Spatiotemporal Patterns of Japanese Encephalitis in China, 2002–2010

Li-Ya Wang,Yi-Xing Li,Hai-Long Sun,Wen-Wu Yin,Archie C A Clements,Wen Zou,Peng Bi,Shen-Long Li,Wen-Yi Zhang,Qi-Yong Liu,Fan Ding,Wen-Biao Hu,Liu-Yu Huang,Ricardo J Soares Magalhaes,Yong Wang,Cheng-Yi Li

doi:10.1371/journal.pntd.0002285

Abstract

ObjectiveThe aim of the study is to examine the spatiotemporal pattern of Japanese Encephalitis (JE) in mainland China during 2002–2010. Specific objectives of the study were to quantify the temporal variation in incidence of JE cases, to determine if clustering of JE cases exists, to detect high risk spatiotemporal clusters of JE cases and to provide evidence-based preventive suggestions to relevant stakeholders.MethodsMonthly JE cases at the county level in mainland China during 2002–2010 were obtained from the China Information System for Diseases Control and Prevention (CISDCP). For the purpose of the analysis, JE case counts for nine years were aggregated into four temporal periods (2002; 2003–2005; 2006; and 2007–2010). Local Indicators of Spatial Association and spatial scan statistics were performed to detect and evaluate local high risk space-time clusters.ResultsJE incidence showed a decreasing trend from 2002 to 2005 but peaked in 2006, then fluctuated over the study period. Spatial cluster analysis detected high value clusters, mainly located in Southwestern China. Similarly, we identified a primary spatiotemporal cluster of JE in Southwestern China between July and August, with the geographical range of JE transmission increasing over the past years.ConclusionJE in China is geographically clustered and its spatial extent dynamically changed during the last nine years in mainland China. This indicates that risk factors for JE infection are likely to be spatially heterogeneous. The results may assist national and local health authorities in the development/refinement of a better preventive strategy and increase the effectiveness of public health interventions against JE transmission.

Highlights

Japanese encephalitis (JE) is a mosquito-borne disease, which primarily occurs in rural and suburban areas of Southeast Asia and the Western Pacific region [1,2,3]
JE cases present a wide spectrum of clinical manifestations, which vary from non-specific febrile flu-like illness to severe clinical manifestations including behavioral abnormality, alteration in sensorium and respiratory paralysis [7]
The primary spatiotemporal cluster of JE was detected in Southwestern China between July and August, with the geographical range of JE transmission increasing over the past years

Summary

Introduction

Japanese encephalitis (JE) is a mosquito-borne disease, which primarily occurs in rural and suburban areas of Southeast Asia and the Western Pacific region [1,2,3]. Japanese encephalitis virus (JEV) is transmitted in an enzootic cycle among mosquitoes and vertebrate amplifying hosts, primarily in domestic pigs and ardeid birds naturally [4]. Primarily Culex tritaeniorhynchus, are abundant in rural areas where their larvae breed in rice paddies and pools of stagnant water. A recent literature review estimated that annually a total of 68,000 JE cases are reported worldwide [6]. JE cases present a wide spectrum of clinical manifestations, which vary from non-specific febrile flu-like illness to severe clinical manifestations including behavioral abnormality, alteration in sensorium and respiratory paralysis [7]

Methods

Results

Discussion

Conclusion