Pertussis - Causes, symptoms and treatment. MF.

Pertussis is an acute, anthropogenic bacterial infection, with an airborne droplet mechanism, and characterized by a long-lasting paroxysmal spasmodic cough.

This disease became known from 1578, when describing the epidemic outbreak in Paris. After that, only in 1906, the pathogen was isolated from the patient's sputum, and much later a vaccine was created, which reduced the risk of disease and eliminated epidemic outbreaks.

Causative agent of pertussis

The causative agent of pertussis is Bordetella pertusis( there are also pathogens that cause pertussis-like symptoms - Bordetella parapertusis and bronchiseptica).

Bordetella pertusis in the airway

The causative agent is shallow, with rounded edges, a rod that has structural features that predetermine the mechanism of development of the asymptoms of the disease:

• Filamentous hemagglutinin( surface protein, which formed the basis for the creation of the new Infanricks vaccine) - it is attached only tociliary epithelial airways, especially in the bronchi, less this process is expressed in the trachea / larynx / nasopharynx.

• In the body it forms a capsule - it provides protection against phagocytosis.

• Pertussis exotoxin is responsible for specific symptoms, by neurotoxic action( selectively affects cough receptors, like nerve endings located in the bronchi, also directly affects the cough / respiratory center in the medulla oblongata - a vicious circle of pathological cough is formed).
Also exotoxin forms histamine-sensitizing and lymphocytic-stimulating action.

• Tracheal cytotoxin is the "right arm" of pertussis toxin, because it helps it form this vicious circle of debilitating cough by damaging the ciliated epithelium of the respiratory tract - this leads to the cessation of ciliary movements and stagnation of the bronchial fluid, and at the site of the pathogen the hemorrhage and necrosis, in yoga, the cough receptors are even more irritated.

• Dermonecrotoxin possesses neurotropic, that is selective excites neurons in the medulla oblongata, but not only the cough center, but also the vasomotor, as a result of this, vascular disorders occur.

• Endotoxin is released only after the death of the pathogen and has a toxic-pyrogenic effect( this explains the general clinical symptoms of the catarrhal period).

• The causative agent produces urease, an enzyme that provides the decomposition of uric acid with ammonia( toxic) and carbon dioxide.

• The presence of pathogenicity enzymes ensures the penetration of the pathogen into the deep tissue of the respiratory department. These include: hyaluronidase - dissociates intercellular compounds, lecithinase - cleaves the phospholipid layer of the membrane, coagulase - provides plasma clotting.

• The ability to express the variability of pathogenic( malicious) properties, which leads to the formation of resistance to postvaccinal infection. But after the transfer of the disease, a stable, tense almost lifelong immunity is formed.

The causative agent is very sensitive to environmental factors: UVI, drying, the action of disinfectants, in the external environment is stable for several hours and volatile at a distance of 2.5 m.

Susceptibility is ubiquitous, without sexual and age restrictions. As such, there is no seasonality principle, because the pathogen circulates throughout the year, but like all respiratory infections, outbreaks are registered more often in the autumn-winter period. The possibility of the disease decreases with good intensity postvaccinal immunity and a low infectious dose of the pathogen. In recent decades, the incidence trend has been registered due to:

• variability of pathogenic properties( antigenic drift) to postvaccinal immunity;
• reduce the effectiveness of old vaccines;
• low level of grafting;
• Weakened post-vaccination immunity due to immunization defects.

Causes of pertussis infection

Source - sick person. The most dangerous with atypical and erased current, also those who are on the last days of the incubation period( including all other clinical stages) ≈ 25-30 days. The difficulty of preventing infection from the source is that the incubation period can not be noticed, and the catarrhal period in whooping cough is in mild form and does not pay attention to it, even when a cough occurs( because it begins gradually, with an increase).As a result, isolation often becomes late.

Pathways of infection - aerogenic( due to the air-drop mechanism of transmission with close and long-term contact).There were also recorded infections from domestic and wild animals, but not pertussis, and pertussis-like disease( Bordetella bronchiseptica).

Symptoms of whooping cough

The incubation period of lasts 3-14 days( usually 5-7), this period starts from the moment of introduction of the pathogen, to the first clinical manifestations. The pathogen penetrates through the upper respiratory tract and is attached to the ciliate epithelium. As the critical number of pathogens is reached, the next period begins - catarrhal. From the last days of this period, the patient is contagious.

The catarrhal period of lasts 10-14 days, does not differ in any features( ie ↑ t ° up to 39, runny nose, malaise).The only difference is the nature of the cough: it is dry, obtrusive, often begins by the evening or at night, is not facilitated by the reception of symptomatic means. Every day cough is getting stronger, due to the action of toxins - whooping cough and tracheal. Pertussis toxin, as mentioned above, forms a vicious circle - irritating the cough receptors of the bronchi, nerve fibers impulse into the cough center of the medulla oblongata, where the pathological focus of constant excitation is formed( also due to the direct action of the toxin on this center), then on the reverseThis focus gives impulses to the cough receptors of the bronchi( from which the impulses came from the beginning) - so the pathological foci that feed each other are formed. Moreover, the cough center in the medulla oblongata becomes excited to such an extent that it reacts to almost any stimulus( light, sound, emotional), causing a cough. The action of tracheal toxin is similar to that of pertussis, but only through mechanical stimulation - it causes congestion of the mucociliary fluid of the bronchi, which is also an irritant of the cough receptors( they are mechanical and pressure receptors), and then flows into this vicious circle.

The period of spasmodic cough lasts from 2-8 weeks or more. During this period, people become martyrs, because every attack of coughing is a struggle for inspiration. There is a bright specific symptomatology and a paroxysmal( epileptic) cough comes to the fore, preceded by a peculiar aura of perspiration and tickling in the throat( or sneezing), followed by coughing attacks: coughing thrusts one after another without the possibility of inspiration. The cough is "barking", dry, with very thick and hard-to-defecate sputum( in consistency as a construction selectone).In such periods, babies may have apneas( stopping breathing).

Cough occurs in the evening / night time and is not stopped by conventional protichashlevye means. As soon as it is possible to inhale, the air whistles through the spasmodic vocal chink, which explains the formation of "wheezing" or "reprise."

During this period, there are also changes in the cardiovascular system, but not only because of the violation of compensatory abilities, but also because of the direct influence of dermonecrotoxin on the vasomotor center, resulting in the following manifestations: vasospasm, increased arterial and venous pressure,violation of vascular permeability - as a consequence, pallor of the skin, acrocyanosis( cyanosis of the nasolabial triangle), hemorrhagic skin manifestations and injected sclera. As a consequence of the foregoing, the burden on the heart is increasing, which can lead to complications, especially if it is compromised.

Because of frequent and prolonged oxygen starvations, hypoxia( ↓ oxygen level in the blood) arises and the central nervous system suffers: encephalopathy, manifested by general anxiety, hypodynamia, sleep disturbance, convulsive readiness.

The recovery period of lasts for 3 weeks( it may take up to 6 months).Characterized by a gradual decline in cough( it is no longer so painful and paroxysmal).But even after recovery, the pathologically dominant focus in the cough center of the medulla oblongata leaves its changes( the threshold of sensitivity decreases) and, in the most common respiratory diseases, cough still acquires a pertussis-like shade.

There are flow characteristics in which the symptoms do not meet the standards:

• Atypical form of the disease( clinic erased and there is no consecutive change of periods)
• Features of the flow in young children: the presence of moderate and severe forms, in which symptoms are much brighter + instead of coughing appearsits equivalent in the form of sneezing, hiccups or screams + in children 1 year of age, the loss of acquired skills, especially motor and speech, is more likely to affect the CNS and convulsive readiness is formed. In the presence of a cough, a small wound is formed on the tongue bridle as a result of frequent irritation with coughing.
• Vaccinated persons may have a recurrence, but it occurs in mild or atypical form.
• Features of the modern course of the disease - often occurs as a mixed infection, ie in combination with other viral or bacterial pathogens.

Diagnosis of whooping cough

1. Objective evaluation is possible in the catarrhal and convulsive period, when assessing the nature of the cough.
2. UAC: ↑ Lc and LF, ESR ↑ or OK
3. On the roentgenogram: increase in the transparency of the lung tissue, low standing and flattening of the dome of the diaphragm, expansion of the pulmonary roots, the presence of share or segmental atelectasis.
4. Laboratory diagnostics:
- Bacteriological method( excretion of pathogens in the test material - sputum or mucus from the upper respiratory tract).Getting negative results, if there is a corresponding clinical symptomatology, does not give the right to exclude a diagnosis!
- The serological method is directed to the determination of antibodies by the formulation of RA( agglutination reaction) and RNGA( indirect hemagglutination reaction) - the method of paired sera is used and the antibody titer is observed to increase.

Treatment of whooping cough

1. Etiotropic therapy is aimed at destroying the pathogen. With this disease, antibiotics directed against a particular causative agent of pertussis( sumamed) are prescribed, but before the bacteriological results are obtained, it is possible to prescribe broad-spectrum drugs, with the subsequent change to the required ones. Etiotropic therapy is prescribed throughout the catarrhal period, an average of 2 weeks.

2. Pathogenetic and symptomatic:
- for arresting bronchospasm and bronchial obstruction, prescribing eufillin, as well as inhalations with berodual and berotek
- drugs that depress the cough reflex( children under 3 years old - neocodion, encoding, 3 years old - stoptussin, sinecode,tusuprex)
- mucolytic agents improving sputum evacuation - inhalation with ambroxol and bromhexine preparations
- preparations for hemodynamics and metabolic processes recovery in CNS - piracetam
- immune preparations: immunomodulators andimmunostimulants
- drugs of metabolic rehabilitation, replenish the reserve capacity of the body - vitamin complexes

For more severe clinical manifestations of patients hospitalized, in the hospital to the treatment are added: oxygen therapy, glucocorticoids, it is possible to use anti-pertussis antitoxic immunoglobulin human.

Complications of whooping cough

- On the part of the respiratory tract( respiratory tract): emphysema, atelectasis, bronchitis, pneumonia
- Heart and blood vessels: hemorrhages, myocardial dystrophy, carditis
- CNS: encephalopathies, cerebral edema
- ENT organs: otitis and rupture of drummembranes

Prevention of whooping cough

1. Isolation of patients: up to 7 years - for 25 days, older than 7 years - until the cessation of acute manifestations. After the recovery of the vaccination, if they coincide with the calendar vaccination rates, they are postponed for 1 month or 2 months for the development of complications. For all contact persons, medical surveillance is established within 14 days, with a 2-fold bacteriological study.
2. Vaccination is carried out at 3 months → at 4.5 months → 6 months → 18 months( in accordance with the national calendar of vaccinations).The following vaccinations are used: DTP( domestic), Tetracoccus( French), Infanrix( last and most reliable).

Therapist doctor Shabanova I.Е.