Children's respiratory syncytial virus pneumonia

　　1. Etiology

　　Respiratory syncytial virus (respiratory syncytial virus, RSV), abbreviated as RSV, belongs to the Paramyxoviridae family, and is the most common pathogen causing viral pneumonia in children, which can cause interstitial pneumonia and bronchiolitis. Under the electron microscope, the appearance of RSV is similar to that of parainfluenza virus, with virus particle size of about 150nm, slightly smaller than parainfluenza virus, being an RNA virus sensitive to ether, without hemagglutinating activity, forming a unique syncytium in human epithelial tissue culture, and multiplying in the cytoplasm, where cytoplasmic inclusions can be seen. RSV has only one serotype, and recent molecular biological methods have proven that there are 2 subtypes, A and B.

　　2. Pathogenesis

　　The incubation period of respiratory syncytial virus infection is 2-8 days (usually 4-6 days). The typical manifestations of respiratory syncytial virus pneumonia are interstitial infiltration of mononuclear cells. The main manifestations are widened alveolar septa and interstitial exudation dominated by mononuclear cells, including lymphocytes, plasma cells, and macrophages. In addition, the alveolar spaces are filled with edema fluid, and pulmonary hyaline membrane formation can be seen. In some cases, lymphocytic infiltration of the bronchiolar wall can also be seen. Edema with necrotic areas appears in the lung parenchyma, leading to alveolar obstruction, consolidation, and atrophy. In a few cases, multinucleated fused cells can be seen in the alveolar spaces, resembling morbilli giant cells in morphology, but no intranuclear inclusions can be found. Gardner (1970) dissected a case of respiratory syncytial virus pneumonia death, detected a large amount of respiratory syncytial virus using fluorescence antibody testing, and found no human globulin deposition, believing that the pneumonia lesions may be primarily due to direct invasion of the lung by respiratory syncytial virus, not due to hypersensitivity.

　　Severe cases may develop concurrent heart failure and respiratory failure. Heart failure (heart failure) is a group of syndromes caused by various diseases of cardiac structure or function, leading to impaired ventricular filling and (or) ejection function. Due to the decrease in ventricular contraction function and impaired ejection function, cardiac output cannot meet the needs of the body's metabolism, resulting in insufficient blood perfusion to organs and tissues. At the same time, there is pulmonary circulation and (or) systemic circulation congestion. The main clinical manifestations are dyspnea, weakness, and restriction of physical activity, and edema. The treatment of this disease should include preventing and delaying the occurrence of heart failure, alleviating the symptoms of clinical heart failure, improving its long-term prognosis, and reducing mortality.

　　This disease is more common in infants and young children, with more than half being infants under one year old. Boys are more than girls, with a ratio of about 1.5～2:1. The incubation period is about 4～5 days. In the early stage, symptoms such as cough and nasal obstruction can be seen. About 2/3 of the cases have a high fever, which can reach up to 41℃, but the fever is generally not persistent and is easier to reduce with antipyretic drugs. The duration of high fever is usually 1～4 days, with a few cases lasting 5～8 days. About 1/3 of the children have moderate fever, which usually lasts for 1～4 days. The duration of fever in most cases is 4～10 days. In mild cases, there may be difficulty breathing without significant neurological symptoms; in moderate to severe cases, there may be more obvious difficulty breathing, wheezing, cyanosis of the lips, nasal flaring, and tracheal depression. A few severe cases may also develop heart failure. Auscultation of the chest often shows fine or coarse, medium rales, and percussion is generally non-turbid. A few cases may have hyperresonance. In 1998, the Capital Institute of Pediatrics conducted an initial summary of the clinical features of 22 children with RSV bronchiolitis of A subtype, finding that most of the children were infants, with 82% being infants aged 1 to 6 months, and the male to female ratio was 4.5:1. The fever was generally below 38℃ (54%), and symptoms such as wheezing appeared 2 days after onset (64%). Chest X-rays mainly showed patchy shadows in both lungs (77%) and emphysema shadows (64%).

　　Respiratory syncytial virus is highly contagious, often causing outbreaks. Literature reports indicate that secondary respiratory syncytial virus infections in hospitals can reach 30% to 50%. In autumn and winter, with large fluctuations in temperature, it is important to prevent respiratory diseases. First of all, attention should be paid to keeping warm. Additionally, autumn and winter are very dry, with high levels of air dust, which can easily damage the nasal mucosa. Therefore, it is necessary to drink more water to keep the mucosa moist. Moreover, avoid going to public places with poor air circulation and appropriately supplement vitamins, especially vitamin C. Pay attention to the isolation and treatment of early patients. In recent years, research on RSV vaccines has mainly focused on subunit vaccines, live attenuated vaccines, peptide vaccines, genetically engineered vaccines, nucleic acid vaccines, etc., all of which have made certain progress.

　　1. The total white blood cell count in blood is generally (5～15)×10^9/L, most of which is below 10×10^9/L, with neutrophils accounting for less than 70%.

　　2. The diagnosis of this disease mainly relies on virological and serological examination results. In recent years, rapid diagnosis of respiratory syncytial virus infection can be achieved through indirect immunofluorescence techniques using nasal pharyngeal secretion desquamated cells and serum IgM antibodies, ELISA, alkaline phosphatase-antialkaline phosphatase bridging enzyme labeling method (APAAP), biotin-avidin ELISA method, horseradish peroxidase-antihorseradish peroxidase method (PAP), and monoclonal antibody fluorescence method, etc.

　　1. Consume high-nutrient, easily digestible foods. Staple foods can include rice, noodles, steamed buns, bread, etc., while side dishes should include more meat, fish, eggs, poultry, and soy products. Generally, one egg is added to breakfast, and 2-3 ounces of meat to each lunch and dinner.

　　2. For high fever and loss of appetite, semi-liquid foods such as rice porridge, buns, wontons, etc., can be eaten. Side dishes such as minced meat stewed eggs, meatballs, steamed fish, etc., should be eaten 1 meal every 2-3 hours, with a total of 6 meals a day. Liquid foods such as milk, soy milk, rice gruel, malt milk powder, lotus root starch, meat soup, chicken soup, stewed eggs, etc., can also be eaten, with a total of 6 meals a day. Since liquid foods provide insufficient calories and nutrients, they should not be used for a long time.

　　3. Eat more fruits and vegetables that clear heat and moisten the throat, such as pears, watermelons, cucumbers, winter melons, water chestnuts, tangerines, etc.

　　4. Avoid spicy and salty foods.

　　I. Treatment

　　I. General treatment

　　Special attention should be paid to general treatment, isolation, and efforts to prevent secondary bacterial or other viral infections. If there is no secondary bacterial infection, only traditional Chinese medicine treatment is needed. General treatment can refer to bronchopneumonia, and other conditions can refer to adenovirus pneumonia. Since this disease is mild, it does not require so many symptomatic and supportive treatments. Ultrasonic nebulization and back tapping to remove sputum are simple and effective respiratory treatment methods. Not only do they help humidify the airways and clear inflammatory secretions, but also by relieving obstruction and improving ventilation, they can correct respiratory acidosis and even type II respiratory failure in severe cases more quickly, avoiding the misuse and overuse of alkaline drugs. Chinese research has shown that traditional Chinese medicine with double yellow连 nebulization inhalation has a significant effect on RSV pneumonia and bronchiolitis.

　　II. Antiviral treatment

　　Regarding antiviral chemical drugs, ribavirin (triazine nucleoside) nebulization therapy can be used for severe cases. Recently, some people in foreign countries have found that short-term high-dose nebulization therapy is effective for respiratory syncytial virus infection. In addition, Shanghai Xinhua Hospital uses whey liquid (colostrum diluent) for nebulization therapy of lower respiratory tract infection with respiratory syncytial virus, Wenzhou Medical College extracts SIgA from colostrum for nebulization inhalation therapy of respiratory syncytial virus pneumonia, and has achieved good results, which can be applied.

　　II. Prognosis

　　This disease is generally mild, and simple cases recover clinically in 6-10 days. X-ray shadows usually disappear in 2-3 weeks. If isolation measures are not effective, secondary infections are likely, and fever may recur. Simple respiratory syncytial virus pneumonia is rarely fatal.