Abstract
More than a million Japanese encephalitis (JE) cases occurred in mainland China from the 1960s to 1970s without vaccine interventions. The aim of this study is to analyze the spatial and temporal pattern of JE cases reported in mainland China from 1965 to 1973 in the absence of JE vaccination, and to discuss the impacts of climatic and geographical factors on JE during that period. Thus, the data of reported JE cases at provincial level and monthly precipitation and monthly mean temperature from 1963 to 1975 in mainland China were collected. Local Indicators of Spatial Association analysis was performed to identify spatial clusters at the province level. During that period, The epidemic peaked in 1966 and 1971 and the JE incidence reached up to 20.58/100000 and 20.92/100000, respectively. The endemic regions can be divided into three classes including high, medium, and low prevalence regions. Through spatial cluster analysis, JE epidemic hot spots were identified; most were located in the Yangtze River Plain which lies in the southeast of China. In addition, JE incidence was shown to vary among eight geomorphic units in China. Also, the JE incidence in the Loess Plateau and the North China Plain was showed to increase with the rise of temperature. Likewise, JE incidence in the Loess Plateau and the Yangtze River Plain was observed a same trend with the increase of rainfall. In conclusion, the JE cases clustered geographically during the epidemic period. Besides, the JE incidence was markedly higher on the plains than plateaus. These results may provide an insight into the epidemiological characteristics of JE in the absence of vaccine interventions and assist health authorities, both in China and potentially in Europe and Americas, in JE prevention and control strategies.
Highlights
Japanese encephalitis (JE) is an acute infectious zoonosis disease caused by infection with Japanese encephalitis virus (JEV) through mosquito bites [1,2,3,4,5]
These geomorphic units were as follows: the Qinghai-Tibet Plateau (QTP), which consists of Qinghai and Tibet; the Loess Plateau (LP) consisting of Shaanxi, Gansu, and Ningxia; the Inner Mongolian Plateau (IMP), which consists of the Inner Mongolian Autonomous Region; the Yunnan-Guizhou Plateau (YGP) consisting of Yunnan, Guizhou, and Sichuan; the Northeast China Plain (NECP), which consists of Heilongjiang, Jilin, and Liaoning; the North China Plain (NCP) covering Hebei, Beijing, Tianjin, Shanxi, Shandong, and Henan; the Yangtze River Plain (YRP), which consists of Hunan, Hubei, Anhui, Jiangsu, Jiangxi, Zhejiang, and Shanghai; and the Pearl River Delta Plain (PRDP), which mainly includes Guangdong province
Japanese encephalitis in mainland China in 1963–1975 There were more than 1.4 million reported JE cases in China from 1963 to 1975, accounting for almost 60% of the total reported JE cases since 1950
Summary
Japanese encephalitis (JE) is an acute infectious zoonosis disease caused by infection with Japanese encephalitis virus (JEV) through mosquito bites [1,2,3,4,5]. Infection results in damage to the central nervous system. Symptoms such as sustained high fever, disturbance of consciousness, and convulsions appear after infection with JEV, and the mortality rate can be more than 30%. JE is an internationally recognized public health problem and has been a cause for concern globally [3]. According to a report by the World Health Organization (WHO), ,69000 JE cases occur annually worldwide and JE is prevalent in 24 countries and territories in Asia and Oceania. 3000 million people live in the JE-endemic area and are at risk of JEV infection [2,3,8]
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