Source: Center for Infectious Disease Quality Control
As young people born in the 1980s and 1990s enter the peak of marriage and childbirth, and China fully liberalizes the second-child policy, the latest data from the National Bureau of Statistics shows that in 2019, there were 14.65 million newborns; more than 100 million preschool children aged 1 to 6. In the process of raising preschool children, parents’ biggest concern is undoubtedly the physical health of their babies.
Acute respiratory infection is one of the most common diseases in childhood, especially in infants and young children under two years of age. In my country, pneumonia is the main cause of death in children under 5 years old, and the main pathogen of pneumonia in children is viruses, among which respiratory syncytial virus is the first pathogen of pneumonia in children!
Let’s learn about respiratory syncytial virus (RSV) today.
1. What is respiratory syncytial virus (RSV)?
Respiratory syncytial virus, referred to as RSV in English, belongs to RNA virus. Like the new coronavirus and influenza virus we know, it is one of the pathogens that cause acute respiratory infection in children.
RSV was isolated from the chimpanzee respiratory tract in 1956. It is called respiratory syncytial virus because it causes adjacent cells to fusion during cell culture and cell lesions to form a syncytial-like structure.
RSV is very easily contagious and spreads through direct contact and droplets. RSV is mainly contagious through contact with the nasopharyngeal mucosa of virus-containing body fluids, sweat or contaminants. Direct contact is the most common transmission route. In 2020, the "Expert Consensus on Diagnosis, Treatment and Prevention of Syncytial Virus Infection in Children" released by the Respiratory Group of the Pediatric Branch of the Chinese Medical Association also emphasized that droplets and aerosols can also cause RSV transmission. RSV can survive on hands and contaminants for several hours, so frequent hand washing and contact protection (wearing a mask) are important measures to prevent the spread of respiratory viruses, including RSV.
RSV can be infected all year round. The epidemic period in northern my country is from October to May of the following year, and the epidemic in the south is not obvious. RSV is widely popular around the world, and its popularity is affected by factors such as geographical location, temperature and humidity. Zhang Yaowen and others from Beijing Sino-Japanese Friendship Hospital conducted a meta-analysis of 135 studies through systematic search of the China Biomedical Database (CBM), China National Knowledge Infrastructure (CNKI), Wanfang Database and PubMed Database, revealing the epidemic characteristics of RSV in my country: the peak period of infection in winter and spring, and the remaining months were sporadic, and overlapped with the influenza virus epidemic period ; December to February is the peak period of RSV epidemic in the country; from geographical perspective, central, northwest and southwest my country are high-incidence areas; among which, Hainan and Guangdong are relatively hot, the seasonal epidemic of RSV is not obvious.
RSV infection latency is 1-10 days, usually 5-7 days. In the early stage of RSV infection, most of them are limited to the upper respiratory tract, and clinically manifested as upper respiratory tract symptoms, such as nasal congestion, runny nose, cough, hoarseness, etc., accompanied by fever, and there may be no obvious symptoms; symptoms such as lower respiratory tract cough, wheezing, rapid breathing frequency, and restlessness will gradually appear 2-5 days after the infection. In severe cases, there will be "three concave signs" when inhaling. It is difficult for parents to identify and distinguish early symptoms; for children under two years old, RSV infection can rapidly progress to lower respiratory tract infection, mainly manifested as bronchiolitis or pneumonia. If treatment is not done in time, life may be in danger.
2. The RSV infection rate is high, and it is prone to repeated infections
RSV infection is highly contagious and very easy to invade young children. Almost all children will get RSV before the age of 2. About 50% of children have had RSV infection twice or more.
Most children will have repeated infections in the next three years if they have been infected with RSV within one year of birth.
The virus detection rate of acute lower respiratory tract infection in children is related to age. Viral etiology of acute lower respiratory tract infection in children in my country from 2007 to 2010 showed that the virus detection rate of children with acute lower respiratory tract infection is 83.0% under 1 year old; 80.1% in the age old, and 60.8% in the age of 3 to 6 years old. The younger the age, the higher the virus detection rate.
RSV is the most common viral pathogen that causes severe pneumonia in children under 5 years old. A study on etiology of pneumonia in children's health (PERCH study) shows that RSV is the first pathogen of severe pneumonia in children, accounting for 51% of the viral pathogens, followed by rhinovirus, metapneumonia and influenza viruses.
3. RSV bullies the elderly and the young, and is more likely to infringe on children under 5
0 Just mentioned that RSV is the main pathogen of acute lower respiratory tract infection in children under 5 years old. In fact, People of all ages are generally susceptible to RSV, but young children and people over 60 years old are more likely to develop severe illness after infection.
"Expert Consensus on Diagnosis, Treatment and Prevention of Syncytial Virus Infection in Children" emphasizes:
. After RSV infection, the risk factors for developing acute lower respiratory tract infection include premature birth, low birth quality, males, siblings, mother smoking, a history of atopic dermatitis, non-breastfeeding and living environment, etc.;
. High-risk groups that develop into severe diseases include age 12 weeks, chronic lung diseases, congenital malformations, inconsistent throat function, left-to-right shunt congenital heart disease, Down syndrome, immunodeficiency and neuromuscular diseases, etc.
A US study on adult RSV infection showed that the elderly and patients with inherent diseases had a higher risk of severe infection, resulting in approximately 14,000 deaths in adult patients each year and approximately 177,000 hospitalizations in adult patients each year.
IV. RSV is prone to severe childhood
00 A study published in 2015 from the Global Epidemiological Surveillance Network shows that there are about 33.1 million new cases of acute lower respiratory tract infection caused by RSV in children under 5 years old, of which 3.2 million children need hospitalization (accounting for 28% of all acute lower respiratory tract infections), and 59,600 deaths in hospitalized children (accounting for 13%-22% of the deaths in acute lower respiratory tract infections).
It is estimated that the incidence rate of acute lower respiratory tract infection caused by RSV infection in my country is about 31.0‰, accounting for 18.7% of acute lower respiratory tract infections in children. has RSV detection rate among hospitalized children under the age of 2 from 2012 to 2015 in North China, including Beijing and Shandong, and has reached 33.3%, ranking first among viral pathogens; is based on research from 3 communities, and 40 people have RSV infections per 1,000 newborns per year, which is the main reason for neonatal hospitalization.
In addition to respiratory diseases, RSV infection can lead to other system lesions, such as cardiovascular system involvement, myocardial injury, right heart insufficiency, etc. A few studies have reported fatal interstitial myocarditis, severe heart rate arrhythmias and even heart failure after RSV infection. Central nervous system involvement may cause central apnea, epilepsy, RSV encephalopathy, RSV encephalitis, RSV meningitis, etc. In addition, very few cases may experience hypothermia, rash, thrombocytopenia and conjunctivitis.
5. The sequelae of RSV infection prolonged
Most children with RSV infection can fully recover without leaving any sequelae.
However, RSV infection during infancy and toddlers:
* More than 20% of children will experience recurrent wheezing, and more than 50% of children with recurrent wheezing experience recurrent wheezing.
* Lower respiratory infection of RSV in infancy is directly related to the occurrence of repeated wheezing and asthma, especially in children with a history of family allergies or atopic constitution.
* Children with RSV infection in infancy have 4 times the probability of developing asthma than healthy babies. In severe cases, lung function damage can last for more than 10 years. There are also reports that severe RSV infection in infancy is related to chronic obstructive pulmonary disease (COPD) in adults, but it is not yet confirmed whether this airway obstruction is caused by RSV infection or the specific constitution of the child.
6. The emergency medical treatment rate, hospitalization rate and mortality rate of infants and young children caused by RSV infection are higher than that of influenza
A study on the emergency medical treatment rate of children under 7 years old in the United States shows that:
html under 12 years old dose type 1 respiratory infection, the emergency medical treatment rate of children with RSV infection is three times that of influenza.
Another study of all age groups, a retrospective analysis of patients hospitalized for influenza and respiratory syncytial virus showed that the hospitalization rate of infants and young children under 11 years of age due to RSV infection was 16 times that of influenza; the mortality rate was 2.5 times that of influenza.
7. What should I do if my baby is infected with RSV?
If the baby has typical respiratory symptoms, including rapid respiratory rate, cough, wheezing, accompanied by irritability or difficulty in feeding, "three concave signs" appear when inhaling, etc., is recommended to seek medical treatment in time and follow the doctor's advice to diagnose and treat.
The key points of diagnosis include :
1, whether it is an epidemic season;
2, whether it has corresponding clinical symptoms and manifestations;
3, , a series of related laboratory tests and imaging examinations, including pathogenic examinations. Currently, the methods that can be used in clinical RSV diagnosis are mainly antigen detection and nucleic acid detection. Generally, nasopharyngeal swabs, pharyngeal swabs, nasopharyngeal aspirates, sputum, alveolar lavage fluid, etc. can be used for sample retention.
4, necessary imaging examinations, etc. There is currently no specific drug or effective preventive vaccine for
RSV infection. Major pharmaceutical companies around the world are working hard to carry out related new drug research. Among them, the most promising one to be launched is the -specific anti-RSV drug Ziresovir. Ziresovir is currently conducting phase III clinical trials of children and phase II clinical trials of adults around the world, which is expected to fill the gap in the antiviral field at home and abroad. Ziresovir is an RSV fusion protein inhibitor, which mainly acts on the virus during the binding and invasion stage of host cell. By affecting the allostericity of RSV fusion protein F, it blocks the virus from entering the host cell.
Tips: How to prevent respiratory virus infection
. When coughing and sneezing, cover your mouth and nose with a tissue or forearm, and do not have hands;
. Wash your hands frequently with soap and flowing water for 20 seconds;
. Avoid Don’t touch your face, eyes, nose and mouth with unwashed hands;
. Avoid close contact with people with cold symptoms, such as kissing, shaking hands, and do not share cups, tableware and toys with others;
. Clean and disinfect frequently-contact surfaces of objects such as door handles, tables and toys;
. Closely observe and evaluate the condition, and seek medical treatment in time when typical symptoms occur.
Main references:
1. Zhang Y, et al. J Glob Health. 2015;5(2):020417.
2. Jain S, et al. N Engl J Med. 2015;372(9):835-45.
3. Feng L, et al. PLoS One. 2014;9(6):e99419.
4, Régnier SA, et al. Pediatr Infect Dis J. 2013;32(8):820-826.
5. Madhi SA, et al. Clin Infect Dis. 2018;66(11):1658-1665.
6. Xie Z, et al. Chin J Appl Clin Pediatr.2020;35(4):241-250.
7. Pneumonia Etiology Research for Child Health (PERCH) StudyGroup. Lancet. 2019;394(10200):757-779.
8. Xie Z, et al. Chin J Pediatr. 2011;49(10):745-749.
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