Recurrence of Japanese Encephalitis Epidemic in Wuhan, China, 2009–2010

Quan Hu,Junhua Tian,Yu Zhou,Xiaoyong Zhang,Xin Zheng,Banghua Chen,Zerong Zhu,Young-Min Lee

doi:10.1371/journal.pone.0052687

Abstract

BackgroundJapanese encephalitis (JE) was once epidemic in most areas of China, including Wuhan, a city located in the central part of China. The incidence of JE dramatically decreased due to nationwide immunization with the live attenuated JE virus (JEV) vaccine, and no JE cases were reported during 2005–2008 in Wuhan. In 2009 and 2010, 31 JE cases reoccurred in this area. In this study, we investigated the causes of JE recurrence.Methods and FindingsAll JE cases were laboratory-confirmed by detecting the JEV-specific IgM antibody with an IgM-capture enzyme-linked immunosorbent assay (ELISA). All patients were children between 2 months and 9 years of age with a median age of 2 years. Of the 31 cases, 9 had received one or two doses of the JEV vaccine, 11 had not been immunized previously with the JEV vaccine, and 11 had an unclear immunization history. Through reverse transcription polymerase chain reaction (RT-PCR), sequencing, and phylogenetic analysis, two new strains of JEV were isolated from Culex tritaeniorhynchus and identified as genotype 1 JEV, rather than genotype 3, which circulated in this area previously.ConclusionsVaccine failure or missed vaccination may have caused JE recurrence. Local centers for disease control and prevention need to improve immunization coverage, and the efficacy of the JE vaccine needs to be reevaluated in a population at risk for disease.

Highlights

Local centers for disease control and prevention need to improve immunization coverage, and the efficacy of the Japanese encephalitis (JE) vaccine needs to be reevaluated in a population at risk for disease
Japanese encephalitis (JE) is an acute epidemic disease of the central nervous system caused by infection with the Japanese encephalitis virus (JEV), which primarily affects children and adolescents [1,2]
Subjects In 2009 and 2010, all suspected JE cases reported to the Chinese Disease Reporting Information System (CDRIS) in Wuhan were further investigated by the Wuhan Centers for Disease Control and Prevention (CDC) according to a WHOrecommended JE surveillance project [20]

Summary

Methods and Findings

All JE cases were laboratory-confirmed by detecting the JEV-specific IgM antibody with an IgMcapture enzyme-linked immunosorbent assay (ELISA). All patients were children between 2 months and 9 years of age with a median age of 2 years. Of the 31 cases, 9 had received one or two doses of the JEV vaccine, 11 had not been immunized previously with the JEV vaccine, and 11 had an unclear immunization history. Through reverse transcription polymerase chain reaction (RT-PCR), sequencing, and phylogenetic analysis, two new strains of JEV were isolated from Culex tritaeniorhynchus and identified as genotype 1 JEV, rather than genotype 3, which circulated in this area previously

Introduction

Materials and Methods

Results

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