Respiratory syncytial virus is a disease of viral etiology characterized by inflammation of the lower respiratory tract, moderate catarrhal and intoxication syndrome. Clinical manifestations include subfebrile fever, cognition, weakness, persistent dry, paroxysmal cough, expiratory dyspnea. The diagnosis is confirmed by isolating the virus from nasopharyngeal flushes and serological diagnostics. Treatment is usually outpatient, with interferon preparations, expectorants and mucolytic agents.
Respiratory syncytial virus (RSV) is an ARI that occurs with a predominant lesion of the lower respiratory tract in the form of bronchitis, bronchiolitis and interstitial pneumonia. The name of the disease reflects the place of reproduction of the virus in the body (respiratory tract) and cytopathogenic effects caused in cell culture by the formation of extensive syncytial fields (cell fusion). In the structure of various acute respiratory infections, respiratory syncytial virus accounts for 15-20% of all cases. Children of the first year of life and early age are most vulnerable to infection. In this regard, special attention is paid to respiratory syncytial virus by pediatrics.
Respiratory syncytial virus belongs to the genus Pneumovirus, family Paramyxoviridae. Virions have a rounded or filamentous shape, a diameter of 120-200 nm, a lipoprotein shell. A distinctive feature of the RSV is the absence of hemagglutinin and neuraminidase in the shell. In the external environment, the virus is quickly inactivated by heating and using disinfectants, but it tolerates low temperatures well and can persist for up to several hours in droplets of mucus.
Disease refers to viral diseases with airborne transmission. The virus can be spread by both sick people and its carriers. Respiratory syncytial virus is characterized by family and collective outbreaks; cases of nosocomial infection are recorded, especially in pediatric hospitals. The prevalence of infection is widespread and year-round with outbreaks of morbidity in winter and spring. The greatest susceptibility to respiratory syncytial virus is observed among premature infants, children aged 4-5 months to 3 years. As a rule, at an early age, most of the children are ill with respiratory syncytial virus. Due to the instability of acquired immunity, repeated cases of RSV are not uncommon, which, against the background of residual immunity, proceeds in a more erased form. However, with the complete disappearance of specific secretory antibodies (IgA) from the body, a manifest form of respiratory syncytial virus may develop again.
The pathogenesis of RSV is similar to the mechanism of development of influenza and parainfluenza and is associated with the tropicity of viruses to the epithelium of the respiratory tract. The respiratory tract serves as the entrance gate; the primary reproduction of the virus occurs in the cytoplasm of the epithelial cells of the nasopharynx, however, the pathological process can quickly spread to small bronchi and bronchioles. At the same time, hyperplasia of the affected cells occurs, the formation of pseudo-giant cells and symplasts. Cellular changes are accompanied by the phenomena of hypersecretion, narrowing of the lumen of the bronchioles and their blockage by thick mucus, leukocytes, lymphocytes and exfoliated epithelium. This leads to a violation of the drainage function of the bronchi, the formation of small-focal atelectasis, emphysema of the lung tissue, violation of gas exchange. The further development of respiratory syncytial virus is determined by the degree of respiratory failure and the addition of bacterial flora.
Depending on the predominant interest of certain departments of the respiratory tract, RSV can occur in the form of nasopharyngitis, bronchitis, bronchiolitis or pneumonia. Usually, the first symptoms of respiratory syncytial virus appear 3-7 days after infection. The development of the disease is gradual: in the first days, subfebrility, cognition, moderate headache, scanty serous-mucous discharge from the nose are bothering. In some cases, there are signs of conjunctivitis, injection of sclera vessels. A characteristic symptom of respiratory syncytial virus is persistent dry cough.
In the case of pneumonia, the temperature rises to 38-39 ° C, intoxication phenomena increase. There is tachypnea, pain behind the sternum, sometimes – attacks of suffocation. The cough becomes productive, paroxysmal with the separation of thick, viscous sputum at the end of the attack. With a severe form of respiratory syncytial virus, signs of respiratory failure increase, expiratory dyspnea occurs, lip cyanosis and acrocyanosis develop. In some cases, RSV occurs with the phenomena of obstructive bronchitis and false croup. The duration of the course of mild forms of RSV is a week, medium-severe – 2-3 weeks. Of the overlapping bacterial complications, otitis media, sinusitis, and pneumonia most often occur.
The most severe RSV occurs in children of the first year of life. At the same time, there is a high fever, agitation, convulsive syndrome, persistent cough, vomiting, mushy or loose stools. Deaths are recorded in 0.5% of cases.
Diagnosis and treatment
The basis for the alleged diagnosis of “respiratory syncytial virus” can be a characteristic clinical picture, a tense epidemiological situation and a massive outbreak of the disease, especially among children. The lung radiograph reveals a decrease in the transparency of the pulmonary fields, an increase and heaviness of the bronchovascular pattern, small focal inflammatory shadows, areas of atelectasis and emphysema. Specific laboratory confirmation of respiratory syncytial virus is carried out by isolating the RSV from the nasopharynx on tissue culture and determining the increase in antibody titer in paired sera (NR, IFT and RPH). During differential diagnosis, influenza, parainfluenza, rhinovirus infection, adenovirus infection, legionellosis, ornithosis, whooping cough, mycoplasma, chlamydia and bacterial pneumonia are excluded.
Treatment of mild and moderate cases of RSV is carried out on an outpatient basis; children of the first year of life and patients with a complicated course of the disease need hospitalization. In the acute period, bed rest, a full-fledged sparing diet, oxygen therapy, alkaline inhalations are indicated. Antiviral drugs are prescribed (acridonacetic acid, umifenovir, kagocel), expectorants and bronchodilators, in the presence of obstructive syndrome – glucocorticoids. With the development of bacterial complications, antibiotics are prescribed.
Prognosis and prevention
In most cases, the prognosis is favorable; about 2% of patients need hospitalization. Fatal outcomes are possible among premature infants and newborns, children with congenital heart defects, lungs, and immunodeficiency. Bronchiolitis suffered in early childhood, associated with respiratory syncytial virus, is a risk factor for the development of bronchial asthma in children in the future.
Preventive measures are aimed at preventing nosocomial and collective outbreaks of RSV by isolating patients, disinfection and frequent ventilation of premises. A vaccine against respiratory syncytial virus is under development; immunoglobulin against the RSV can be used as a measure of specific immunoprophylaxis.