What is Whooping Cough?
Whooping cough is an infectious disease of the respiratory tract, which is caused by the specific bacteria Bordetella pertussis (Bordet-Jangu wand), characterized by acute catarrh of the respiratory tract and spasmodic cough attacks.
Causes of Whooping Cough
The causative agent of pertussis (Bordetella pertussis) is a short stick with rounded ends (0.2-1.2 μm), gram-negative, fixed, well-colored with aniline dyes. Antigenically heterogeneous. The antigen, which causes the formation of agglutinins (agglutinogen), consists of several components. They are called factors and are designated by numbers from 1 to 14. Factor 7 is generic, factor 1 contains B. pertussis, 14 – 5. parapertussis, the rest are found in different combinations; for pertussis pathogen, these are factors 2, 3, 4, 5, 6, for para-pertussis – 8, 9, 10. Agglutination reaction with adsorbed factor sera allows differentiation of bordetella species and determine their antigenic variants. The causative agents of whooping cough and paracoccus are very unstable in the external environment, so sowing should be done immediately after taking the material. Bacteria quickly die during drying, ultraviolet radiation, under the influence of disinfectants. Sensitive to erythromycin, chloramphenicol, antibiotics of the tetracycline group, streptomycin.
Epidemiology of whooping cough
Whooping cough is widespread in the world. About 60 million people fall ill each year, of which about 600,000 die. Whooping cough is also found in countries where pertussis vaccinations have been widely carried out for many years. So, in the United States from 1980 to 1989. 27,826 cases of whooping cough were registered, 12% of them were persons 15 years and older [P. Lange, 1993]. Probably, among adults, whooping cough is more common, but it is not detected, as it proceeds without characteristic convulsive seizures. When examining individuals with persistent long cough, 20-26% of serologically pertussis infection is detected. The reservoir and source of infection is only human (patients with typical and atypical forms of whooping cough, as well as healthy bacteria carriers). Especially dangerous are patients in the initial stage of the disease (catarrhal period). Transmission of infection by airborne droplets. Upon contact with patients in susceptible people, the disease develops with a frequency of up to 90%. More often ill children of preschool age. More than 50% of cases of pertussis in young children are associated with maternal immunity deficiency and possibly the absence of transplacental transmission of protective specific antibodies. In countries where the number of vaccinated children is reduced to 30% and below, the level and dynamics of the incidence of whooping cough becomes what it was in the pre-vaccination period. Seasonality is not very pronounced, there is a slight increase in the incidence in autumn and winter.
Pathogenesis during the Whooping Cough
The gateway to the infection is the mucosa of the respiratory tract. Pertussis microbes attach to cells of the ciliated epithelium, where they multiply on the surface of the mucous membrane, without penetrating the bloodstream. An inflammatory process develops at the site of pathogen introduction, the activity of the ciliary apparatus of epithelium cells is inhibited and secretion of mucus increases. Further, ulceration of the airway epithelium and focal necrosis occur. The pathological process is most pronounced in the bronchi and bronchioles, less pronounced changes develop in the trachea, larynx and nasopharynx. Muco-purulent corks clog the lumen of the small bronchi, focal atelectasis, emphysema develops. Peribronchial infiltration is observed. In the genesis of convulsive seizures, it is important to sensitize the organism to pertussis toxins. Constant irritation of the respiratory tract receptors causes coughing and leads to the formation of a dominant-type excitation focus in the respiratory center. As a result, typical attacks of spasmodic cough can also be caused by non-specific irritants. From the dominant focus, arousal may radiate to other parts of the nervous system, such as the vasomotor (increase in blood pressure, vasospasm). Irradiation of excitation also explains the appearance of convulsive contractions of the muscles of the face and body, vomiting, and other symptoms of whooping cough. The transferred pertussis (as well as the pertussis vaccinations) does not provide intense lifelong immunity, therefore repeated diseases of whooping cough are possible (about 5% of cases of pertussis occur in adults).
Congenital immunity due to maternal antibodies does not develop. The probability of infection by contact is 90%. Very dangerous for children under 2 years old.
The period of contagion lasts from one week to the appearance of cough and 3 weeks after. Since before the appearance of a characteristic cough, it is difficult to distinguish whooping cough from other infections, within one week the infected people manage to infect their surroundings.
The toxin secreted by pertussis acts directly on the central nervous system, irritates the neural receptors of the respiratory mucosa and activates the cough reflex, resulting in characteristic attacks of convulsive cough. If neighboring nerve centers are involved in the process, vomiting occurs (characteristic of the termination of a cough attack), vascular disorders (a drop in blood pressure, vascular spasm), and nervous disorders (convulsions).
Whooping Cough Symptoms
The incubation period lasts from 2 to 14 days (usually 5-7 days). The catarrhal period is characterized by general malaise, slight cough, runny nose, low-grade fever. Gradually, the cough increases, children become irritable, capricious. At the end of the 2nd week of illness, a period of spasmodic cough begins. Attacks of convulsive cough begin suddenly, manifest as a series of cough tremors, followed by a deep whistling breath – a reprise, followed by a series of short convulsive pushes again. The number of such cycles during an attack ranges from 2 to 15. The attack ends with the discharge of viscous vitreous sputum, sometimes vomiting is noted at the end of the attack. During an attack, the child is agitated, the face becomes bluish in color, the neck veins are dilated, the eyes are filled with blood, the tongue protrudes from the mouth, the frenulum of the tongue is often injured, and respiratory arrest can occur with the development of asphyxiation. In young children, the reprise is not pronounced. Depending on the severity of the disease, the number of attacks can vary from 5 to 50 per day.
The duration of attacks on average is 4 minutes.
The period of convulsive cough lasts for 3-4 weeks, then the attacks become less frequent and finally disappear, although the “usual” cough continues for another 2-3 weeks (the resolution period). In adults, the disease proceeds without attacks of convulsive cough, manifested by prolonged bronchitis with persistent cough. Body temperature remains normal. Overall health is satisfactory. Worn out forms of whooping cough can be observed in children who have been vaccinated.
The most common complication is pneumonia due to pertussis or a secondary bacterial infection. Other complications include acute laryngitis (inflammation of the larynx) with laryngeal stenosis (false croup), bronchiolitis, nosebleeds, respiratory arrest, umbilical, inguinal hernia. Encephalopathy may also occur – a non-inflammatory change in the brain that, as a result of seizures, can lead to death or leave permanent damage behind: deafness or epileptic seizures.
In adults, complications are rare.
Diagnosis of Whooping Cough
A reliable diagnosis in the catarrhal period can be made after obtaining the results of bacteriological tests. The basis for the study in these cases usually serve as epidemiological data (contact with patients with whooping cough, lack of data on vaccinations, etc.). In the period of spasmodic cough, whooping cough is much easier to diagnose as there are typical attacks. However, it should be borne in mind that sometimes coughing attacks similar to pertussis may be due to other causes (adenovirus infection, viral pneumonia, airway pressure in malignant tumors, infectious mononucleosis, etc.), on the other hand, whooping cough can occur atypically without characteristic attacks (in vaccinated children, in adults). The main method of laboratory confirmation of diagnosis is the isolation of the causative agent of whooping cough. The frequency of release depends on the timing of taking the material; on the 1st week of the disease, positive results can be obtained in 95% of patients, on the 4th – only in 50%, and starting from the 5th week, the microbe cannot be isolated. Material from the nasopharynx take a dry swab with immediate seeding on the cups with a selective nutrient medium. The method of “cough plates” is also used, in which the Petri dish with the nutrient medium is placed in front of the mouth of the coughing child (about 10 cm apart), held in this position for a few seconds to catch 5-6 cough shocks. The seeding cup is quickly closed with a lid and placed in a thermostat. During transportation, they protect them from cooling (they are wrapped in paper, cotton wool, a heating pad filled with hot water is placed in a container). However, the cough lamella method is significantly inferior in terms of the frequency of isolating pertussis pathogens and swabbing. Serological methods can be used for retrospective diagnosis, as well as in patients with negative bacteriological findings. From the old methods you can use RSK, RPGA, agglutination reaction. Diagnostic is the increase in antibody titers 4 times or more, as well as high antibody titers (1:80 and above).
Recently, an enzyme immunoassay method has been successfully used to detect antibodies in serum (class M immunoglobulins) and in nasopharyngeal mucus (class A immunoglobulins). These antibodies appear from the 2-3rd week of the disease and persist for 3 months. Differentiated in the catarrhal period of the disease from acute respiratory infections, in the period of spasmodic cough from other diseases, accompanied by persistent cough at normal body temperature and the absence of signs of general intoxication.
Whooping Cough Treatment
Treatment of patients is carried out only in the hospital. Special conditions are provided for patients – the room should be well ventilated, the air should be moistened with special humidifiers, air conditioners or wet towels. Severely ill infants are advised to be placed in a darkened, quiet room and as disturbed as possible, since exposure to external stimuli can cause a severe coughing fit. For older children with mild forms of the disease, bed rest is not required. It is recommended that the patient stay in the open air, children outside practically do not cough.
Serious attention should be paid to nutrition, food is recommended to give often, but in small portions. With frequent severe vomiting, intravenous fluids must be injected. For infants, the extraction of mucus from the pharynx is vital. Of great importance for whooping cough, especially in young children, with pronounced hypoxia, there is widespread use of oxygen therapy (content in an oxygen tent).
Antibiotics are used at an early age, and in severe and complicated forms. During the catarrhal stage, the drug of choice is erythromycin.
It is recommended to use specific pertussis gammaglobulin, which is administered intramuscularly in a dose of 3 ml daily for 3 days.
Antitussive and sedatives should be used carefully or not at all, because the effectiveness of expectorants and cough suppressants, as well as light sedatives is questionable. Impacts provoking coughing (mustard plasters, banks) should be avoided.
During respiratory arrest, it is necessary to clear the respiratory tract from mucus by sucking it out and perform artificial respiration.
Prevention of Whooping Cough
The only reliable means of specific prophylaxis is vaccination. Pertussis vaccine: pertussis-diphtheria-tetanus adsorbed liquid vaccine; Tetrakok; Tritanriks (vaccine for the prevention of whooping cough, diphtheria, tetanus and hepatitis B); Infanrix (Aacdc) (acellular vaccine for the prevention of whooping cough, diphtheria and tetanus).
All children from 3 months are given a course of pertussis vaccination, consisting of 3 injections of DPT vaccine with an interval of 1.5 months. Revaccination done in 1.5-2 years after the course of vaccination. Vaccination in 70-80% prevents disease or it proceeds in a mild form.
Children who have come into contact with the patient until the age of 7 who have not had whooping cough are subject to dissociation within 14 days since the last contact with the patient. All children who were in contact with the patient are subject to carrier screening.
Contact children under the age of 1 year and not vaccinated injected for the prevention of normal human immunoglobulin (measles) in 3 ml for 2 days in a row.