Objectives To investigate the epidemiological feature of respiratory syncytial virus (RSV) in hospitalized children with acute respiratory infection. Methods A total of 28 871 children with acute respiratory tract infection from Janu-ary 2007 to December 2011 were enrolled in the study. Nasopharyngeal aspirates were obtained from the respiratory tract by aseptic vacuum aspiration. Direct immuno-lfuorescence assay was used to detect RSV antigen. Correlation between RSV posi-tive rate and meteorological data including mean air temperature and total monthly rainfall, etc. was analyzed. Results The peak infection seasons of RSV during 2007-2010 were winter and spring in Suzhou, while in 2011 the infection rate of RSV was increased since July. The positive rates of RSV during winter and spring in 2007-2008, 2008-2009, 2009-2010 and 2010-2011 were 38.57%, 19.86%, 29.73%and 30.79%, respectively, with signiifcant difference (χ2=176.85, P<0.001). From July to September in 2011, the positive rate of RSV was 5.74%, 21.09%and 31.15%, respectively, higher than that of the same period from 2007 to 2010 (χ2=8.06~405.43, all P<0.05). The positive rate of RSV was negatively correlated with mean temperature, volume of rainfall, duration of sunshine and wind velocity (r=-0.799~-0.214, all P<0.05). Only mean temperature had a signiifcant impact on RSV activity by a stepwise multiple regression (P<0.001). Conclusions The date indicated that RSV was still an important etiological agent for acute lower respiratory infection in infants and young children in Suzhou area during winter and spring. The incidence of RSV was associated with the climate in Suzhou.

Objective To explore the epidemiology of different subgroups of respiratory syncytial virus (RSV) in hospi-talized children with acute respiratory infections in Suzhou. Methods RSV antigen in nasopharyngeal secretions specimens ob-tained from 42 208 hospitalized children with acute respiratory infections from January 2006 to December 2012 were detected using direct immunofluorescence assay. RT-PCR was used to differentiate subgroups A and B of RSV from the positive samples which were randomly selected in the epidemic season of different years. Results RSV infection had a seasonal trend. The peak season of RSV occurred between November and following year’s March and the detection rate of RSV was low between May and September. There was difference in RSV positive rates of peak seasons among different years from 2006 to 2012 (χ2=280.09,P<0.01). In 398 RSV antigen positive samples obtained from peak seasons of different years, 80.15%(319/398) were differentiated as subgroup A and 15.83%(63/398) were subgroup B except 16 samples (4.02%). There was significant difference in distribution of RSV subgroups in peak seasons among different years (P<0.01). Subgroup A of RSV was prevalent in most years. Both subgroup A and B were prevalent in peak season of 2008~2009 with lowest positive rate of RSV. In 2009~2010, subgroup B was prevalent. Conclusions From 2006 to 2012 in Suzhou area, the RSV detection rates in the first four prevalent seasons present an increase trend every other year and then sustain a high prevalence in the following two prevalent seasons. Subgroup A of RSV was the predominant pathogen in hospitalized children with acute respiratory infections.

OBJECTIVETo study the application of serodiagnosis of human bocavirus (HBoV) lower respiratory tract infection in children.

METHODFrom January to April, 2013, samples including serum, sputum and bronchoalveolar lavage fluids (BALFs) were obtained from 714 children hospitalized with ALRI. Serums were tested for HBoV-specific IgG and IgM antibodies by ELISA and all kinds of samples were tested for HBoV DNA by quantitative real-time fluorescent PCR. The results of HBoV serologic tests, viral DNA in sputum and their combination were compared with those of HBoV DNA in serums and/or BALFs, which was considered as the "standard". Their consistence and differences were evaluated, and the diagnostic parameters including sensitivity, specificity, positive predictive value, negative predictive value, consistency rate, Kappa value and J value were calculated. Age distributions of the HBoV positive patients tested by the latter two methods were also compared.

RESULTThe positive rate of HBoV serology was 13.2% (94/714) . The results of HBoV serology, its DNA in sputum and their combination were all consistent with those of HBoV DNA in serums and/or BALFs (χ(2) = 91.834, 124.662, 138.643, P < 0.001 for all comparisons) . Differences were significant by McNemar test (χ(2) = 23.547, 33.440, 12.410, P all <0.001) . All the diagnostic parameters for single HBoV serologic test or single viral DNA test in sputa were approximate. However, they were improved to 70.4%, 94.8%, 38.0%, 98.6%, 93.7%, 0.463(P < 0.001), 0.65 for sensitivity, specificity, positive predictive value, negative predictive value, consistency rate, Kappa value and J value, respectively, when the methods were combined. HBoV was found positive mainly in children under 3 years of age, especially in the 1 year group. The positive rates were the highest in both group -1 year, and group -3 years was the next. However, the rate was the lowest in group >3 years and in the group -6 months.

CONCLUSIONDiagnostic power can be improved and age distribution can be demonstrated when serologic tests were combined with traditional sputum DNA detection in children with HBoV lower respiratory tract infection.

Acute Disease ; Adolescent ; Age Distribution ; Antibodies, Viral ; analysis ; blood ; Antigens, Viral ; analysis ; Child ; Child, Preschool ; Enzyme-Linked Immunosorbent Assay ; Female ; Human bocavirus ; genetics ; isolation & purification ; Humans ; Immunoglobulin G ; blood ; Immunoglobulin M ; blood ; Infant ; Male ; Parvoviridae Infections ; diagnosis ; virology ; Real-Time Polymerase Chain Reaction ; Respiratory Tract Infections ; diagnosis ; virology ; Sensitivity and Specificity