Article Abstract

Influenza surveillance in Jiangyin from 2013 to 2015

Authors: Cheng Qian, Xianwen Chen, Hengfu Cao, Minhua Gu, Yan Ma, Jianxiang Yao, Fangyan Shu

Abstract

Background: To understand the epidemiology of influenza in Jiangyin from 2013 to 2015, and to provide the scientific basis for the prevention and control of influenza.
Methods: Data concerning influenza-like illness (ILI) were gathered from two sentinel hospitals according to influenza surveillance. Descriptive epidemiology was applied to analyzing the epidemiology and etiology of influenza in Jiangyin from 2013 to 2015.
Results: A total of 927,656 cases were enrolled, of which 111,749 were ILI, the ILI % was 12.05% and showed a trend of decreasing year by year. Two seasonal peaks of ILI were observed in winter and summer each year. ILI cases was highest among children (1–14 years), especially in children aged <5 years. The age composition of ILI cases was significant different among different years (P<0.001). Type A (H3) and type B were the main influenza strains in the region. The proportion of influenza virus subtypes changed frequently between 2013 and 2015. The peak time of positive influenza cases were correspond to the peak time of ILI cases every year, and the etiology detection positive rate was positively correlated with ILI % (r=0.603, P=0.0001).
Conclusions: The ILI temporal trends can reflect the actual influenza activity in epidemic seasons. Thus, reinforcing surveillance of ILI in assembly occupancies were needed to prevent an outbreak of influenza. Simultaneously, vaccination is an effective way to protecting high-risk groups from influenza virus.