The Spatio-temporal Distribution of Japanese Encephalitis Cases in Different Age Groups in Mainland China, 2004 - 2014.

Xiaolong Li,Wenwen Lei,Guodong Liang,Ying He,Bin Wang,Xiaoqing Lu,Huanyu Wang,Xiaoyan Gao,Miao Song,Minghua Li,Shiheng Cui,Zhi Lv,Shihong Fu,Mark L Wilson

doi:10.1371/journal.pntd.0004611

Abstract

BackgroundJapanese encephalitis (JE) is very prevalent in China, but the incidence of JE among children has been greatly reduced by extensive promotion of vaccinations. The incidence of JE among adults, however, has increased in some parts of China.Methods/Principal FindingsData on JE in mainland China, in terms of incidence, gender, and age, were collected between 2004 and 2014. We conducted spatial and temporal analyses on data from different age groups. Generally, children aged 0–15 years still represent the major population of JE cases in China, despite the gradual decrease in incidence over years. However, the incidence of JE among adults in several provinces is notably higher than the national average, especially during the epidemic waves in 2006, 2009, and 2013. The JE cases in the 0–15-year-old group are distributed mainly in the area south of the Yangtze River, with peak incidence occurring from July to September. In the adult group, especially for those over 40 years old, the JE cases are concentrated mainly in the area north of the Yangtze River. JE incidence in the adult group in September and October is significantly greater compared to the other groups. Further analysis using Local Indicators of Spatial Association (LISA) reveals that the distribution of adult JE cases in the six provinces north of the Yangtze River, between north 30–35° latitude and east 110–130° longitude, is a hotspot for adult JE cases.Conclusions/SignificanceThe rate of JE case increase for adults is much greater than for children and has become a public health issue. Therefore, studies on the necessity and feasibility of vaccinating adults who live in JE-endemic areas, but have never been vaccinated for JE, should become a new focus of JE prevention in the future.

Highlights

Japanese encephalitis (JE) is a viral disease transmitted by mosquitoes which can lead to severe viral encephalitis
It is well known that children are the population most susceptible to Japanese encephalitis (JE), and the incidence of JE among children in China has been greatly reduced by extensive promotion of vaccinations aiming at children
We explore and describe the spatial and temporal distribution of JE cases observed among different agegroups in China from 2004 to 2014

Summary

Introduction

Japanese encephalitis (JE) is a viral disease transmitted by mosquitoes which can lead to severe viral encephalitis. As a mosquito-borne disease, JEV can be carried by varied mosquito species, such as Culex, Anopheles, Aedes and so on. Among these species, Culex tritaeniorhynchus is the principle vector of JEV; other mosquitoes of the genus Culex like Culex annulirostris, Culex vishnui Theobald, Culex bitaeniorhynchus Giles, and Culex pipiens Linnaeus can act as the vector. Human beings, especially those living near the rice fields becomes more exposed to the mosquitoes, which greatly increases the risk of JEV infection. Pigs, both domestic and wild pigs, are the major reservoirs serving as the hosts of virus amplification during the enzootic cycle of JEV transmission. The incidence of JE among adults, has increased in some parts of China

Objectives

Methods

Results

Discussion

Conclusion