Acute respiratory viral infections (ARI) - a group highly contagious infections, accompanied by the development of infectious toxicosis, mainly affecting the respiratory system, and often other vital organs and systems (nervous, cardiovascular, liver and others.).
SARS on its specific gravity occupy a leading place in the structure of infectious diseases.WHO experts say in recent years, a steady increase in the incidence of SARS.
registered in Russia every year from 27.3 to 47.2 million cases of influenza and SARS.The share of SARS and influenza accounted for 90% of the total amount of temporary disability among all infectious diseases payments.
reasons for the high incidence of SARS in the Russian Federation:
- lack of adequate mass immunization and immunorehabilitation;
- irrational and uncontrolled use of antibiotics;
- poor nutrition, adverse environmental factors that reduce the immune defense of the child;
- short duration of immunity to a variety of viruses.
Children first six months of
most susceptible to SARS, children with chronic pathology of upper respiratory tract, with an anomaly of the respiratory tract, respiratory allergies, immunodeficiency.
SARS in turn contribute to the formation of chronic diseases of the respiratory tract and LOP-bodies, dramatically modify the reactivity of the child's organism, reduce general and local immunity, favored the development of allergic diseases, a significant effect on the mental and physical development.
etiological structure of ARI (acute respiratory infection)
Viral infections (90-95%):
• Influenza viruses are A1, A2, B, C;
• avian influenza;
• parainfluenza viruses;
• respiratory syncytial virus.
• Coxsackie viruses;
• ECHO viruses;
• infection of herpes simplex virus;
• viruses of herpes zoster;
• Epstein-Barr virus.
7. Intracellular Parasites:
8. Bacterial infections (7-10%):
• atypical mycobacteria.
11. Mixed infection (25%).
• RNA containing human metapneumovirus paramyxovirus family, which causes people in 2,2-33,3% of ARI, at 1.2% of those possible healthy carrier;:
new pathogens of acute respiratory infections were found and described in the first decade of the XXI century
• Human bokavirus causing at 1,5-19% of patients ARI, 1% of people - healthy carrier;
• human coronavirus, which causes not only acute respiratory infections, and atypical pneumonia;
• new influenza virus type A / California / 04/09, caused the pandemic in 2009-2010.
pathogenesis of acute respiratory diseases.The pathogenesis of acute respiratory infections is a fairly complex process of interaction between micro- and macro-organisms under the influence of environmental factors.The influenza virus has pathogenicity factors such as the haemagglutinin (ND-13) and neuraminidase (N1-10), bacteria -. endo- and exotoxins, adhesins, kolitsinogenami, neuraminidase, etc. On the other hand, the important role played by the state of microorganism.Risk groups include the following:
• Burdened obstetric and extragenital history of the mother.
• Perinatal Pathology of the child (hypoxia, birth trauma, malformations and others.).
• Intrauterine infection.
• immunodeficiency states.
• allergic phenotype.
• Artificial feeding.
1. The introduction of the pathogen into the upper respiratory tract.Breathing large amounts of pathogens and contaminating agents get on the mucous membranes of the respiratory tract, but most children trachea and lower divisions remain sterile.In the merit of the anatomical and physiological adaptations (mucociliary transport), nonspecific protection factors (non-specific viral inhibitors, lysozyme, alveolar macrophages interacting with surfactant), factors of local and general immunity.Caught pathogens undergo immediate destruction or remain in the upper tract, settling as the saprophytes.
The alternative - the development of an infectious process.To implement it, you need to get into the respiratory tract of a sufficiently large number of agents having highly virulent and toxigenic properties.In addition, some important state of microorganism, namely:. The presence of chronic foci of infection in the respiratory tract and LOP-organs, abnormal development in these systems, the allergic phenotype, etc.
Pathogens ARI selectively affect the epithelium of the respiratory tract.Develop adhesion and colonization by microorganisms epithelium.Reduced mucociliary clearance products and excretory enzymes help pathogens to resist the muco-ciliary transport.Reproduction pathogens can occur in the intestinal mucosa, lymph nodes.
Massive output agents is often accompanied by loss of epithelial cells, and epithelial necrosis and consequent destruction of the natural barrier leads to viremia.
2. viremia, toxic and toksikoallergicheskie reaction.From the primary localization of the pathogens and their toxins and decomposition products of epithelial cells into the blood, exerting a toxic effect on the cardiovascular, central and autonomic nervous system, urinary tract and other systems.
high concentration of toxins is observed in the intermediate area of the brain, particularly the hypothalamus and the pituitary gland, which is related to their maximum vascularization.In connection with the abundant blood supply to this area and closely adjacently to likvoroprovodyaschim paths, as well as neuro-autonomic, neuroendocrine, and neurohumoral regulation in the first hours of the disease arises a complex set of functional disorders of the nervous system and its regulatory mechanisms of internal organs and metabolic processes.The most prominent clinical manifestations of this are temperature reaction, headache, nausea, dizziness, loss of appetite, general weakness.The defeat of the vascular wall, while the impact of toxic products in the vascular plexus of the brain receptors promotes hypersecretion CSF, the development of cerebral circulatory disorders, cerebral edema and intracranial hypertension.
circulatory disorders which are due to changes in tone, elasticity and permeability of vascular wall under the influence of pathogens toxins underlie the defeat of various organs and systems, including the kidneys, myocardium, lungs.
parallel processes develop sensitization autoallergenami (decay products of epithelial cells), antigens of pathogens.Patients with a history of adverse it may lead to the formation of autoimmune and allergic reactions and the development of clinical manifestations (allergic rhinitis, constrictive obstructive bronchitis, atopic dermatitis, diarrhea).
3. Development of serous inflammation in the lining of the upper respiratory tract, the immune response, induction of systemic and local CID.Depending on the type of pathogens affected a particular department of the respiratory tract, may spread to the lower sections, as well as a process involving the gastrointestinal tract, the lymphatic system.In addition to epithelial cells affects the subject tissue, blood vessels.Formed local inflammatory reaction (rhinitis, faringotonzillit, tracheitis, etc.).
addition to mechanical factors (mucociliary clearance, cough, bronchoconstriction) an important role in the anti-infective protection factors play an innate resistance and immune response of cellular and humoral type.Innate (nonspecific) provide resistance humoral factors (lysozyme, transferrin, fibronectin, defensins, complement, properdin, interferons) and a number of cells - macrophages, neutrophils, natural killer cells (CD 16).Humoral immune response type is primarily in the development of secretory IgA, which binds extracellular viruses, toxins and allergens, opsonizing bacteria on mucous membranes.During a humoral immune response occurs starting synthesis IgM class antibodies, followed by switching to IgG.The elimination of intracellular pathogens (viruses, chlamydia, mycoplasma) involved cal cytotoxic T-lymphocytes (CD8).The etiological agents of ARI cause violation of mucociliary clearance, interferon status, generating humoral factors of innate resistance, the functional activity of macrophages, natural killer cells, and neutrophils.In addition, there is suppression of the immune response by the humoral and cell types.
4. The development of bacterial inflammation and complications.As a result, the induction of local and systemic CID is activated TPC to form viral-bacterial and viral-bacterial-fungal association, leading to the development of purulent inflammation in the mucosa of the respiratory tract and the emergence of bacterial complications (pneumonia, tonsillitis, otitis, sinusitis, adenoiditis meningitispyelonephritis, myocarditis, sepsis, and others.).There reactivation of opportunistic infections (herpes viruses, chlamydia, mycoplasma, and others.).On the other hand, there is a start-allergic infectious processes.In children with atopic phenotype, the formation of allergic inflammation as a result of an imbalance of immunoregulatory subpopulations of T-helper cells.Amid Th 1 and inhibition of interferon-y activity of Th2 predominance is observed, the synthesis of large amounts of inte-interleukin-4, which leads to overproduction of IgE.The clinical manifestations of allergic inflammation are constrictive laryngotracheitis, obstructive bronchitis and others. Repeated episodes of these conditions can lead to the development of asthma.
5. Outcomes.Given the characteristics of pathogens and the condition of the body outcomes of acute respiratory infections may be recovery, persistence of pathogens, the formation of chronic respiratory diseases, allergic phenotype and others.
Specific laboratory diagnosis of respiratory viral infections includes the complex virologic and immunologic methods.
Virological diagnostic methods based on virus isolation in eggs, laboratory animals (mice, rats, ferrets, etc.) And in tissue cultures.The most widely used method for virus isolation in chicken embryos by infecting them with the test material in the amniotic or allantoic cavity.For virological investigations take nasal discharge, blood, in patients with suspected infection of adenovirus - further discharge from the conjunctiva, feces, with enterovirus infection - feces, cerebrospinal fluid.The most likely virus isolation in the first 2-3 days of onset.
Rapid methods based on indication of viral antigen in cell discharge cells of the nasal mucosa.
fluorescent microscopy method is based on the ability of fluorochrome acridine binding to RNA, to give compounds of bright red color.The method detects RNA incorporating 60% of patients with influenza, but can not differentiate Viru * influenza types A, B, C.
immunofluorescence method is based on the specific binding of the antigen with antibodies labeled with fluorescein.Diagnosis of viral respiratory infections up to 70%.The material for the study are smears with inferior turbinate.
Serologic methods are based on the qualitative and quantitative detection of specific antiviral antibodies in the blood.The main methods are RAC, PH and HI.The study was conducted twice, at 6-7-th day of the disease and on the 14th day.Significant diagnostic value has increase in titer 4 times or more.
ELISA and RIA methods are highly sensitive and allow you to define klassospetsifichesky immune response that eliminates the need for the study of paired sera.
Differential diagnosis of acute respiratory infections in children.Leading respiratory syndrome virus infections is catarrhal, including rhinitis, pharyngitis, laryngitis, tracheitis, which can occur in isolation, but also in various combinations.
Catarrhal syndrome can be detected at a number of diseases:
I. Acute respiratory infections of viral etiology: influenza, parainfluenza, adenovirus, rhinovirus, reovirus, respiratornosintsitialnaya, coronavirus, enterovirus, cytomegalovirus infection, infection of herpes simplex virus.
II.Infectious diseases of bacterial etiology, occurring with respiratory tract lesions: chlamydia, mycoplasmosis, legionellosis, streptococcal, staphylococcal, meningococcal infections, whooping cough, parakoklyush.
III.Infectious diseases of viral etiology, occurring with lesions of the upper respiratory tract: measles, rubella.
IV.Exacerbation of chronic foci of infection in the upper respiratory tract: chronic pharyngitis, chronic rhinitis, chronic sinusitis.
V. Allergic lesions of the respiratory tract: allergic rhinitis, allergic pharyngitis, allergic tracheitis.
VI.Defeat airway chemical agents.
complications in patients with acute respiratory infections can occur in any period of time from the onset of the disease.The frequency of complications ranges from 30 to 60%.
Morbidity ARI is more often observed in patients with poor premorbid background (malnutrition, anemia, poor feeding, VAT, etc.).Clinically significant complications tend to have viral and bacterial origin.There is a connection of exogenous or endogenous activation of the infection.
most common complications arise from the respiratory system.Bronchitis viral and bacterial etiology often form in patients with chronic foci of infection in the nasopharynx, with stenotic laryngotracheobronchitis, functional disorders of the mucociliary transport.Eligibility of a bacterial infection in the etiology of bronchitis: prolonged fever, purulent sputum, peripheral blood - leukocytosis with neutrophilia and shift to the left in bronchograms - marked reduction in the number of macrophages and increased neutrophils.
lung tissue involved in the process at a respiratory virus, mycoplasma, chlamydia infections with approximately the same frequency.Moreover, in 5-8% of patients treated on an outpatient basis, and in 13-19% of patients treated at the hospital.
pneumonia developing in patients with acute respiratory infections in the hospital, due to the addition of most gram-negative flora (Klebsiella, E. coli, Haemophilus influenzae, Pseudomonas) and hospital strains of Staphylococcus aureus, pneumococcus.Diagnosis is performed based pneumonia clinical signs of respiratory data radiographs.Usually diagnosed focal or segmental pneumonia.Clinical manifestations of pneumonia, the severity depends on the timing of involvement in the lung tissue, the pathogen of ARI.Thus, the frequency of pneumonia, developed in the early days of ARI, the highest, and the severity of clinical symptoms most prolonged and severe with the participation in the etiology of disease and mycoplasma adenoviruses.Infiltration is the nature of segmental, affects two or more segments of the lung, every third child are manifestations of respiratory insufficiency II-III degree, often develop cardiovascular, dyspeptic and Banti's syndrome.