Infectious diseases. Acute respiratory diseases. Flu. Parainfluenza. Etiology, epidemiology, pathogenesis, clinical picture, diagnosis, treatment (lecture notes)

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Infectious diseases. Acute respiratory diseases. Flu. Parainfluenza. Etiology, epidemiology, pathogenesis, clinical picture, diagnosis, treatment (lecture notes)

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LECTURE No. 14. Acute respiratory diseases. Flu. Parainfluenza. Etiology, epidemiology, pathogenesis, clinic, diagnostics, treatment

1. Acute respiratory diseases

Acute respiratory diseases (ARI, acute respiratory viral infections, ARVI) are widespread, characterized by general intoxication and predominant damage to the mucous membranes of the respiratory tract. They belong to anthroponotic infections with an airborne transmission mechanism. Children get sick more often. They occur as sporadic cases and epidemic outbreaks.

Etiology. ORZ are caused by:

1) influenza viruses of various antigenic types and variants;

2) parainfluenza viruses - four types;

3) adenoviruses - thirty-two types;

4) reoviruses - three types;

5) rhinoviruses - over a hundred types;

6) coronaviruses - four types;

7) respiratory syncytial virus;

8) enteroviruses - about seventy types;

9) herpes simplex virus.

The main bacterial pathogens of acute respiratory infections are opportunistic pneumotropic microorganisms (streptococci, staphylococci, mycoplasmas, chlamydia, etc.).

Pathogenesis. The entrance gates of infection are various parts of the respiratory tract, where inflammatory changes occur.

The clinic is characterized by moderately severe symptoms of general infectious intoxication, fever, syndrome of damage to the upper respiratory tract at various levels and local inflammatory changes in the form of rhinitis, pharyngitis, laryngitis, tracheitis, bronchitis and their combinations. The localization of the most pronounced changes in the respiratory tract depends on the type of pathogen. For example, rhinoviral diseases are characterized by a predominance of rhinitis, adenoviral diseases - nasopharyngitis, parainfluenza is manifested by a predominant lesion of the larynx, influenza - the trachea, respiratory syncytial viral disease - the bronchi. Some etiological factors, in addition to damage to the respiratory tract, lead to other symptoms. The consequence of adenoviral diseases can be conjunctivitis and keratitis, with enteroviral diseases - signs of epidemic myalgia, herpangina, exanthema. The duration of acute respiratory infections not complicated by pneumonia usually ranges from 2-3 to 5-8 days. If there are inflammatory changes in the lungs, the disease may drag on for 3-4 weeks.

Rhinitis is subjectively felt in the form of a runny nose, a feeling of nasal congestion and itching, and sneezing. Rhinoscopy reveals hyperemia, swelling of the nasal mucosa, the presence of serous, mucous or mucopurulent discharge in the nasal passages. Pharyngitis is manifested by dryness, sore throat, coughing, and pain when swallowing. Pharyngoscopy reveals hyperemia of the mucous membrane of the posterior and lateral walls of the pharynx, mucous or mucopurulent discharge along the posterior wall of the pharynx, hyperplasia or hypertrophy of the tonsils. Hyperemia, granularity and injection of blood vessels in the mucous membrane of the soft palate are typical. Laryngitis is characterized by complaints of hoarseness, a rough, “barking” cough, soreness and soreness in the throat, which worsens with coughing. Laryngoscopy reveals diffuse hyperemia of the laryngeal mucosa, hyperemia and infiltration of the vocal cords, incomplete closure of the vocal cords during phonation, and the presence of viscous mucus in the larynx. Tracheitis is characterized subjectively by the patient as rawness and burning behind the sternum, aggravated by coughing. The cough at the beginning of the disease is dry, unproductive and painful, not bringing relief to the patient; after a while, sputum appears. When auscultating hard breathing, wheezing may be heard, which quickly disappears when coughing up sputum. Bronchitis is characterized by the presence of a dry or wet cough with the discharge of mucous or mucopurulent sputum. On auscultation, harsh breathing and moist or dry rales are heard throughout all lung fields. An X-ray examination of the chest organs can detect an increase in the pulmonary pattern.

Differential diagnosis of acute respiratory infections is difficult; therefore, in the work of a practicing physician, the etiological characteristics of the disease often remain undisclosed. During epidemic outbreaks, the characteristic clinical picture suggests the presence of the disease. Confirmation of the diagnosis is an increase in the titer of specific antibodies in paired sera. The first serum is taken before the 6th day of illness, the second - after 10-14 days.

The diagnosis is confirmed by an increase in titers by 4 times or more. Use RSK and RTGA. Detection of pathogens using the immunofluorescent method is a quick method for deciphering the etiology of diseases. Similar clinical manifestations of past diseases leave behind only type-specific immunity. Because of this, the same person can endure acute respiratory infections 5-7 times during the year. This is especially true in children's groups.

Treatment. For uncomplicated acute respiratory infections, patients are treated at home. Hospitalization is subject to patients with severe and complicated forms of the disease, as well as persons from organized groups. Antibacterial drugs are prescribed only with the addition of a bacterial infection and the presence of microbial complications (otitis media, pneumonia, sinusitis, etc.). During the febrile period, the patient must comply with bed rest. Vitamin therapy is prescribed (vitamin C - up to 300 mg). To reduce cough use steam inhalation, expectorants. With severe rhinitis, galazolin, naphthyzin, sanorin, etc. are instilled into the nose. If necessary, other symptomatic agents are prescribed. You can use antigrippin, which is a complex of symptomatic drugs. In severe forms of the disease, it is possible to administer normal human immunoglobulin (gamma globulin) in the first days of the disease, 6 ml o/w. With the development of false croup syndrome in children, it is necessary to moisten the air in the room (hang wet sheets, put dishes with warm water), apply warm or hot compresses to the neck area.

The prognosis is favorable. The average duration of disability is 5-7 days.

Prevention. Isolation of the patient from others, the allocation of individual dishes that should be disinfected. Activities in the foci of infection are the same as with influenza. Preventive measures also include hardening, restorative procedures, a full-fledged summer vacation, a healthy lifestyle (observance of the daily routine, regular walks, age-appropriate sleep, eating fresh fruits, garlic and onions).

2. Flu

Influenza is an anthroponotic disease of a viral nature. It is characterized by an acute onset, fever, symptoms of general intoxication and damage to the respiratory tract, and is transmitted by airborne droplets.

Etiology. The causative agents of influenza are RNA viruses that belong to the orthomyxovirus family, which includes the genus of influenza A viruses, the genus of influenza B and C viruses. Influenza A viruses are divided into many serotypes. New antigenic variants are constantly emerging. The influenza virus has a spherical shell covered with spines formed by two glycoproteins: neuraminidase, which is a protein enzyme that facilitates the penetration of the virus into the host cell, and hemagglutinin, a protein. The influenza virus is quickly killed by heating, drying and under the influence of various disinfecting agents.

Pathogenesis. The portal of infection is the upper parts of the respiratory tract. The influenza virus selectively infects the columnar epithelium of the respiratory tract, especially the trachea. By multiplying in columnar epithelial cells, it causes their degenerative changes, using the contents of epithelial cells to build new viral particles. Also, the release of mature viral particles is accompanied by the death of epithelial cells, and necrosis of the epithelium and the associated destruction of the natural protective barrier leads to viremia. The toxins of the virus, together with the decay products of epithelial cells, have a toxic effect on the cardiovascular, nervous and other systems of the body. Damage to various organs and systems during influenza is often caused by circulatory disorders, which are the result of disturbances in the tone, elasticity and permeability of the vascular wall. Increased permeability of vessel walls leads to impaired microcirculation and the occurrence of hemorrhages (hemoptysis, nosebleeds, hemorrhagic pneumonia). Flu helps reduce immunological reactivity. This leads to an exacerbation of various chronic diseases - rheumatism, chronic pneumonia, pyelitis, cholecystitis, dysentery, toxoplasmosis, as well as the occurrence of secondary bacterial complications. The virus persists in the patient’s body for 3-5 days from the onset of the disease, and when complicated by pneumonia - up to 10-14 days.

Epidemiology. The disease is ubiquitous. The reservoir of infection is a sick person who is dangerous to others from the end of the incubation period and the entire febrile period. The incubation period lasts from 12 to 48 hours. The route of transmission is airborne. Susceptibility to influenza is universal. After an infection, type-specific immunity is formed. Classification: typical course and atypical course; according to the severity of the course: mild, moderate, severe forms.

Clinic. A typical flu begins acutely, often with chills or chills, the body temperature rises rapidly, and already on the first day the fever reaches its maximum level (38-40 ° C). There are signs of general intoxication (weakness, weakness, sweating, muscle pain, severe headache, eye pain) and symptoms of respiratory tract damage (dry cough, sore throat, rawness behind the sternum, hoarseness). Examination reveals flushing of the face and neck, injection of scleral vessels, increased sweating, bradycardia, and a decrease in blood pressure. Revealed the defeat of the upper respiratory tract in the form of rhinitis, pharyngitis, laryngitis, tracheitis. The trachea is more commonly affected, while rhinitis may be absent. Characterized by hyperemia and a kind of granularity of the mucous membrane of the pharynx. The tongue is coated, there may be a short-term liquid stool. Complications from the side of the central nervous system are expressed in the form of meningism and encephalopathy. Characterized by leukopenia, neutropenia, ESR in normal cases is not increased. Mild forms of influenza can sometimes occur without fever (afebrile form of influenza). Complications are associated with the addition of bacterial flora (pneumonia, frontal sinusitis, sinusitis, otitis media, sinusitis, toxic myocarditis).

Diagnostics. During an influenza epidemic, diagnosis is not difficult. In inter-epidemic times, this disease is rare and occurs in the form of mild and erased forms. In these cases, influenza is difficult to distinguish from acute respiratory infections of other etiologies. To confirm the diagnosis of influenza, the detection of the virus in the material from the pharynx and nose, as well as the detection of an increase in the titer of specific antibodies in the study of paired sera, is used: the first serum is taken before the 6th day of the disease, the second after 10-14 days. Diagnostic is the increase in antibody titers by 4 times or more.

Treatment. Patients with influenza are treated at home. Patients with severe forms of influenza, with complications and severe concomitant diseases, as well as for epidemiological indications (from hostels, boarding schools, etc.) are sent for inpatient treatment. Those being treated at home are placed in a separate room or isolated from others using a screen. For them, separate dishes are allocated, which are disinfected with boiling water. Persons caring for the patient should wear a four-layer gauze mask and change it every 4 hours. During the febrile period, the patient is recommended to rest in bed and drink plenty of alkaline fluids.

To prevent complications, especially for older people with high blood pressure, it is necessary to include in the diet green tea, chokeberry jam or juice, citrus fruits, as well as P vitamins (rutin) in combination with 500 mg of ascorbic acid per day. An effective remedy is anti-influenza donor gamma globulin, which is used for severe forms of influenza in the earliest stages (adults 6 ml, children 0,15-0,2 ml/kg). You can use normal human immunoglobulin, which is administered intramuscularly in the same doses. Antibacterial therapy is indicated only for complications. Synthetic penicillins and broad-spectrum drugs are most often used. Pathogenetic and symptomatic drugs are widely used. To reduce headaches and muscle pain, analgesics and others are used. Antihistamines (pipolfen, suprastin, diphenhydramine) have a therapeutic effect to relieve sensitization. To improve the drainage function of the bronchi, alkaline inhalations, expectorants and bronchodilators are used.

For symptoms of rhinitis, naphthyzin, galazolin, sanorin, etc. are used topically. Cupping and mustard plasters are prescribed for convalescents. In extremely severe, hypertoxic forms of influenza (with a temperature above 40 °C, shortness of breath, cyanosis, severe tachycardia, decreased blood pressure), patients are treated in intensive care wards with detoxification therapy. These patients are injected intramuscularly with anti-influenza immunoglobulin (6-12 ml), and broad-spectrum antibiotics are prescribed (oxacillin, methicillin, ceporin 1 g 4 times a day). A mixture containing 2-200 ml of hemodez or 300% glucose solution, 40-0,25 ml of 0,5% strophanthin solution, 0,05 ml of 2% Lasix solution is administered 1 times a day intravenously. 250-300 mg of prednisolone, 10 ml of 2,4% aminophylline solution, 10 ml of 5% ascorbic acid solution, 10 ml of 10% calcium chloride solution, 400 ml of rheopolyglucin, 10-000 units of contrical. If breathing becomes more frequent (more than 20 respiratory movements per minute), or breathing rhythm disturbances occur, the patient is transferred to artificial ventilation.

Forecast. With influenza without complications, the ability to work is restored after 7-10 days, with the addition of complications - not earlier than 3-4 weeks. The prognosis for life is favorable, severe forms with encephalopathy or pulmonary edema are extremely rare, while patients (usually during epidemics) are hospitalized.

Prevention of influenza is carried out using specific vaccine prophylaxis. Vaccination with live (intranasal) or inactivated (intradermal and subcutaneous) vaccines is used. Vaccination should precede the onset of an influenza epidemic, since vaccines are created based on the circulating influenza viruses in a given season. Special vaccines are used for children of different age groups, adults and the elderly. Sometimes the reaction to the vaccine occurs in the form of short-term malaise and low-grade fever. It is much milder than the disease, and you should not be afraid of it. The formation of immunity occurs only against influenza, so a child who has been vaccinated may well become ill with another viral disease. All people sick with the flu should be isolated from healthy people, the room where the patient is located should be ventilated, and wet cleaning should be carried out regularly. Anyone who is in contact with a person with the flu is recommended to instill interferon into the nose for a week; you can give aflubin, ascorbic acid or dibazole. Adults are recommended to take rimantadine in appropriate dosages. Children over 1 year of age can be prescribed Algirem. To prevent influenza A, you can use rimantadine, which is given throughout the epidemic outbreak. Current and final disinfection is carried out in the fireplace (dishes are doused with boiling water, laundry is boiled). Isolate the patient from others, allocate individual dishes, which should be scalded with boiling water.

3. Parainfluenza

Parainfluenza is a disease of the respiratory tract, characterized by moderate intoxication with a primary lesion of the mucous membranes of the nose and larynx.

Etiology. Viruses belong to the paramyxovirus family. They are distinguished from influenza viruses by the stability of the antigenic structure and the absence of visible variability in the virion genome.

Epidemiology. The highest incidence is recorded in children of the first 2 years of life, which can be explained by the narrow lumen of the larynx, looseness of the submucosal layer in the subglottic space, children over 7 years of age rarely get parainfluenza. The factors predisposing to the development of croup syndrome include lymphatic-hypoplastic diathesis. The source of infection is a sick person who is dangerous during the entire period of illness (up to 10 days). The route of transmission is airborne. The incubation period is from 2 to 7 days.

Pathogenesis. The entrance gates of infection are the mucous membranes of the nose, pharynx, larynx, where inflammatory changes occur. The virus reproduces in the epithelial cells of the respiratory tract, destroying the cells. Viruses and decay products of epithelial cells partially penetrate the bloodstream, which contributes to the development of fever and intoxication.

Clinic. The disease begins gradually with an increase in body temperature to 38 ° C, the appearance of hoarseness, and persistent cough, which occurs with the development of laryngeal stenosis. Stenosing laryngotracheitis is manifested by a triad of symptoms: a rough, “barking” cough, noisy stenotic breathing, and a hoarse voice. Croup syndrome can occur with all acute respiratory viral infections. It occurs due to swelling and inflammatory changes in the airways, preglottic space and vocal cords, which leads to a narrowing of the lumen of the larynx. Laryngeal stenosis develops acutely, usually at night. The child wakes up with a rough “barking” cough, noisy breathing, and becomes restless and frightened. There are four degrees of laryngeal stenosis. I degree laryngeal stenosis is manifested by a rough, “barking” cough, hoarseness, and inspiratory shortness of breath during physical exertion. II degree laryngeal stenosis is manifested by pallor of the skin, perioral cyanosis, and tachycardia. Children are restless, excited, noisy breathing with retraction of the jugular fossa and auxiliary respiratory muscles, a rough, “barking” cough, a hoarse voice. III degree laryngeal stenosis is manifested by respiratory failure, cyanosis of the lips, acrocyanosis, pallor of the skin, and sweating. Breathing is noisy with a sharp retraction of the compliant areas of the chest.

Children are restless, rush about, feel a sense of fear. Heart sounds are muffled, tachycardia. Stenosis of the larynx of the IV degree (asphyxia) is manifested by the serious condition of the patient, the skin is pale gray, cyanotic, the extremities are cold. Breathing is frequent, shallow, periodically with deep breaths, apnea, bradycardia. Consciousness is absent, death from asphyxia may occur.

Treatment. Etiotropic therapy, sedative therapy, hormonal therapy, desensitizing therapy, infusion therapy, symptomatic therapy. Inhalation, physiotherapy. Nasotracheal intubation is possible.

Author: Gavrilova N.V.

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