Epidemiological Characteristics Of Respiratory Syncytial Virus Infection In Children In Hangzhou

【BACKGROUND】Respiratory syncytial virus(RSV) is a major cause of lower respiratory tract infections(LRTIs).Meteorologic factors could affect the prevalence of RSV.【OBJECTIVE】To obtain epidemiologic characteristics of RSV about age,gender and season differences from 2001 to 2006.To study Correlation between RSV positive rate and meteorologic factors.【METHODS】1.Study subjects were pediatric inpatients with lower respiratory tract infections from Jan.2001 to Dec.2006 in The Children's Hospital Zhejiang University School of Medicine.RSV antigen in nasopharyngeal secretions were tested with direct immunofluorescence.2.Meteorologic data from 2001 to 2006,including average monthly temperature, average monthly relative humidity and monthly rainy days were provided by Hangzhou Weather Bureau. 3.Outcome measures:RSV infection rate among different age groups;RSV infection rate between both genders;correlation between RSV infection rate and meteorologic factors;RSV infection rate among seasons;RSV infection rate among years.4.Statistical management:Data were statistically described and analyzed by SAS 8.2 software.Cochran-Mantel-Haenszel(CMH) method and partitions of x~2 method were used for analysis of the data.【RESULTS】1.Gender and age distributionRSV positive rate was 21.86%in all patients.Among them,the positive rate of under 1 year group was 30.99%,1-to 3- year-old group was 14.84%and older than 3 years group was 3.93%.Between under 1 year group and 1- to 3- year-old group,and between 1- to 3- year-old group and older than 3 years group,both statistic significance existed,with p＜0.001.The positive rate of males was 22.76%,and females was 20.24%, also showing statistical significance(P＜0.01).2.Meteorologic factorsCorrelation analysis between RSV positive rate and meteorologic factors showed strong correlation(correlation coefficient(R)=-0.838,(p＜0.01) between RSV positive rate and average monthly temperature.RSV positive rate dropped 1.837%with temperature hoisted every 1℃.There were no correlation between RSV positive rate and monthly rainy days(R=-0.034,p＞0.05),neither with average monthly relative humidity(R＝0.079,p＞0.05).3.Seasonal and annual distributionRSV positive rate in winter(41.89%) was much higher than spring(23.54%), autumn(8.53%) and summer(1.41%).Between each season:winter and spring,spring and autumn,autumn and summer,all having statistical significance with p＜0.001.In winters between each year,RSV positive rate in 2005(24.50%) was lower than 2002 (32.82%),2003(30.01%),2004(30.25%) and 2006(31.20%),all having statistic significance with p＜0.001.In springs,RSV positive rate in 2002 and 2003 was higher than 2001(11.73%),2004(18.35%),2005(18.27%),and 2006(15.27%),all having statistic significance with p＜0.001.【Conclusion】1 RSV is the major viral pathogen in LRTIs among young children.2 The younger the more vulnerable to RSV infection,especially infants;boys are more apt to RSV infection than girls.3 RSV positive rate and average monthly temperature were negatively correlated. The lower the temperature,the higher the infection rate.No correlation was revealed between RSV positive rate and monthly rainy days or average monthly relative humidity.4 RSV infection rate peaked in winter and spring,but variesed every year.