Parapertussis is an acute respiratory tract infection caused by Bordetella parapertussis. Clinically resembles a mild form of whooping cough, manifested by rhinitis, pharyngitis, paroxysmal cough (sometimes with reprises), subfebrility. Etiological diagnosis is performed by the cultural method, using PCR analysis and serological tests (RPH, ELISA). Paracoccus therapy is carried out by symptomatic means: expectorants, antihistamines, bronchodilators. Immunoprophylaxis is not carried out.
ICD 10
A37.1 Whooping cough caused by Bordetella parapertussis
General information
Parapertussis is a respiratory infection mainly of childhood caused by parapertussis bacillus. The incidence is on average 1:100,000 of the child population, but only about a third of paracoccus episodes are verified in the laboratory. The remaining cases either remain undiagnosed, or are mistaken for whooping cough. The age structure is dominated by children from 3 to 7 years old who attend organized collectives. Children who have had whooping cough or vaccinated are not protected from paracoccus disease.
Causes
Characteristics of the pathogen
The infectious pathogen ‒ Bordetella parapertussis ‒ was discovered and studied in 1937 by American bacteriologists G. Eldering and P. Kendrick. According to its morphological features and cultural properties, bordetella paracoclusha is similar to the whooping cough bacillus Borde-Zhangu. Their main difference lies in the inability of B. parapertussis to produce pertussis exotoxin, which is the main factor in the pathogenicity of B. pertussis. In addition, Paracoccus bacteria are capable of forming urease and tyrosinase enzymes.
Bordetella parapertussis is not stable in the external environment: high and low temperatures, ultraviolet light, direct sunlight, disinfectant solutions, drying are harmful to bacteria. At the same time, bordetelles are practically not susceptible to antibacterial drugs.
Epidemiology
The source and distributor of B. parapertussis is a person with paracoccus or a bordetell carrier. Transmission of infection is carried out by airborne droplets. Characterized by high susceptibility to paracoccus, especially in preschool age. The contagiousness index is about 40%. Children of the first year of life rarely get sick.
Epidemic outbreaks are characteristic of the autumn-winter months, their frequency does not coincide with whooping cough. The duration of specific immunity after paracocclusion has not been established. There is partial cross-immunity between both infections.
Pathogenesis
Once in the respiratory tract, B. parapertussis colonizes the epithelium of the larynx, trachea, bronchial tree, and pulmonary alveoli. There is a multiplication of bordetella, which secrete pathogenicity factors: filamentous hemagglutinin, pertactin, tracheal cytotoxin, enzymes (urease, hyaluronidase, lecithinase, plasmocoagulase, adenylate cyclase, etc.).
Catarrhal inflammation develops in the respiratory tract, the production of bronchial secretions increases, focal necrosis of the mucous membrane forms. Under the influence of bacterial toxins that irritate the respiratory tract receptors, convulsive cough develops. Inflammatory and dystrophic changes in the mucous membrane of the respiratory tract in parapertussis are less pronounced than in whooping cough, therefore all clinical symptoms are less prolonged and less pronounced.
Classification
Depending on the frequency and severity of convulsive cough, mild and moderate forms of paracoccus are distinguished. According to the clinical picture, there is a typical and atypical course:
- the typical course is accompanied by whooping cough-like attacks;
- atypical course suggests erased symptoms, the disease is detected only by serological markers. Also, the subclinical forms include transient bacteriocarriage.
Symptoms
The incubation (latent period) lasts from 4-7 days to 2 weeks. In the clinical course of parapertussis, there are periods: catarrhal, spasmodic cough and resolution of the disease, but they are less pronounced than in the case of whooping cough.
Catarrhal phenomena are represented by nasal congestion, pharyngeal hyperemia, and sore throat. An increase in body temperature to subfebrile figures is observed in a small number of patients. Well-being is slightly disturbed. After 3-5 days, the catarrhal period is replaced by the appearance of a tracheobronchial cough.
Depending on the severity of coughing attacks, there are erased and whooping cough-like forms of parapertussis. Whooping cough-like variant occurs in about 16% of patients. Its course is characterized by seizures of convulsive cough, which are accompanied by reprises, hyperemia and puffiness of the face, the discharge of viscous sputum, often end in vomiting. Cough paroxysms occur less frequently (up to 5-7 times a day) and last less than with whooping cough. This is especially true for children vaccinated with DPT.
The period of convulsive cough lasts 2-3 weeks. In the resolution phase, the seizures are reduced, the cough weakens and disappears altogether. With the erased form, which accounts for the majority of cases of paracocclusion (84%), the cough is less intrusive, resembles an acute bronchitis clinic. The disease occurs in mild and moderate form, severe and complicated course is usually not observed.
Complications
In some cases (in children with a burdened premorbid background), it is possible to attach a bacterial infection or concomitant ARVI with the development of pneumonia, bronchitis. Typical complications of paracocclusion are nosebleeds, conjunctival hemorrhages. With severe attacks of spasmodic cough, characteristic of simultaneous coinfection with pathogens of whooping cough and parapertussis, convulsions, umbilical and inguinal hernias, pneumothorax, subcutaneous emphysema may occur. When the bronchi are blocked with viscous mucus, atelectasis and emphysema of the lungs develop.
Diagnostics
When contacting a pediatric infectious disease specialist, complaints are made about periodic paroxysmal cough. In the anamnesis, it is often possible to trace contact with a patient with paracoccus. The general condition of the child is satisfactory, the temperature is more often normal, sometimes dry wheezing in the lungs is heard. However, it is impossible to diagnose paracoccus on the basis of clinical data and epidanamnesis alone. A decisive role is played by laboratory studies aimed at detecting B. parapertussis or antibodies to the pathogen:
- Bacteriological examination. Perform the sowing of mucus on nutrient media. The sampling of the material can be carried out by the method of a cough push or a posterior pharyngeal swab. The tank examination must be carried out twice.
- Molecular genetic diagnostics. PCR allows you to identify the DNA of the causative agent of paracoccus already in the catarrhal period of the disease. Smear samples from the oropharynx and nasopharynx are examined.
- Serological reactions. RPH, IFT, ELISA. The ELISA qualitatively determines the presence of specific IgM and IgG immunoglobulins to the paracoccus bordetella. RPH with pertussis and parapertussis diagnoses reveal increased antibody titers (1:80 and higher) to the parapertussis antigen and their increase in dynamics.
- Auxiliary diagnostics. Unlike whooping cough, leukocytosis is usually not noted or expressed moderately in a clinical blood test, lymphocytosis is short-term. Lung x-ray reveals an expansion of the roots, an increase in the pulmonary pattern, and sometimes a compaction of the lung tissue.
Differential diagnosis
Whooping cough-like attacks can occur with various respiratory infections, allergies. First of all, parapertussis is differentiated with a mild form of whooping cough. Also excluded are:
- ARI: adenovirus infection, MS infection;
- respiratory mycoplasmosis and chlamydia;
- laryngotracheitis;
- tracheobronchitis;
- bronchial asthma;
- foreign bodies of the respiratory tract;
- bronchial stricture;
- tuberculous bronchoadenitis.
Treatment
Hospitalization is rarely required, usually with a complicated course, mixed infection. Regime moments include limiting physical and psycho-emotional loads that provoke coughing paroxysms, mandatory walks, frequent airing of premises. Nutrition should be fortified, easily digestible, food should be given to the child in small portions, preferably after a cough attack.
Treatment of paracoccus is exclusively symptomatic. For better discharge of viscous sputum, mucolytics, bronchodilators, inhalations with expectorant drugs are used. Antihistamines are indicated for desensitization. In a hospital setting, oxygen therapy sessions can be prescribed. Antibiotics are not used for paracoccus.
Prognosis and prevention
Parapertussis in most cases proceeds easily and resolves within 2-3 weeks. Complications develop extremely rarely and do not have fatal consequences. A severe course is possible with concomitant chronic diseases, simultaneous infection with B. pertussis and B. parapertussis, and the addition of a secondary infection.
Patients are isolated from others for 25 days from the onset of the disease. Bacilli carriers are quarantined for up to two negative bacilli. Specific immunization is not carried out. Vaccination reduces the severity of the course of paracoccus.
