Acute upper respiratory tract infection in children

　　1. Etiology

　　Viral infections account for more than 90% of primary upper respiratory tract infections. Mycoplasma and bacteria are less common. After viral infection, the mucous membrane of the upper respiratory tract loses resistance, allowing bacteria to take advantage and cause secondary infections.

　　1. Common Viruses

　　(1) Rhinovirus: There are more than 100 different serotypes, and the isolation of coronaviruses requires special methods. Both are common pathogens. Their symptoms of infection are confined to the upper respiratory tract, mostly in the nose.

　　(2) Parvovirus and ECHO virus: These viruses are all very small and belong to Picomavims, commonly causing inflammation of the nasopharynx.

　　(3) Influenza virus: It is divided into three serotypes - A, B, and C. Type A can cause pandemics due to its antigenic structure undergoing more drastic mutations, and is estimated to occur every 10 to 15 years. Type B has a smaller scale of epidemic and is more localized. Type C generally only causes sporadic outbreaks, with mild symptoms. These three types mainly cause upper respiratory infections in children, and can also cause laryngitis, tracheitis, bronchitis, capillary bronchitis, and pneumonia.

　　(4) Parainfluenza virus: It is divided into four serotypes. Type 1 is known as 'Hemagglutinin 2' (HA2); Type 2 is known as 'Croup-like virus 1' (HA1), which often causes bronchiolitis or pneumonia, and is also frequently associated with croup; Type 3 is endemic, can occur throughout the year, is highly infectious, and can cause tracheitis and pneumonia in infants, with most infected before the age of 1; Type 4, also known as M-25, is less common, and can cause upper respiratory infections in children and adults.

　　(5) Respiratory syncytial virus (respiratory syncytial virus): There is only one type, which has strong pathogenicity to the respiratory tract of infants and young children, and can cause small outbreaks. About 75% of infants under 1 year of age develop bronchiolitis, and about 30% suffer from laryngitis, tracheitis, bronchitis, and pneumonia. After the age of 2, the incidence of bronchiolitis decreases. After the age of 5, it only manifests as mild upper respiratory tract infections, and lower respiratory tract infections decrease significantly. The latter three viruses mentioned above all belong to mucoproteins. In acute upper respiratory tract infections, parainfluenza virus, respiratory syncytial virus, and coronavirus are more common.

　　(6) Adenovirus (adenovirus): There are 41 different serotypes, which can cause upper respiratory tract infections of varying severity, such as nasopharyngitis, pharyngitis, pharyngo-conjunctivitis, follicular conjunctivitis, and can also cause outbreaks of pneumonia. Type 3 and 7 adenoviruses can persist in the upper respiratory tract glands and cause fatal pneumonia. Type 8 adenovirus is easy to cause epidemic keratoconjunctivitis in school-age children. Types 3, 7, and 11 can cause pharyngitis and conjunctivitis. In the summer of 1979 to 1983, an outbreak of type 3 and 7 adenovirus pharyngoconjunctivitis was caused by swimming in Beijing.

　　2. Mycoplasma pneumoniae

　　Also known as Pneumoplasma or pleuropneumonic-like microorganisms (abbreviated as PPLO), it not only causes pneumonia but can also cause upper respiratory tract infections, with pneumonia more common in children aged 5 to 14 years.

　　3. Common Bacteria

　　It accounts for about 10% of primary upper respiratory tract infections. Secondary bacterial infections侵入上 respiratory tract are mostly caused by group A β-hemolytic streptococcus, pneumococcus, Haemophilus influenzae, and staphylococcus, among which streptococcus often causes primary pharyngitis. Corynebacterium catarrhalis, one of the common flora of the nasopharynx, can sometimes develop into pathogenic bacterial infections in the respiratory tract and has an increasing trend, but it is less than that of Streptococcus pneumoniae and Haemophilus influenzae infections. Inducing factors include malnutrition, lack of exercise, or overexertion, as well as children with allergic constitution, who are prone to upper respiratory tract infections due to reduced body defense ability. Especially in children with dyspepsia, rickets, primary immune deficiency diseases, or acquired immunodeficiency due to postnatal immunodeficiency, serious symptoms often occur when concurrent infections occur. In the winter and spring seasons with frequent changes in climate, it is more likely to cause an epidemic. It must be pointed out that the occurrence and development of upper respiratory tract infections not only depend on the type, virulence, and quantity of the pathogens侵入, but are also closely related to the host's defense function and environmental factors. Living in crowded conditions, air pollution, passive smoking, and indirect inhalation of smoke can all reduce the local defense ability of the respiratory tract, promoting the growth and reproduction of pathogens. Therefore, strengthening exercise, improving nutritional status and environmental hygiene is very important for preventing upper respiratory tract infections.

　　Second, pathogenesis

　　Children are prone to respiratory tract infections due to imperfect defense function. Insufficient secretion of respiratory tract mucus glands, poor ciliary movement, and thus, the physical non-immunological defense function is relatively poor in children compared to adults. Insufficient production of secretory IgA makes the airways susceptible to microbial invasion. Transmission occurs through droplets containing viruses, mist, or contaminated objects. Often, when the body's resistance is reduced, such as when exposed to cold, fatigue, or rain, viruses and (or) bacteria that are already present or have entered from the outside grow and multiply rapidly, leading to infection. In addition, due to the existence of bronchial hyperreactivity, some infants may诱发 respiratory allergic diseases due to respiratory tract infections and other factors.

　　If acute upper respiratory tract infection is not treated in time, it can cause many complications, especially more common in the infantile period. Complications can be divided into three major categories:

　　1. The infection spreads from the nose and throat to nearby organs, with acute conjunctivitis, sinusitis, stomatitis, laryngitis, otitis media, and cervical lymphadenitis being more common. Other conditions such as post-pharyngeal abscess, peritonsillar abscess, maxillary osteomyelitis, bronchitis, and pneumonia are also not uncommon.

　　2. The pathogen spreads throughout the body through the blood circulation. When bacterial infection is accompanied by sepsis, it can lead to suppurative foci such as subcutaneous abscesses, empyema, pericarditis, peritonitis, arthritis, osteomyelitis, meningitis, brain abscess, and urinary tract infections.

　　3. Due to the变态反应 effect of the infection on the body, diseases such as rheumatic fever, nephritis, myocarditis, hepatitis, purpura, rheumatoid arthritis, and other connective tissue diseases may occur.

　　1. Incubation period

　　It usually lasts for 2 to 3 days or a little longer.

　　2. Mild

　　Only nasal symptoms, such as clear nasal discharge, nasal congestion, sneezing, etc., can also include tears, light cough, or discomfort in the throat. These symptoms can naturally resolve within 3 to 4 days. If the infection involves the nasopharynx, fever, throat pain, tonsillitis, and hyperemia and hypertrophy of the lymphoid tissue at the posterior wall of the pharynx are common. Sometimes, the lymph nodes can become slightly swollen, with fever lasting for 2 to 3 days to about 1 week. In infants and young children, it often causes vomiting and diarrhea.

　　3. Severe

　　The body temperature can reach 39～40℃ or higher, accompanied by chills, headache, general weakness, decreased appetite, restless sleep, and other symptoms. Coughs that occur more frequently due to nasal and pharyngeal secretions, a slightly red throat, and the occurrence of herpes and ulcers are called herpangina. Sometimes, the redness and swelling are significant enough to involve the tonsils, with the appearance of follicular purulent exudates, exacerbation of throat pain and systemic symptoms, nasal and pharyngeal secretions changing from thin to thick, the submandibular lymph nodes becoming significantly swollen and tender. If the inflammation spreads to the paranasal sinuses, middle ear, or trachea, corresponding symptoms may occur, with systemic symptoms also being severe. Attention should be paid to high fever convulsions and acute abdominal pain, and differential diagnosis should be made with other diseases. Acute febrile convulsions caused by acute upper respiratory tract infection are more common in infants and young children, occurring within 1 day after onset and rarely recurring. Acute abdominal pain can be very severe, often around the umbilicus, without tenderness, appearing early and usually temporary, possibly related to increased intestinal peristalsis; it can also persist, sometimes resembling the symptoms of appendicitis, often due to concurrent acute mesenteric lymphadenitis.

　　4. Acute tonsillitis

　　It is part of acute pharyngitis, and its course and complications are not exactly the same as those of acute pharyngitis, so it can be considered as a separate disease or incorporated into pharyngitis. Sometimes, in the surface of the tonsils of those caused by viruses, there can be spotted white exudates. At the same time, small ulcers can be seen on the soft palate and the posterior wall of the pharynx. Bilateral buccal mucosa is congested with scattered hemorrhagic spots, but the mucosal surface is smooth, which can be distinguished from measles. Those caused by Streptococcus usually occur in children over 2 years old, with more systemic symptoms during the onset, such as high fever, chills, vomiting, headache, abdominal pain, etc. After that, the throat pain may be mild or severe, swallowing may be difficult, and the tonsils are mostly diffusely red and swollen or show follicular purulent exudates at the same time. The patient's tongue is red with thick fur. If not treated in time, it is easy to develop sinusitis, otitis media, and cervical lymphadenitis.

　　5. Course of disease

　　The fever duration of mild cases varies from 1-2 days to 5-6 days, but severe cases can have a high fever for 1-2 weeks, and occasionally, there may be a long-term low fever lasting for several weeks. Since the focus has not been cleared, it takes a longer time to recover.

　　1. Positive exercise

　　It is very important to use natural factors to exercise the body, such as frequently opening windows for sleep, outdoor activities, and sports, which are positive methods. As long as they are persistent and regularly practiced, they can enhance physical fitness and prevent upper respiratory tract infections.

　　2. Maintain hygiene and avoid triggers of disease

　　Wearing too many or too few clothes, excessive or low room temperature, sudden changes in weather, environmental pollution, and passive smoking are all causes of upper respiratory tract infections, and precautions should be taken.

　　3. Avoid cross-infection

　　Wash hands after contacting a sick child, and wear a protective suit if necessary. Isolation not only protects nearby children but also can reduce the occurrence of complications in the sick child. This can be implemented in general kindergartens and hospitals, and adult patients at home should avoid contact with healthy children. The ward should be ventilated and the air exchanged, maintaining a suitable temperature, disinfecting the beds of discharged patients and keeping clean empty beds ready for immediate reception of new patients. If conditions permit, ultraviolet light can be used to disinfect the ward and contaminated areas to prevent the spread of pathogens.

　　4. Drug Prevention

　　Kasuan, 5ml for infants and children, 10ml for children, taken orally, 3 times a day, 3-6 months as a course of treatment. Levamisole, 2.5mg (kg/d), taken for 2 days a week, 3 months as a course of treatment. Astragalus, 6-9g per day, taken continuously for 2-3 months. These drugs can enhance the immune function of cells and body fluids, and can reduce the frequency of recurrence after repeated upper respiratory tract infections in children. External therapy of traditional Chinese medicine, such as Baicao Qiangjiang Yiqi paste, can strengthen the lung function of children and improve their immunity. The modified Yu Ping Feng San (formula: 9g raw Astragalus, 6g Baizhu, 3g Fangfeng, 9g raw Oyster Shell, 6g Chenpi, 9g Shanyao, ground into fine powder) is taken twice a day, 3g each time, taken orally.

　　5、注射疫苗

　　It is recently believed that the use of attenuated virus vaccines, administered by nasal drops and/or nebulization, can stimulate the production of secretory IgA antibodies in the nasal and upper respiratory tract mucosa, thereby enhancing the respiratory tract's defense against infection. A large number of research studies indicate that secretory IgA has a better effect against respiratory tract infections than any serum antibody. Due to the many types of enteroviruses and rhinoviruses, it is difficult to carry out vaccine prevention.

　　1. Blood count

　　White blood cell count classification is of certain significance in distinguishing between viral or bacterial infections. The former has a normal or low white blood cell count, while the latter usually has an increased total white blood cell count. This disease is mostly viral infection, with a low or normal white blood cell count, but a higher percentage of neutrophils in the early stage. In cases of bacterial infection, the total white blood cell count is usually increased, and it can also decrease in severe cases, but the percentage of neutrophils remains high.

　　2. Electrocardiogram

　　If necessary, perform an electrocardiogram to determine whether there is myocardial damage.

　　3. X-ray examination

　　Perform chest X-ray examination to determine whether there are complications such as bronchitis or pneumonia.

　　1. Actively exercise to strengthen physical fitness;

　　2. Do not wear too many clothes in daily life, and adjust clothing according to temperature changes;

　　3. Avoid contact with patients, try not to take children to public places during the epidemic season of upper respiratory tract infection, and masks or traditional Chinese medicine such as Isatis indigotica and Isatis tinctoria can be taken for prevention if necessary;

　　1. Treatment

　　The main treatment is to ensure adequate rest, relieve exterior symptoms, clear heat, and prevent complications, while paying attention to general care and supportive therapy.

　　1. Drug therapy

　　The treatment methods include etiological therapy and supportive therapy. In etiological therapy, traditional Chinese medicine is often used for viral infections. Some people extract secretory IgA from colostrum for nasal drops, at a dose of 0.3-0.5mg/(kg·d), administered 6-8 times, for 2-3 consecutive days, with good efficacy. For bacterial infections, penicillin and other antibiotics are used. Most acute upper respiratory tract infections are caused by viral infections, and antibiotics are not only ineffective but can also cause dysbiosis of the body's flora, so it is necessary to avoid abuse. When complications such as pharyngitis or tonsillitis caused by group A beta-hemolytic streptococcus occur, penicillin is effective. If it is ineffective after 2-3 days, other pathogens should be considered. For high fever, apply a cold towel to the forehead and the entire head first. In addition, general antipyretics such as aspirin or acetaminophen (paracetamol) can be used, which can be repeated every 4-6 hours according to the condition, but avoid excessive dosage to prevent sudden drop in body temperature, excessive sweating, or even fainting. For children with mild cough, especially infants, it is not advisable to use large amounts of cough suppressants, either Chinese or Western medicine.

　　2. Local Treatment

　　If there is a rhinitis, to ensure the airway is clear and to ensure rest, children's nasal drops should be used before meals and before bedtime, 4-6 times/day, 2 drops per nostril. Infants should avoid using oil-based nasal drops, as it may be inhaled into the lower respiratory tract and cause lipoid pneumonia. Older children with pharyngitis or tonsillitis can gargle with diluted salt water or boric acid solution.

　　3. Traditional Chinese Medicine Treatment

　　Upper respiratory tract infection is called 'Shangfeng common cold' in traditional Chinese medicine. According to clinical manifestations, it can be divided into wind-cold common cold and wind-heat common cold. In traditional Chinese medicine, influenza is called 'Shi Xing common cold', which has similar clinical manifestations to wind-heat common cold and belongs to severe cases of wind-heat common cold. ②Excessive heat can easily cause convulsions (heat convulsion); ③It is prone to cause gastrointestinal symptoms such as vomiting and diarrhea due to food retention. Regardless of wind-cold or wind-heat, the disease location is on the exterior, and the treatment should use the method of resolving the exterior, using acrid-warm resolving the exterior for wind-cold type and acrid-cooling resolving the exterior for wind-heat type. In addition, tonsillitis is a common disease among upper respiratory tract infections, and its traditional Chinese medicine treatment will be described together.

　　(1) Common cold: ①Wind-cold common cold: Common in the early stage of common cold in older children, with symptoms such as aversion to cold, fever, no sweating, runny nose, headache and body pain, cough with phlegm, pale red tongue, thin white tongue coating, floating and tense pulse. Treatment is based on acrid-warm resolving the exterior. Example prescription: 9g of musk, 9g of chrysanthemum, 6g of Su Gen, 3g of Jingjie, 9g of Forsythia, 9g of Gypsum fibrosum. ②Wind-heat common cold: Common in infants and young children, with severe fever, or sweating but not relieved, nasal congestion, runny yellow nose, flushed face, red throat, or cough with phlegm, slightly red tip of tongue, thin white or yellowish tongue coating, floating and rapid or slippery and rapid pulse. Treatment is based on acrid-cooling resolving the exterior and clearing heat and detoxifying. Example prescription one (for those with severe exterior heat): 9g of Lonicera japonica, 9g of Forsythia, 6g of Mentha haplocalyx, 9g of Isatis, 15g of Gypsum fibrosum, 9g of Arctium lappa. Example prescription two (for those with severe interior heat): 9g of Lonicera japonica, 9g of Forsythia, 9g of chrysanthemum, 3g of Indigo naturalis, 9g of Lycium barbarum, 9g of Radix rehmanniae, 9g of Isatis, 9g of Gypsum fibrosum.

　　(2) Influenza: The onset is acute, and the condition is relatively severe. General symptoms are more obvious, and it is prone to manifesting as 'Yingfen syndrome', which can be treated with the method of treating common cold with wind-heat, combined with clinical adjustment. According to the types of common cold mentioned above, the following drugs can be added according to the symptoms: ①In case of high fever, add 6g of Scutellaria baicalensis; for those with dry stool due to high fever, add 0.3-0.6g of Xiao'er Niuhuang San, taken 2-3 times a day. ②During the summer, for colds with high fever, fatigue, nausea, vomiting, greasy tongue coating, add 6g of musk and 6g of Peilan. ③For severe cough, add 9g of Qianhu and 6g of杏仁. ④For high fever with convulsions, add 9g of Uncaria rhynchophylla, 6g of Cantharis or 15g of mother-of-pearl. ⑤For those with food retention, add 9g of Jiaozha, 9g of Jianqu or 6g of Daikon seed.

　　(3) Acute tonsillitis: Known as 'milky goiter' in traditional Chinese medicine, it is divided into 'red and swollen throat goiter' (equivalent to acute tonsillitis) and 'lotus flower goiter' (equivalent to cryptogenic acute tonsillitis) according to different clinical manifestations. During the acute stage, the main therapy is to clear heat and relieve fire, detoxify and reduce swelling, while external treatment methods can also be applied. Prescription example: 9g of Lonicera japonica, 9g of Forsythia, 3g of Mycoderma, 9g of Isatis, 9g of Belamcanda, 15g of Scrophularia, 9g of Swertia, 3g of indigo. The following drugs can be added according to the symptoms: ①For those with severe exterior heat, add 30g of fresh Phragmites australis, 9g of chrysanthemum, and 6g of mint for those without sweating. ②For those with severe internal heat, add 15g of raw gypsum, 6g of Scutellaria for those with high fever, thirst, and sweating; for those with red tongue and no sweating due to high fever, add 6g of Danpi. ③For those with dry stool, add 6g of raw rhubarb, decocted separately and taken together, and stop taking it when the stool is smooth. ④For those with submandibular lymph node swelling and pain, add 9g of Prunella, 6g of Bupleurum, and 9g of Chuanxiong. In addition, locally, you can use tin powder or ice borax powder to blow into the throat, a little on each side, 2-3 times a day. For seriously ill infants and young children, the cough reflex may be weakened, and caution should be exercised when blowing medicine into the throat, with a small amount of medicine to prevent aspiration during crying and struggling.

　　4. Treatment of complications

　　The treatment of common complications is an important link in dealing with acute upper respiratory tract infection, and appropriate measures must be taken according to the severity and urgency.

　　5. General care

　　Pay attention to rest and care, during the fever period, it is advisable to provide liquid or soft food, drink plenty of water; for breastfeeding infants, feed them in small amounts and multiple times to avoid digestive symptoms such as vomiting and diarrhea. Keep the room temperature constant, maintain a certain humidity, and pay more attention to symptoms of laryngitis. To relieve sore throat and neck lymph node pain, older children can use cold or hot compresses. When there is excessive nasal pharyngeal secretion, assume a prone position.

　　II. Prognosis

　　The prognosis of this disease is good, with self-limiting nature, generally recovering within 5 to 7 days. General symptoms such as spirit and appetite are often more important than body temperature and white blood cell count. Those who eat and drink normally have a good prognosis; those with listlessness, excessive sleepiness, or restlessness and pallor should be vigilant.