Epidemiology And Clinical Feateures Of Influenza A Virus And Swine-Qrigin Influenza A Virus Infection In Children With Respiratory Tract Infection In Chongqing

Objective:To discuss the prevalence, clinical characteristics of influenza A virus or swine-origin influenza A H1N1virus infection, and risk factors for the severity of influenza A virus infection in children with acute respiratory tract infection in Chongqing.Methods:From June2009to May2011,1074nasopharyngeal aspirates were collected in children with acute respiratory tract infection at Department of Respiratory Medicine in CHCMU. The RNA of IVA/S-OIVs in the sample was detected by RT-PCR technique. The RNA of positive sample was compared in GeneBank and summarize the clinical data of IVA/S-OIVs infection. The data was analyzed by SPSS17.0.Results:1. The detection rate of IVA/S-OIVs:1074specimens totally,105specimens was positive in IVA with the detection rate9.8%(15S-OIVs positive specimens is contained);15specimens was positive in S-OIVs with the detection rate1.4%.2. Epidemic characteristics:In105cases of IVA infection,72male and33female with the ratio of2.2:1, aged from1to135months.97cases (92.4%) happen in children≤5years old,with81cases (77.1%) positive in children≤2years old., which occurs mainly in spring and summer. In15cases of S-OIVs infection,12male and3females with the ratio of4:1, is aged from1to63months.13cases (86.7%) happen in children≤5years old,with12cases (80.0%) positive in children≤2years old., which occurs mainly in summer.3.3. Clinical characteristics:In the data, IVA/S-OIVs infection mainly caused pneumonia. Most of the cases had fever,cough,sputum,and1/3accompanied by wheezing. Pulmonary signs are mostly in moist rales.The IVA infection mixed the other common respiratory virus is in48samples (45.7%); the S-OIVs infection mixed the other common respiratory virus is in9samples (60.0%). The most common mixture is PIV3. WBC count was not heightened with lymphocyte classification-based usually.4.The risk factors of severe pneumonia related with IVA:,15children (14.3%) had Severe Pneumonia Of the105IVA infections,9males and6females. Klebsiella pneumoniae positive in sputum culture (P=0.023;OR=7.250;OR95%CI,1.311～40.098)or Congenital heart Diseases associated (P=0.010;OR=8.533;OR95%CI,1658～43.929)or the virus co-infection (P=0.027;OR=3.939;OR95%CI,1.164～13.329) increased the risk of severe pneumonia after IVA infection.Conclusion:1. IVA infection rate was9.8%in children with respiratory tract infection in Chongqing, the S-OIVs infection rate was1.4%. Children below2years is the major susceptible population with popular peak season in summer and spring.2.The clinical manifestations were not obviously specific after IVA/S-OIVs infection. The IVA co-infection rate with other common respiratory virus was45.7%, the S-OIVs co-infection was60%.The most common mixture is PIV3.3.The Klebsiella pneumoniae positive in sputum culture or Congenital heart diseases associated or the virus co-infection were the risk factors for the severe pneumonia related with IVA.