Beijing, July 7 -- Friends with children at home may have noticed that since March this year, the phenomenon of repeated fever and cough in children has increased. Pediatricians introduced that in previous years, the peak of respiratory infections in children in northern China was generally in winter, but the peak period of spring and summer this year was endless, which was exceptionally long, and the culprit was it - respiratory syncytial virus.
Recently, Lv Fang, attending physician of the Department of Critical Care Medicine of the Children's Hospital Affiliated to the Capital Institute of Pediatrics, published a popular science article introducing the prevention and treatment methods and precautions of respiratory syncytial virus.
In the past three years, due to the new crown epidemic, everyone has taken protective measures such as wearing masks and maintaining social distance, the incidence of respiratory infections in children has been significantly reduced, and the immunity of the population against various respiratory viruses has also been generally reduced, so this year's respiratory syncytial virus is more ferocious than in previous winters.
This is an RNA virus first identified in 1956 isolated from chimpanzee respiratory specimens. It is named respiratory syncytial virus because it causes adjacent cells to fuse during culture, and cytopathic to form syncytia-like structures. The population is generally susceptible, which is the most common cause of respiratory infections in children, and it is also the most common cause of bronchitis and pneumonia in children under 1 year of age, and infections in school-age children are not uncommon. It has only one serotype, but there are two subtypes, A and B, both of which can occur simultaneously in a region, and type A is often more severe. Similar to influenza viruses, there are several genotypes in this virus subtype, and the dominant strain rotates from year to year, so children can be reinfected frequently. Like the new coronavirus, the same person can be infected more than once, but the subsequent infection is usually milder than the first time. Some children were infected with respiratory syncytial virus pneumonia in early May, and coughed again in June, this time it was bronchitis caused by respiratory syncytial virus. Or once last year and again this year. But overall, the disease is self-limiting and does not cause significant long-term lung sequelae, so parents should not worry too much.
Where does it come from? RSV is transmitted mainly through direct contact, but can also be transmitted by droplets and aerosols. The virus is present in the nasopharynx of the patient, the excretion time is 3-11 days, in small infants up to 4 weeks. Infection in infants and young children usually occurs after an older brother or sister is infected. The incubation period is 2-8 days, mostly 4-6 days. That is, the baby is sick within a week of the family catching a cold, and may be infected by the family. If it has been more than a week, it has little to do with the family's cold. In children, generally the younger the age, the weaker the resistance and the shorter the incubation period is usually shorter.
What does infection with this virus look like? The virus replicates in the nasopharynx and infects bronchiole epithelial cells and then spreads to type I and II alveolar cells of the lung. The initial symptoms are cold symptoms such as nasal congestion and runny nose, and symptoms of lower respiratory tract infection such as coughing and wheezing appear 1-3 days later. The degree of fever can be high or low, low-grade fever is common, usually no more than 3-5 days, or no fever, but cough is usually more severe, nocturnal cough frequently interferes with sleep, lasting 1-2 weeks, or even 4 weeks, wheezing is common in infants and young children. Vomiting after coughing is a common manifestation of respiratory infections in children, and if it is 1-2 times a day, it is generally not a big problem. Decreased appetite is also common, usually returning to normal within a week, and if you are in good spirits and urine a lot, you can observe it at home. Severe cases may present with irritability, nasal flapping, sunken chest, moaning, shortness of breath, dyspnea, or cyanosis. The following complications can also occur: sinusitis, otitis media, dehydration, apnea, respiratory failure, secondary bacterial infections, etc. Respiratory syncytial virus infection in some infants is also associated with recurrent wheezing.
Respiratory syncytial virus can cause severe bronchiolitis or pneumonia, who is at high risk of severe disease? 1. Infants under 6 months of age, recent brother or sister with cold symptoms 2. Underlying diseases, such as bronchopulmonary dysplasia, cystic fibrosis, bronchial asthma, congenital heart disease, neurological diseases, etc. 3. Premature infants, especially those born before 35 weeks, low birth weight infants (birth weight less than 2.5 kg) 4. Exposure to secondhand smoke 5. HIV exposure but not infected 6. Down syndrome 7. Immunocompromised patients such as severe combined immunodeficiency disease, leukemia, hematopoietic stem cell transplantation, etc. 8. Residents of areas above 2500 meters above sea level 9. Elderly people admitted to shelter and nursing institutions 10. Elderly patients with chronic diseases or functional disabilities.
What situations do I need to go to the hospital? If the child has a cough at night that affects sleep, high fever lasts for more than 3-5 days, shortness of breath or difficulty breathing, irritability or lethargy, a significant decrease in urine output (such as 6-8 hours of anuria), cyanosis and other manifestations, it is recommended to go to the hospital as soon as possible. It should be emphasized that the child's illness should see the spirit, and when the spirit is not good, he should seek medical attention as soon as possible.
How is it diagnosed? Similar to the new coronavirus, the method of PCR can be used to detect viral nucleic acid, which is currently the most commonly used method, but it usually takes 2-3 hours. Primary hospitals can also use antigen detection methods, the advantage is that the results are available within 30 minutes, the disadvantage is that the sensitivity is lower than the method of nucleic acid detection, so the positive rate is lower. Serological antibody testing is not helpful in the evaluation of RSV infection, especially early in the course of the disease. It takes 5-7 days for antibodies to be produced, so it is not necessary to draw blood for this test within 5-7 days of onset. The same is true for other pathogen infections, for example, many parents ask the doctor to draw blood to check for Mycoplasma pneumoniae antibodies when their children have a fever for 1 day, in fact, it is meaningless to check at this time, and the positive test can only reflect the recent infection with Mycoplasma pneumoniae, and can not indicate that the fever is caused by it.
What tests are needed? Low-grade or no fever usually do not need to do a blood routine, ordinary children do not need to take a chest x-ray, for those with moderate or severe respiratory distress, such as nasal flapping, chest depression, moaning, respiratory rate greater than 60 beats per minute or cyanosis should take a chest x-ray. Critically ill children require monitoring of transcutaneous oxygen saturation. In Beijing, the hospital emergency pre-examination triage system has been in place for more than four years, and triage nurses will measure the blood oxygen saturation of each patient who comes to the emergency department. If the blood oxygen saturation above 95% is normal, it belongs to grade 4, and the blood oxygen saturation is less than 95% is abnormal, priority can be given to the doctor, of which 90-94% is grade 3, 85-89% is grade 2, and less than 85% is grade 1. The higher the level, the more severe the disease.
How is it treated? Many people think that children have pneumonia and must be infusions to get better. In fact, simple viral infections usually do not require antibiotics (cephalosporins or azithromycin). At present, there are no targeted antiviral drugs, mainly to support and symptomatic treatment, including antipyretic, severe patients need to monitor blood oxygen saturation, small infants with a lot of sputum should suction to keep the airway unobstructed, asthma obvious can use bronchodilators and hormone atomization, oral Chinese proprietary medicine and Western medicine to suppress cough and phlegm (the guidelines within 6 years old do not recommend cough and phlegm Western drugs). If intravenous fluids are required when the urine is low, and in severe cases, oxygen, noninvasive or invasive mechanical ventilation respiratory support, usually within a week, the ventilator can be withdrawn.
How can it be prevented? Handwashing and contact protection are important measures to prevent respiratory infections. Despite the end of the pandemic, hospitals are still gathering places for various pathogens, and it is recommended that everyone wear masks to the hospital. Family members should wash their hands frequently after catching a cold, and ventilate the room more. Also pay attention to cough hygiene, such as covering your mouth and nose with your sleeves or elbows when sneezing, disposing of used tissues in the trash immediately and washing your hands. During the epidemic season, high-risk groups try not to go to crowded and poorly ventilated places, such as shopping malls and supermarkets. At present, there is no respiratory syncytial virus vaccine on the market at home and abroad, and several vaccines are still in the clinical research and development stage.
Like other microbes on Earth, respiratory syncytial virus is an ancient virus that has been coexisting with humans for so long that we cannot eliminate it. Infection with this virus is not very dangerous for patients without high-risk factors, but for high-risk groups, early identification and timely medical treatment are the key to reducing the case fatality rate. (Lv Fang, attending physician, Department of Critical Care Medicine, Children's Hospital, Capital Institute of Pediatrics)