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What causes catarrhal-respiratory syndrome?
Medical expert of the article
Last reviewed: 04.07.2025
Diseases accompanied by catarrhal-respiratory syndrome are classified as acute respiratory diseases (ARD). Most often, they are caused by viruses (ARVI), less often - bacteria. The causes of catarrhal-respiratory syndrome are the action of allergenic (in vasomotor rhinitis, hay fever) and irritating substances (for example, chlorine), the cold factor. Often, the combined action of various factors is expressed (for example, the cold factor and viruses. viruses and bacteria).
The main causative agents of acute respiratory infections are viruses that have a high affinity for certain parts of the respiratory tract.
The total number of viruses (including their serotypes) that cause acute respiratory viral infections is more than 200. They are the cause of more than 90% of cases of acute respiratory infections.
The respiratory group includes influenza and parainfluenza viruses, adenoviruses, rhinoviruses, coronaviruses, and enteroviruses. Almost all of them cause diseases with a similar clinical picture - catarrhal-respiratory syndrome against the background of pronounced symptoms of intoxication. The clinical manifestations of these diseases are due to both the properties of the virus and the body's immunoreactivity.
The most clinically significant acute respiratory viral infections are: influenza, parainfluenza, diseases caused by respiratory syncytial, adeno- and rhinoviruses, as well as coronaviruses.
The similarity of the clinical picture is determined by common pathogenetic mechanisms in the development of ARVI:
- the introduction of the pathogen into the cells of the respiratory tract epithelium and its reproduction;
- viremia with the development of toxicosis and toxic-allergic reactions;
- development of an inflammatory process in the respiratory system;
- reverse development of the infectious process, formation of immunity.
The nature of the course of the infectious process is determined by a complex system of protective and adaptive reactions of the macroorganism, aimed at limiting the reproduction of viruses and their elimination.
At the initial stage of the disease, the leading role belongs to non-specific defense factors, local IgA and phagocytosis, and specific cellular and humoral immunity - in the recovery process.
Since the entry point for ARVI is the mucous membrane of the respiratory tract, local defense factors play a major role in preventing the development of the disease, among which macrophages and secretory immunoglobulins (primarily IgA, which can prevent pathogen adhesion to the surface of epithelial cells and mediate the destruction and elimination of viruses) dominate. When mucosal immunity is impaired, viruses primarily affect the cells of the columnar epithelium of the respiratory tract. General pathomorphological changes in ARVI:
- cytoplasmic and intranuclear destruction of epithelial cells;
- disruption of the functional activity and integrity of the cilia and, consequently, mucociliary clearance;
- dystrophic changes in the epithelium and the possible appearance of serous or serous-hemorrhagic exudate in the lumen of the alveoli.
Although all respiratory viruses cause diseases with similar clinical pictures, characteristic features have been identified that allow one to assume with a sufficient degree of probability the etiology of the infectious disease.