disease, which determine the degree of its severity, can be extremely diverse.
With a typical overt infection, clinical signs are clearly expressed and common features characteristic of an infectious disease:
The sequence of changing periods;
The possibility of developing exacerbations, relapses and complications, acute, fulminant (fulminant), protracted and chronic forms;
Formation of immunity.
The severity of overt infections can be different:
Easy; - medium; - heavy.
Prions cause a special form of disease known as slow infections.
They are characterized by:
Many months or even many years of incubation period;
Slow but steadily progressive course;
A complex of peculiar lesions individual bodies and systems;
Development of oncological pathology;
Inevitable death.
Atypical overt infections may present as erased, latent and mixed infections.
The period of extinction of symptoms (early convalescence) Follows the peak period with a favorable course of an infectious disease. It is characterized by the gradual disappearance of the main symptoms. One of its first manifestations is a decrease in body temperature. It can happen quickly, over a few hours (crisis), or gradually, over several days of illness (lysis).
The period of recovery (reconvalescence) Develops after the extinction of the main clinical symptoms. Clinical recovery almost always occurs before the morphological disorders caused by the disease completely disappear.
In each case, the duration of the last two periods of an infectious disease is different, which depends on many reasons.
aggravation infectious disease is considered a re-aggravation general condition patient with an increase in characteristic clinical signs diseases after their weakening or disappearance.
If the main pathognomonic signs of the disease develop again in the patient after the complete disappearance of the clinical manifestations of the disease, they speak of her relapse.
Modern doctrine of the epidemic process
includes three sections:
1) factors epidemic process;
2) the mechanism of development of the epidemic process;
3) manifestations of the epidemic process.
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A disease is a state of the body in which normal vital activity and the ability to maintain self-regulation are disturbed, life expectancy decreases, which is caused by a limitation of functional and energy capabilities in their opposition to pathogenic causes.
The nomenclature of diseases includes a wide list of names of existing nosological forms that are used in medicine for a uniform designation pathological conditions. Up to today this list of diseases is not complete.
The specificity of any infectious disease lies in its cyclic nature. The following consecutive periods of the disease are distinguished: incubation, initial, peak of the disease and recovery. Each of them has its own characteristics.
latent stage of the disease
This stage is also called the incubation stage. This is a period of latent development that does not manifest itself clinically: from the moment when the pathogenic agent had an impact on the body, to the development of the first symptoms of the disease. A feature of this stage is an ever-increasing decrease in the body's ability to prevent pathogenic effects, adaptive mechanisms are no longer working as efficiently. During this period, there are no pronounced symptoms, but if a person performs stress tests, individual signs may appear.
The incubation period of the disease lasts from several minutes to several months, and sometimes even years. It all depends on the body's resistance to the influence of a pathogenic agent, on how much it is able to overcome the resulting violations with the help of protective devices. Only after exposure to strong poisons occurs almost instantaneous poisoning (no longer than a few minutes). If the latent period is set in time, this will greatly facilitate the prevention and control of the disease.
What other periods of illness exist?
Harbinger stage
Another name for this stage is prodromal. It is observed from the moment of the first manifestations and continues until the development of the usual clinical picture. The prodrome stage is a natural result of the insufficient effectiveness of adaptation processes, the main function of which is to normalize the homeostasis of the body at a time when the causes of the disease are acting.
At this stage, the first subjective and objective non-specific signs appear: fatigue, malaise, pain in the muscles and joints, irritability, decreased appetite, discomfort, headaches, fever, sometimes chills, etc. Let's consider the remaining periods of the disease.
Stage of severe disease
During the stage of pronounced manifestations, or peak, general and local symptoms characteristic of the disease appear. If it goes unfavorably, various complications may occur (for example, coma during diabetes). At the same time, at this stage of development, adaptive mechanisms still continue to operate, although not so effectively to stop the disease on their own.
In that acute period diseases develop the main signs, while some diseases have a more or less definite duration of the course (especially infectious ones), while others, especially chronic ones, do not have this property.
The following forms of diseases are observed:
The exact timing cannot be established, since everything depends on the specifics of the pathology, the intensity and time of exposure of the pathogen to the body, and the endurance of the person himself.
The main periods of the disease are considered. But there is still a stage of recovery or other options for the outcome of the pathology.
There are the following options for the end of the disease: recovery (incomplete and complete), relapse, remission, complication, development into chronic, death.
Full recovery
It consists in the formation of effective adaptive reactions and processes that successfully eliminate the cause and / or pathogenic consequences of the disease, restore the body's self-regulation in full. However, there is no guarantee that the body will return to its pre-morbid state. After recovery, qualitatively and quantitatively different vital signs appear, new functional systems are formed, the activity of metabolism and the immunobiological surveillance system changes, and many other adaptive changes also develop. This is influenced by the main periods of the course of the disease.
Incomplete recovery is characteristic of the body in cases where residual effects of the disease and individual deviations from the norm persist.
relapse
Relapse - re-amplification or re-development symptoms of a disease after they have already been eliminated or weakened. Symptoms are similar to symptoms primary disease, but in some cases there may be differences. Relapse occurs most often due to the action of the causes that caused the initial episode of malaise, a decrease in the effectiveness of adaptive mechanisms or the body's ability to resist any factors. This is typical for periods of infectious diseases.
Remission
Remission is a stage of the disease, which is characterized by temporary mitigation (incomplete, followed by relapse) or elimination (complete) of symptoms. Most often, this period occurs as a consequence or feature of the causes of the disease, or is associated with changes in the patient, as well as with treatment that does not allow to recover completely.
Complication
A complication is a process that develops against the background of a disease, but is not necessarily characteristic of it. Most often, complications arise as a result of the indirect action of the causes of the disease or associated with the components of the process of its course (for example, with an ulcer, perforation of the walls of the intestine or stomach can occur).
Fatal outcome
If the disease develops unfavorably, it is likely that it develops into a chronic, protracted one, as well as such a period of disease development as the death of the patient, when the body is not able to adapt to new conditions, is depleted, and further existence becomes impossible.
The direct cause of death is cardiac arrest, which can be due to both its defeat and disruption of the work of the centers of the brain, which are responsible for the regulation of functions of cardio-vascular system. Another reason is respiratory arrest, which occurs when the respiratory center located in the medulla oblongata is paralyzed, caused by anemia, hemorrhage, tumor, or exposure to poisons such as cyanide, morphine, etc.
stages
Death includes the following stages:
- preagony;
- terminal pause;
- agony;
- clinical death;
- biological death.
The first four stages, subject to timely medical interventions, can be reversible.
Agony is characterized by disturbances in the mechanisms of the central nervous system and changes in all body functions important for life: breathing, heart activity, lowering the temperature, and relaxing the sphincters. Often the patient loses consciousness. This state lasts from several hours to two or three days.
The next stage after agony is clinical death, and it is fundamentally reversible. Signs: cessation of breathing, circulation and heartbeat. This period with normothermia lasts 3-6 minutes, but can be prolonged up to 15-25 minutes with hypothermia. Its duration depends on the degree of hypoxia of neurons located in the cerebral cortex.
At clinical death required to be carried out, which include:
- artificial ventilation of the lungs;
- restoration of blood circulation and cardiac activity, including heart massage, if necessary - defibrillation, start of cardiopulmonary bypass with the use of oxygenated blood;
- adjustment of the acid-base state and restoration of the ionic balance;
- improvement of the state of the system of self-regulation and microcirculation of the body.
After the organism manages to be revived, it is for some time in an unstable post-resuscitation state, which includes the following stages:
- temporary regulation of the vital activity of the organism;
- transient destabilization;
- life improvement and recovery.
Biological death is the termination of a person's life, which is irreversible. A holistic revival of the body is no longer possible, but the possibility of resuming the work of some organs remains. Thus, although the stages of the disease are conditional, such a classification is used quite widely.
We examined the main periods of the disease.
A feature of an infectious disease is its cyclicity. This means that several consecutive periods are distinguished in the development of an infectious disease: incubation, initial, peak of the disease and recovery. Each period has its own characteristics.
The period of time from the moment of infection to the first clinical manifestations of the disease is called incubation (latent). Different infectious diseases have different duration of this period (from several hours to months and even years). At this time, there are usually no visible health problems. For some diseases (measles, malaria, tonsillitis, chickenpox etc.) duration incubation period so strictly defined that it is one of the most characteristic features of this disease (see section "Description of clinical signs").
The initial period is the time from the moment the first signs of the disease appear to its height.
In the initial period, as a rule, there are no characteristic signs inherent in a particular disease. Dominated general symptoms diseases (fever, malaise, general weakness, decreased performance, etc.).
As the infection develops, symptoms characteristic of the disease appear. This moment marks the beginning of the period of the peak of the disease. In the future, many signs can reach their maximum severity.
From the moment the severity of the manifestations of an infectious disease decreases, a period of recovery (reconvalescence) begins, the duration of which depends on many factors: past illness comorbidities, characteristics of the body, as well as the quality of the treatment and the volume of rehabilitation measures performed).
Sometimes, after an infectious disease, there are residual effects that occur during the peak period, but persist for many months, years, and even throughout life (with poliomyelitis, encephalitis, diphtheria, etc.)
With most infectious diseases, a person becomes dangerous to others at the end of the incubation period. Only in the recovery period, the degree of risk of infection from the patient is significantly reduced. In the same period, a complete cleansing of the body from the pathogen begins.
In the development of the disease, four periods (stages) are usually distinguished: latent, prodromal, the period of the height of the disease and the outcome, or the period of the end of the disease. Such a periodization has developed in the past with clinical analysis acute infectious diseases (typhoid fever, scarlet fever, etc.). Other diseases (cardiovascular, endocrine, tumors) develop according to other patterns, and therefore the above periodization is of little use to them. A. D. Ado identifies three stages in the development of the disease: the onset, the stage of the disease itself, and the outcome.
latent period(in relation to infectious diseases - incubation) lasts from the moment of exposure to the cause until the first clinical signs of the disease appear. This period can be short, as with the action of chemical warfare agents, and very long, as with leprosy (several years). During this period, the body's defenses are mobilized, aimed at compensating possible violations, to destroy disease-causing agents or to remove them from the body. It is important to know the features of the latent period when carrying out preventive measures (isolation in case of infection), as well as for treatment, often effective only in this period (rabies).
prodromal period- this is the length of time from the first signs of the disease to the full manifestation of its symptoms. Sometimes this period manifests itself clearly ( lobar pneumonia, dysentery), in other cases it is characterized by the presence of weak, but clear signs of the disease. With mountain sickness, for example, this is causeless fun (euphoria), with measles - spots of Velsky - Koplik - Filatov, etc. All this is important for differential diagnosis. At the same time, the identification of the prodromal period in many chronic diseases is often difficult.
The period of pronounced manifestations, or the height of the disease, is characterized by the full development of the clinical picture: convulsions with parathyroid insufficiency, leukopenia with radiation sickness, a typical triad (hyperglycemia, glycosuria, polyuria) in diabetes mellitus. The duration of this period for a number of diseases (croupous pneumonia, measles) is relatively easy to determine. At chronic diseases with their slow flow, the change of periods is elusive. In diseases such as tuberculosis, syphilis, the asymptomatic course of the process alternates with its exacerbation, and new exacerbations sometimes differ markedly from the primary manifestations of the disease.
Outcome of the disease. The following outcomes of the disease are observed: recovery (complete and incomplete), relapse, transition to a chronic form, death.
Recovery- a process that leads to the elimination of disorders caused by the disease, and the restoration of normal relations between the body and the environment, in humans - primarily to the restoration of working capacity.
Recovery can be complete or incomplete. Full recovery- this is a state in which all traces of the disease disappear and the body fully restores its adaptive capabilities. Recovery does not always mean a return to the original state. As a result of the disease, changes in various systems, including the immune system, may appear and persist in the future.
With incomplete recovery the consequences of the disease are expressed. They remain for a long time or even forever (fusion of the pleura, narrowing of the mitral orifice). The difference between complete and incomplete recovery is relative. Recovery can be almost complete, despite a persistent anatomical defect (for example, the absence of one kidney, if the second completely compensates for its function). It should not be thought that recovery begins after the previous stages of the disease have passed. The healing process begins from the moment the illness occurs.
The idea of the mechanisms of recovery is formed on the basis of general position about the fact that the disease is the unity of two opposite phenomena - the actual pathological and protective-compensatory. The predominance of one of them decides the outcome of the disease. Recovery occurs when the complex of adaptive reactions is strong enough to compensate for possible violations. Of the mechanisms of recovery, urgent (emergency) and long-term are distinguished. The urgent ones include such reflex defense reactions as changes in the frequency of respiration and heart rate, the release of adrenaline and glucocorticoids during stress reactions, as well as all those mechanisms that are aimed at maintaining the constancy of the internal environment (pH, blood glucose, blood pressure, etc.). d.). Long-term reactions develop somewhat later and act throughout the disease. This is primarily the inclusion of reserve capabilities of functional systems. Diabetes mellitus does not occur when even 3/4 of the pancreatic islets are lost. A person can live with one lung, one kidney. Healthy heart under load, it can do five times more work than at rest.
Strengthening of the function increases not only due to the inclusion of structural and functional units of organs that did not work before (for example, nephrons), but also as a result of an increase in the intensity of their work, which in turn causes the activation of plastic processes and an increase in the mass of the organ (hypertrophy) to a level where the load for each functioning unit does not exceed the normal.
The inclusion of compensatory mechanisms, as well as the termination of their activity, depends primarily on the nervous system. P. K. Anokhin formulated the concept of functional systems that specifically compensate for a functional defect caused by damage. These functional systems are formed and work according to certain principles:
Signaling about the violation that has occurred, leading to the activation of the corresponding compensatory mechanisms.
Progressive mobilization of spare compensatory mechanisms.
Reverse afferentation about the successive stages of the restoration of impaired functions.
The formation in the central nervous system of such a combination of excitations that determines the successful restoration of functions in the peripheral organ.
Assessment of the adequacy and strength of the final compensation in dynamics.
The collapse of the system as unnecessary.
The sequence of compensation stages can be traced on the example of lameness when one leg is damaged:
signaling of imbalance from the vestibulocochlear organ;
restructuring of the work of motor centers and muscle groups in order to maintain balance and the possibility of movement;
caused by a stable anatomical defect, constant combinations of afferentations entering the higher parts of the central nervous system, and the formation of temporary connections that provide optimal compensation, i.e., the possibility of walking with minimal lameness.
relapse- a new manifestation of the disease after an apparent or incomplete cessation of it, for example, the resumption of attacks of malaria after a more or less long interval. Observe relapses of pneumonia, colitis, etc.
Transition to the chronic form means that the disease proceeds slowly, with long periods of remission (months and even years). This course of the disease is determined by the virulence of the pathogen and mainly by the reactivity of the organism. So, in old age, many diseases become chronic (chronic pneumonia, chronic colitis).
Terminal States- the gradual cessation of life even with seemingly instantaneous death. This means that death is a process, and several stages (terminal states) can be distinguished in this process: pre-agony, agony, clinical and biological death.
preagony can be of different duration (hours, days). During this period, there is shortness of breath, a decrease in blood pressure (up to 7.8 kPa - 60 mm Hg and below), tachycardia. A person has a blackout of consciousness. Gradually pre-agony turns into agony.
Agony(from the Greek. agon - fight) is characterized by a gradual shutdown of all body functions and at the same time by an extreme tension of protective mechanisms that are already losing their expediency (convulsions, terminal respiration). Duration of agony - 2 - 4 minutes, sometimes more.
Clinical death is a condition when all visible signs of life have already disappeared (breathing and heart function have stopped, but the metabolism, although minimal, is still ongoing). At this stage, life can be restored. That is why the stage of clinical death attracts special attention of clinicians and experimenters.
Biological death is characterized by irreversible changes in the body.
Experiments on animals, primarily on dogs, made it possible to study in detail the functional, biochemical, and morphological changes at all stages of dying.
Dying is the disintegration of the integrity of the organism. It ceases to be a self-regulating system. At the same time, systems that unite the body into a single whole are first destroyed, first of all - nervous system. At the same time, the lower levels of regulation are preserved to some extent. In turn, there is a certain sequence of dying various departments nervous system. The most sensitive to hypoxia is the cortex big brain. With asphyxia or acute blood loss, neuronal activation is first observed. In this regard, there is motor excitation, increased respiration and heart rate, increased blood pressure. Then inhibition occurs in the cortex, which has a protective value, since for some time it can save cells from death. With further dying, the process of excitation, and then inhibition and exhaustion, spreads lower, to the brain stem and reticular pharmacy. These phylogenetically older parts of the brain are the most resistant to oxygen starvation (centers medulla oblongata can tolerate hypoxia for 40 minutes).
In the same sequence, changes occur in other organs and systems. With fatal blood loss, for example, during the first minute, breathing sharply deepens and quickens. Then its rhythm is disturbed, the breaths become either very deep or superficial. Finally, the excitation of the respiratory center reaches a maximum, which is manifested especially deep breathing, which has a pronounced inspiratory character. After that, breathing weakens or even stops. This terminal pause lasts 30.-60 s. Then breathing resumes temporarily, acquiring the character of rare, at first deep, and then more and more superficial breaths. Together with the respiratory center, the vasomotor center is activated. Vascular tone increases, heart contractions increase, but soon stop and vascular tone decreases.
It is important to note that after the cessation of the work of the heart, the system that generates excitation continues to function for quite a long time. On the ECG, biocurrents are noted within 30 - 60 minutes after the disappearance of the pulse.
In the process of dying, characteristic changes in metabolism occur, mainly due to the ever-deepening oxygen starvation. Oxidative metabolic pathways are blocked and the body obtains energy from glycolysis. The inclusion of this ancient type of metabolism has a compensatory value, but its low efficiency inevitably leads to decompensation, aggravated by acidosis. Clinical death occurs. Breathing stops, blood circulation stops, reflexes disappear, but the metabolism, although at a very low level, still continues. This is enough to maintain the "minimal life" of nerve cells. This explains the reversibility of the process of clinical death, i.e., in this period, revival is possible.
A very important issue is the time frame during which resuscitation is possible and appropriate. After all, revival is justified only in the case of restoration of mental activity. V. A. Negovsky and other researchers argue that positive results can be achieved no later than 5-6 minutes after the onset of clinical death. If the process of dying continues for a long time, leading to the depletion of the reserves of creatine phosphate and ATP, then the period of clinical death is even shorter. On the contrary, with hypothermia, revival is possible even an hour after the onset of clinical death. In the laboratory of N. N. Sirotinin, it was shown that a dog can be revived 20 minutes after death as a result of bleeding, followed by a complete restoration of mental activity. However, it should be borne in mind that hypoxia causes greater changes in the human brain than in the brain of animals.
Resuscitation, or revitalization, of the body includes a number of activities that are primarily aimed at restoring blood circulation and respiration: heart massage, artificial ventilation of the lungs, defibrillation of the heart. The latter event requires the availability of appropriate equipment and can be carried out under special conditions.
Etiology. The concept of the causes and conditions of the onset of the disease. Classification of the causes of diseases. The role of heredity and constitution in the occurrence and development of the disease.
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