Study Of RSV Detection Rate, Viral Load, Clinical Features And Follow-up In Outpatient Children With Acute Lower Respiratory Infection

Part?Analysis RSV detection rate,viral load,clinical characteristics and follow-up of 457 outpatient children with acute lower respiratory infectionObjective:RSV is one of the most common viral pathogens of acute lower respiratory infections(ALRI)in infants and is also the main cause of hospitalized infants.with ALRI.Studies have shown that early RSV infection is associated with recurrent wheezing and the development of asthma.The viral load of severe RSV infection is related to severity of disease.We aim to compare clinical characteristics of ALRI with single RSV-detected,other virus-detected and the-undetected,to analyze the correlation between RSV load and clinical scores,to follow up the outcome of the single RSV-detected children and the case of wheezing again or recurrent wheezing in asthmatic children with Bronchilitis after RSV infection in outpatient department.Methods:Collect the nasopharyngeal aspirates(NPAs)during half a year(from October 2016 to March 2017)from outpatient infants under two years old who were diagnosed with ALRI.PCR methods were applied to detect common respiratory viruses.QPCR method was used to detect the viral load.Clinical features of patients with single RSV-detected,other virus-detected and the-undetected were compared.The relationship of RSV load and clinical scores was analyzed.Follow-up by telephone was carried out to investigate the outcome of the single RSV-detected children and the incidence of wheezing again or recurrent wheezing after RSV infection.Results:A total of 457 infants were recruited and 400 of them(87.5%)were tested positive for viruses.Thereinto,the single RSV-positive was 271(59.3%),other virus was 75(16.4%)and the undetected was 57(12.5%).Compared with the latter two groups,the single RSV-detected infants were more likely to show the symptoms of fever,wheezing and dyspnea(P<0.05).57.9%of RSV-detected children were in 6 months.There was no significant correlation between RSV load and clinical scores(r~2=0.0012,P>0.05).The hospitalized children with single RSV-detected were 29(11.4%).Their age was significantly younger than that of those who were not hospitalized(P=0.001).Logistic analysis showed that age(P=0.002)was a protective factor and premature(P=0.037)was a risk for the single RSV-detected children with ALRI.A follow-up study of children with bronchiolitis found:the single RSV-positive patients with bronchiolitis had a higher incidence of wheezing again and recurrent wheezing(25.9%and 15.8%,respectively).It was found that preterm was one of the risk factors for recurrent wheezing of children with bronchiolitis at the single RSV-positive group by logistic regression analysis(P=0.035).Conclusion:Infants younger than 6 months are likely to have RSV infections in winter and spring.The disease severity of the RSV-detected infants is heavier,and the likelihood of the children's later wheezing or recurrent wheezing is higher.The younger,the hospitalization rate is higher.Younger and premature are risk factors for the hospitalization of RSV associated ALRI.Preterm is one of the risk factors for children's recurrent wheezing in a shot-term after RSV bronchiolitis in infants.Part? Assessment of the correlation between viral load and clinical severity in hospitalized infants with RSV-ALRIObjective: RSV is believed to be one of the most important viral pathogens causing ALRI in children.It's reported that RSV load is related to the disease severity of hospitalized children with ALRI,but it's controversial.The purpose of this study was to investigate the correlation of dynamic RSV load and ALRI severity and to study the situation of wheezing again after early severe RSV-infection.Methods: According to the strict inclusion criteria,recruiting infants younger than 24 months with ALRI in October 2016 to March 2017 and collecting the NPAs at the specified time point.16 common respiratory viruses were detected by PCR and the viral load of RSV positive specimens were detected by QPCR.A telephone follow-up study was conducted for the enrolled children.Results: 38 cases of RSV-ALRI infants were enrolled,and 163 NPAs were collected.In hospitalized children,mainly male(81.1%),the ratio of males and females was 4.29:1,the median age was smaller(2 months),and the length of hospitalized days was four to eleven.Furthermore,there was a weak positive correlation(r2=0.2787,P<0.0001)between RSV viral load and the severity of disease.RSV load decreased with increasing time,and the peak viral load was observed on the first day of admission.With increasing of the hospital stay,the viral load decreased significantly and the clinical symptoms improved markedly.The rate of wheezing again in hospitalized children was 33.3%,and one third of them had recurrent wheezing.Conclusion: Male and young infants are more vulnerable to severe RSV infections,especially younger.The viral load and dynamic changes of severe RSV infection are related to the severity of the disease.Follow-up shows that these children who suffered early RSV-bronchiolitis have a higher incidence of wheezing again.