Study on the relations between epidemiology of respiratory syncytial infection in children and climate factors in Hangzhou

Objective To study the epidemiolgy of respiratory syncytial virus(RSV) infection in children and its relations to climate factors in Hangzhou. Methods Monthly positive rate of RSV in pneumonia inpatients and climate factor including mean air temperature, mean relative humidity and rainy days per month were continuously observed for 3 years. Correlation analysis for RSV positive rate and these three climate factors were performed using partial correlation, and regression methods between the positive rate and significant factor was done. Results 13 642cases were detected and 25.8% showed positive of RSV. The positive rate of RSV in children ≤1 years old, 1-3 years old, 3 years old were 33.1%, 19.7% and 5.1% respectively with significant difference( χ2= 763.7, P= 0.000). Rate of RSV infection was increased from December and kept in high level until May or April next year, but were varied at different years. Partial correlations between positive rate and rainy days, mean relative humidity, and mean air temperature per month were 0.32( P= 0.066), -0.27( P= 0.117) and -0.83( P= 0.000) respectively. The regression equation of RSV positive rate and mean air temperature was:RSV positive rate(%)= 52.933- 1.914×mean air temperature(℃). Conclusion RSV was one of the main factors causing of pneumonia in children while the highest infectious rate was in children ≤1 year old and infectious rate reduced along with the increase of age. Low air temperature was the main factor affecting the epidemiology of RSV. RSV was prevalent both in spring and winter in Hangzhou area.