The generally accepted term “infectious diseases” was introduced by German doctor Christoph Wilhelm Hufeland. Main signs of infectious diseases:
* the presence of a specific pathogen as the direct cause of the disease;
* contagiousness (infectiousness) or the occurrence of several (many) cases of diseases caused by a common source of infection (zoonoses, sapronoses);
* often prone to widespread epidemic spread;
* cyclical course (consecutive change of periods of illness);
* the possibility of developing exacerbations and relapses, protracted and chronic forms;
* development immune reactions to Ag (antigen) of the pathogen;
* the possibility of developing carriage of the pathogen.
Specificity. Each infectious disease is caused by a specific pathogen. Specific pathogens of infectious diseases can be bacteria, rickettsia, chlamydia, mycoplasma, fungi, viruses, and prions. However, infections (for example, purulent-inflammatory processes) caused by various microbes are known.
The cyclical nature of the flow is characteristic of most infectious diseases. It is expressed in the sequential change of certain periods of the disease - incubation (latent), prodromal (initial), the period of main manifestations (the height of the disease), the extinction of symptoms (early convalescence) and recovery (convalescence).
Incubation period is the period from the moment of infection to the appearance of the first signs of the disease. During this period, the body actively reproduces and accumulates the pathogen and its toxins up to a certain threshold amount, after which the body begins to respond with certain clinical manifestations, i.e., the next, prodromal period begins. The duration of the incubation period varies on average from several days to several weeks, but it can be equal to several hours and last several months, and in case of leprosy - several years. This depends on a number of reasons - the magnitude of the infectious dose and the degree of pathogenicity of the pathogen, as well as on the state of resistance of the organism.
Prodromal period, or period of precursors. It is usually characterized by nonspecific, general manifestations- weakness, weakness, headache, general malaise, fever, etc. Its duration varies between 24 - 48 hours.
The period of development (heyday) of the disease. It is also often characterized by a certain cyclicity. There is a stage of increasing symptoms (incrementum stage), flourishing of the disease (aste stage) and a period of fading of symptoms (decrementum stage). In the typical form of the disease, this period is characterized by the manifestation of symptoms specific to the disease, as well as some general symptoms, in particular, fever, intoxication, inflammation, and sometimes the appearance of a rash.
Outcome period. During this period the following may occur:
Relapse of the disease - return clinical manifestations illness without reinfection, due to pathogens remaining in the body;
· Superinfection - infection of a macroorganism with the same pathogen before recovery. If this happens after recovery, then it is called reinfection, because. it occurs as a result of a new infection with the same pathogen, as often happens with influenza, dysentery, and gonorrhea.
· Bacterial carriage, carriage of the causative agent of any infectious disease without clinical manifestations;
· Recovery, or convalescence. Clinical recovery usually occurs earlier than pathological and bacteriological recovery. The person is practically healthy, but some pathoanatomical changes still remain at the site of the localization of the process (for example, after suffering from dysentery on the mucous membrane of the colon). Convalescence can be complete: all processes end completely without any aggravating consequences. However, some diseases leave severe consequences, for example, muscle paralysis after polio, encephalitis; cirrhosis of the liver after viral hepatitis B, etc. Particular attention should be paid to bacteriological recovery after an infectious disease, i.e. complete liberation of the body from the pathogen. For various infectious diseases, the period of bacteriological recovery varies, and this is taken into account when discharging such patients from the hospital. For example, with typhoid fever, up to 80% of convalescents during the first two weeks are bacteria carriers.
· Fatal outcome. It must be remembered that the corpses of infectious patients are subject to mandatory disinfection, because pose a certain epidemiological danger due to the high content of microbial agents in them.
How do infectious patients differ from others, what are the features of infectious diseases? .
For the spread of an infectious disease, 3 conditions are necessary:
An epidemic focus is the location of the source of infection (a sick person or a carrier of infection, an infected animal), as well as the entire territory within which the pathogen can spread from this source of infection.
There is a concept about the intensity of the spread of an infectious disease:
The constant presence of any infectious disease in a particular region is called endemic
Social and everyday factors are of primary importance in the spread of the epidemic - population density, social disasters (war, forced migration, famine), material well-being, health and nutritional status, living conditions and communal amenities (density, availability of water supply and sewerage, ventilation, etc.) the presence of insects, rodents, domestic animals, collection and disposal of waste), the level of sanitary and general culture, and the availability of medical care.
Read also " How do infectious diseases occur?» « The concept of an infectious process» «
Infectious diseases, unlike other diseases, have a number of features.
1. Infectious diseases are characterized by nosological specificity, which lies in the fact that each pathogenic microbe causes its own, unique infectious disease and is localized in a particular organ or tissue. Opportunistic pathogenic microbes do not have this nosological specificity.
According to the etiological principle, infectious diseases are divided into: a) bacteriosis (bacterial infections), b) viral infections; d) mycoses and mycotoxicoses.
2. Infectious diseases are characterized by contagiousness(syn. infectivity. contagiousness). These are, first of all, infectious diseases. Under contagiousness (from lat. contaggiosus - contagious, contagious) refers to the ease with which a pathogen is transmitted from an infected organism to an uninfected one, or the rapidity with which microbes spread among a susceptible population through a chain reaction or fan-shaped transmission.
Infectious diseases are characterized by the presence infectious period- the period of time during an infectious disease when the pathogen can spread directly or indirectly from a sick macroorganism to a susceptible macroorganism, including with the participation of arthropod vectors. The duration and nature of this period are specific to the disease and are determined by the characteristics of the pathogenesis and excretion of the microbe from the macroorganism. This period may cover the entire duration of the illness or be limited to certain periods of the illness and, what is important from an epidemiological point of view, begin already during the incubation period.
To qualitatively assess the degree of contagiousness, use infectiousness index, defined as the percentage of people exposed to the disease over a certain period of time. The infectivity index depends on such variables as the virulence of the microbial strain;
intensity and duration of time of its release from the host’s body; dose and route of distribution; microbial survival environment; degree of susceptibility of the macroorganism. The degree of contagiousness is not the same. Thus, measles is a highly contagious disease, since almost 100% of people who have contact with the patient and do not have immunity to the virus get measles (contagiousness index 0.98). At the same time, less than half of those exposed to the risk of infection contract mumps (infectivity index 0.35-0.40).
3. Infectious diseases are characterized cyclical flow, which consists in the presence of successively changing periods based on the pathogenesis of the disease. The duration of the periods depends both on the properties of the microbe and on the resistance of the macroorganism, and the characteristics of immunogenesis. Even with the same disease different persons The duration of these periods may vary.
The following periods of disease development are distinguished: incubation (latent); prodromal (initial); the period of the main or pronounced clinical manifestations of the disease (the height of the disease); period of extinction of symptoms of the disease (early period of convalescence); recovery period (reconvalescence).
The period from the moment of introduction of the microbe (infection, infection) into the macroorganism until the onset of the first clinical manifestations of the disease is called incubation(from lat. incubo - rest or incubation - without external manifestations, hidden). During the incubation period, the pathogen adapts to the internal environment of the infected macroorganism and overcomes the latter’s defense mechanisms. In addition to the adaptation of microbes, they multiply and accumulate in the macroorganism, move and selectively accumulate in certain organs and tissues (tissue and organ tropism), which are most susceptible to damage. On the part of the macroorganism, already in the incubation period, the mobilization of its protective
strength There are no signs of the disease in this period yet, but with special studies it is possible to detect the initial manifestations of the pathological process in the form of characteristic morphological changes, metabolic and immunological changes, the circulation of microbes and their antigens in the blood. From an epidemiological perspective, it is important that a macroorganism at the end of the incubation period can pose an epidemiological danger due to the release of microbes from it into the environment.
The duration of the incubation period has a certain duration, subject to fluctuations both downward and upward. For some infectious diseases, the incubation period lasts hours, as, for example, with influenza; with others - for weeks and even months, as, for example, with viral hepatitis B, rabies, and slow viral infections. For most infectious diseases, the incubation period is 1-3 weeks.
Prodromal or initial period(from Greek prodromes - precursor) begins with the appearance of the first clinical symptoms of a general disease as a result of intoxication of the macroorganism (malaise, chills, fever, headache, nausea, etc.). There are no characteristic specific clinical symptoms on the basis of which an accurate clinical diagnosis could be made during this period. An inflammatory focus often appears at the site of the entrance gate of infection - primary affect. If regional lymph nodes are involved in the process, then they talk about primary complex.
The prodromal period is not observed in all infectious diseases. It usually lasts 1-2 days, but can be shortened to several hours or extended to 5-10 days or more.
The prodromal period gives way perihome of the main or pronounced clinicalmanifestations of the disease(height period), which is characterized by the maximum severity of general nonspecific symptoms of the disease and the appearance of specific or
absolute (obligate, decisive, pathognomonic), characteristic only of a given infection, symptoms of the disease that allow an accurate clinical diagnosis to be made. It is during this period that the specific pathogenic properties of microbes and the response of the macroorganism find their fullest expression. This period is often divided into three stages: 1) the stage of increasing clinical manifestations (stadium incrementi); 2) stage of maximum severity of clinical manifestations (stadium fastigii); 3) stage of weakening of clinical manifestations (stadium decrementi). The duration of this period varies significantly for different infectious diseases, as well as for the same disease in different individuals (from several hours to several days and even months). This period may end fatally, or the disease progresses to the next period, which is called period of symptoms fadingillness (early period of convalescence).
During the period of extinction, the main symptoms of the disease disappear and the temperature normalizes. This period is replaced period of convalescence(from lat. re - denoting repetition of action and convalescentia - recovery), which is characterized by the absence of clinical symptoms, restoration of the structure and function of organs, cessation of the proliferation of the pathogen in the macroorganism and the death of the microbe, or the process can become a microbial carrier. The duration of the convalescence period also varies widely even for the same disease and depends on its form, severity, immunological characteristics of the macroorganism, and the effectiveness of the treatment.
Recovery can be complete, when all impaired functions are restored, or incomplete, when residual (residual) phenomena remain, which are more or less stable changes in tissues and organs that arise at the site of development of the pathological process (deformations and scars, paralysis, tissue atrophy, etc.) .d.). There are: a) clinical recovery, in which only
visible clinical symptoms of the disease; b) microbiological recovery, accompanied by the release of the macroorganism from the microbe; c) morphological recovery, accompanied by restoration of the morphological and physiological properties of the affected tissues and organs. Typically, clinical and microbiological recovery do not coincide with complete restoration of morphological damage that lasts for a long time. In addition to complete recovery, the outcome of an infectious disease can be the formation of microbial carriage, transition to chronic form course of the disease, death.
For clinical purposes, infectious disease is usually divided by type, severity and course. Under type It is customary to understand the severity of symptoms characteristic of a given nosological form. TO typical forms include cases of illness in which all the leading clinical symptoms and syndromes characteristic of this disease. TO atypical forms include erased, inapparent, as well as fulminant and abortive forms.
At erased forms one or more characteristic symptoms are absent, and the remaining symptoms are usually mild.
Inapparate(syn.: subclinical, latent, asymptomatic) forms occur without clinical symptoms. They are diagnosed using laboratory research methods, usually in foci of infection.
Lightning fast(syn. fulminant, from lat. fulminare - kill by lightning, fulminant, or hypertoxic) forms are characterized by very severe course with rapid development of all clinical symptoms. In most cases, these forms are fatal.
At abortifacients forms, the infectious disease develops typically from the very beginning, but ends suddenly, which is typical, for example, for typhoid fever in vaccinated people.
The course of infectious diseases is distinguished by nature and duration. The nature of the course can be smooth, without exacerbations and relapses, or non-smooth, with exacerbations, relapses and complications. By duration
However, the course of an infectious disease may be sharp, when the process ends within 1-3 months, protracted or sub-postRome with a duration of up to 4-6 months and chronic - over 6 months.
Complications arising from infectious diseases can be divided into specific, caused by the action of the main causative agent of the infectious disease, and non-specific.
4. During infectious diseases occurs formation of immunity, which is a characteristic feature of the infectious process. The intensity and duration of acquired immunity vary significantly in different infectious diseases - from pronounced and persistent, practically excluding the possibility of re-infection throughout life (for example, with measles, plague, smallpox, etc.) to weak and short-term, causing the possibility of re-infection diseases even after a short period of time (for example, with shigellosis). With most infectious diseases, a stable, intense immunity is formed.
The intensity of the formation of immunity during an infectious disease largely determines the characteristics of the course and outcome of the infectious disease. Characteristic featurethe pathogenesis of infectious diseases isdevelopment of secondary immunodeficiency. In some cases, an inadequately expressed immune reaction aimed at localizing and eliminating the microbe takes on an immunopathological character (hyperergic reactions), which contributes to the transition of the infectious process into a chronic form and can put the macroorganism on the brink of death. With a low level of immunity and the presence of microbes in the macroorganism, exacerbations and relapses may occur. Exacerbation- this is an increase in the symptoms of the disease during the period of extinction or the period of convalescence, and relapse- is the occurrence of repeated attacks of the disease during the recovery period after the disappearance of clinical symptoms of the disease. Exacerbations and relapses are observed mainly in long-term infectious diseases.
diseases, for example, typhoid fever, erysipelas, brucellosis, tuberculosis, etc. They arise under the influence of factors that reduce the resistance of the macroorganism, and can be associated with the natural cycle of development of microbes in the macroorganism, as, for example, with malaria or relapsing fever. Exacerbations and relapses can be both clinical and laboratory.
5. To make a diagnosis of infectious diseases, they are used specificmicrobiological and immunological methodsdiagnostics(microscopic, bacteriological, virological and serological studies, as well as bioassays and skin allergy tests), which are often the only reliable way to confirm the diagnosis. These methods are divided into basic And auxiliary(additional), as well as methods express diagnostics.
The main diagnostic methods include methods that are used to make a diagnosis in each examined patient in a comprehensive manner in the dynamics of the disease without fail.
Additional methods allow you to assess the patient’s condition in more detail, and express diagnostic methods allow you to make a diagnosis on early stages, in the first days of illness.
The choice of diagnostic methods is determined by the primary clinical and epidemiological diagnosis and the characteristics of the expected nosological form.
6. For the treatment and prevention of infectious diseases, in addition to etiotropic drugs, which include antibiotics and other antimicrobial drugs, specific drugs, directed directly against this microbe and its toxins. Specific drugs include vaccines, serums and immunoglobulins, bacteriophages, eubiotics and immunomodulators.
Infectious diseases are the most common types of diseases. According to statistics, every person suffers from an infectious disease at least once a year. The reason for such prevalence of these diseases lies in their diversity, high contagiousness and resistance to external factors.
A common classification of infectious diseases is based on the method of transmission: airborne, fecal-oral, household, vector-borne, contact, transplacental. Some of the infections may also be related to different groups, because they can be transmitted in different ways. Based on location, infectious diseases are divided into 4 groups:
Infectious diseases have common features. These features manifest themselves to varying degrees in different infectious diseases. For example, contagiousness chickenpox can reach 90%, and immunity is formed for life, while the infectiousness of ARVI is about 20% and forms short-term immunity. The following features are common to all infectious diseases:
The main cause of infectious diseases are pathogens: viruses, bacteria, prions and fungi, but not in all cases the entry of a harmful agent leads to the development of the disease. The following factors will be important:
It takes some time from the time the pathogen enters the body until complete recovery. During this period, a person goes through the following periods of infectious disease:
Infectious diseases are transmitted in the following ways:
Since the types of infectious diseases are diverse and numerous, to diagnose correct diagnosis Doctors have to use a complex of clinical and laboratory-instrumental research methods. On initial stage diagnostics, an important role is played by collecting anamnesis: history of previous diseases and this one, living and working conditions. After an examination, anamnesis and initial diagnosis, the doctor prescribes a laboratory test. Depending on the suspected diagnosis, this may include various blood tests, cell tests and skin tests.
Bacterial diseases are transmitted through infected animals, sick people, contaminated foods, objects and water. They are divided into three types:
Human viral diseases are highly contagious and widespread. The source of the disease is a virus transmitted from a sick person or animal. Infectious disease agents spread rapidly and can affect people over a vast area, leading to epidemic and pandemic situations. They manifest themselves fully in the autumn-spring period, which is associated with weather conditions and weakened human bodies. The top ten common infections include:
Fungal infectious skin diseases are transmitted through direct contact and through contaminated objects and clothing. Most fungal infections have similar symptoms, so diagnosis requires laboratory diagnostics skin scraping. Common fungal infections include:
Among prion diseases, some diseases are infectious. Prions, proteins with an altered structure, enter the body along with contaminated food, through dirty hands, unsterile medical instruments, and contaminated water in reservoirs. Prion infectious diseases in humans are severe infections that are practically untreatable. These include: Creutzfeldt-Jakob disease, kuru, fatal familial insomnia, Gerstmann-Straussler-Scheinker syndrome. Prion diseases affect nervous system and brain, leading to dementia.
The most dangerous infectious diseases are diseases in which the chance of recovery is only a fraction of a percent. In the top five dangerous infections includes:
Prevention of infectious diseases consists of the following components:
“Infectious process” is a phrase that has not surprised anyone for many years. Diseases of this group accompany humanity throughout its existence. To better understand how to protect yourself from infection, it is necessary to take a closer look at this concept and its features.
First, you will become familiar with the main terms. So, an infection is not a disease yet. It represents only the moment of infection. It covers the entry of the pathogen into the body and the beginning of its development.
The infectious process is the state in which you are after infection. That is, it is a kind of reaction of the body to those pathogenic bacteria that have begun to multiply and inhibit the functioning of the systems. He is trying to free himself from them, to restore his functions.
An infectious process and an infectious disease are almost the same concepts. However, the latter term implies the manifestation of the body's condition in the form of symptoms and signs. In most cases, the disease ends with recovery and complete destruction of harmful bacteria.
The infectious process has certain features that distinguish it from other pathological phenomena. Among them are the following:
1. High degree contagiousness. Every sick person becomes a source of pathogens for other people.
1. Air. Most often, pathogens enter the respiratory system, where they begin to multiply. They are transmitted to another person when talking, sneezing, and even penetrate into the body with dust.
2. Fecal-oral. The place of localization for such microorganisms is the stomach and intestines. Microbes enter the body through food or water.
3. Contact. Such diseases often affect skin, mucous membrane. Hand over pathogenic microflora in this case, you can touch healthy person or when using contaminated items.
4. Transmissive. It involves the localization of harmful microorganisms in the blood. In this case, the infection is transmitted by insects, such as mosquitoes.
5. Transplacental. This route involves the passage of germs and bacteria from mother to child through the placenta.
6. Artificial. In this case, the infection is introduced into the body as a result of any manipulation: in a hospital, tattoo parlor, beauty salon and other establishments.
7. Sexual, that is, through sexual contact.
As you can see, if you follow the rules of hygiene, you can avoid many problems.
It must be said that pathology may not always manifest itself. The infection can live in the human body for a very long time without making itself felt. These are the so-called “hidden infections”. Most often they are transmitted sexually. The first symptoms may appear only after a week. During this time, microorganisms already cause serious harm to all human systems.
Such infections include: chlamydia, syphilis, gonorrhea, trichomoniasis. In addition, herpes, papillomaviruses, and cytomegalovirus can also be included here. A person can live without even knowing that these problems exist. Often pathology can only be detected using special tests. Hidden infections are very insidious, so you should take care of yourself and try not to become infected with them.
There are several stages of therapy:
1. Impact on the pathogen using antibacterial, antiviral, antifungal drugs and antibiotics.
2. Prevention further development process. This is done with the help of detoxification therapy, taking anti-inflammatory drugs, immunomodulators, and multivitamins.
3. Elimination of symptoms.
Flow infectious process can be very severe, so you cannot always do without medical help.
Taking precautions will not only help you stay healthy and happy, but will also protect you from possible serious complications. Prevention is quite simple:
1. Proper nutrition And active image life.
2. Refusal bad habits: smoking, drinking alcohol.
3. Maintaining an orderly sex life.
4. Protecting the body with special medical supplies during the height of the infection.
5. Constant implementation of all necessary hygiene procedures.
6. Timely contact a doctor in case of any problems.
That's all the features of the infectious process. Be healthy and take care of yourself.
