Seasonal Patterns of Japanese Encephalitis and Associated Meteorological Factors in Taiwan.

Che-Liang Lin,Hsiao-Ling Chang,Chuan-Yao Lin,Kow-Tong Chen

doi:10.3390/ijerph14111317

Abstract

The persistent transmission of Japanese encephalitis virus (JEV) in Taiwan necessitates exploring the risk factors of occurrence of Japanese encephalitis (JE). The purpose of this study was to assess the relationship between meteorological factors and the incidence of JE in Taiwan. We collected data for cases of JE reported to the Taiwan Centers for Disease Control (Taiwan CDC) from 2000 to 2014. Meteorological data were obtained from the Taiwan Central Weather Bureau. The relationships between weather variability and the incidence of JE in Taiwan were determined via Poisson regression analysis and a case-crossover methodology. During the 15-year study period, a total of 379 cases of JE were reported. The incidence of JE showed significant seasonality, with the majority of cases occurring in summertime (for oscillation, p < 0.001). The number of JE cases started to increase at temperatures of 22 °C (r2 = 0.88, p < 0.001). Similarly, the number of JE cases began to increase at a relative humidity of 70–74% (r2 = 0.75, p < 0.005). The number of JE cases was positively associated with mean temperature and relative humidity in the period preceding the infection. In conclusion, the occurrence of JE is significantly associated with increasing temperature and relative humidity in Taiwan. Therefore, these factors could be regarded as warning signals indicating the need to implement preventive measures.

Highlights

Japanese encephalitis (JE) is caused by the Japanese encephalitis virus (JEV).Japanese encephalitis virus, belonging to the Flaviviridae family, is transmitted by mosquitoes from animals to humans [1]
The illness spectrum of JE in humans ranges from asymptomatic infection to a devastating encephalitis syndrome that is associated with appreciable mortality and frequent central nervous system (CNS) sequelae in survivors [4]
Between January 2000 and December 2014, a total of 379 patients with JE were diagnosed by physicians in Taiwan

Summary

Introduction

Japanese encephalitis (JE) is caused by the Japanese encephalitis virus (JEV). Japanese encephalitis virus, belonging to the Flaviviridae family, is transmitted by mosquitoes from animals to humans [1]. The main transmission vectors of the JEV are Culex mosquitoes, Culex tritaeniorhynchus (Cx. tritaeniorhynchus), and the main vertebrate hosts for amplifying. JE is an important cause of viral encephalitis in most Asian countries, in South Asia, Southeast Asia, and East Asia [5,6]. Several countries in these regions have significantly reduced the morbidity of JE through several intervention measures, including early diagnosis, prompt treatment, national immunization, and effective vector control [7,8].

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