Serological and molecular epidemiology of Japanese Encephalitis in Zhejiang, China, 2015-2018

Abstract

Background Shifts have occurred in the epidemiological characteristics of Japanese encephalitis (JE), extending from the molecular level to the population level. The aim of this study was to investigate the seroprevalence of JE neutralizing antibodies in healthy populations from different age groups in Zhejiang Province, and to conduct mosquito monitoring to evaluate the infection rate of Japanese encephalitis virus (JEV) among vectors, as well as the molecular characteristics of the E gene of isolated JEV strains. Methodology/Principal findings A total of 1190 sera samples were screened by a microseroneutralization test, including 429 infants (28d-11m) and 761 participants (2y-82y). For those under 1 year old, the geometric mean titers (GMTs) of the JE neutralizing antibody was 9.49 at birth and significantly declined as the age of month increased (r =-0.225, P<0.001). For those above 1-year old, seropositive proportions were higher in subjects aged 1-3 years old as well as �25 years old (65%-75%), and relatively lower in subjects aged between 4-25 years old (22%-55%). Four or more years after the 2 nd dose of JEV-L (first dose administered at 8 months and the second at 2 years of age), the seropositive proportion decreased to 32.5%, and GMTs decreased to 8.08. A total of 87,201 mosquitoes were collected from livestock sheds in 6 surveillance sites during 2015-2018, from which 139 E gene sequences were successfully amplified. The annual infection rate according to bias-corrected maximum likelihood estimation of JEV in Culex tritaeniorhynchus was 1.56, 2.36, 5.65 and 1.77 per 1000, respectively. JEV strains isolated during 2015-2018 all belonged to Genotype I. The E gene of amplified 139 samples differed from the JEV-L vaccine strain at fourteen amino acid residues, including the eight key residues related to virulence and virus attenuation. No divergence was observed at the sites related to antigenicity. Conclusions/Significance Zhejiang Province was at a high risk of JE exposure due to relatively lower neutralizing antibody levels among the younger-aged population and higher infection rates of JEV in PLOS NEGLECTED TROPICAL DISEASES

Prevalence and Genetic Characteristics of Japanese Encephalitis Virus among Mosquitoes and Pigs in Hunan Province, China from 2019 to 2021

“…According to the genomic characteristics, JEV strains can be classified into five distinct genotypes (I, II, III, IV, and V). Among these, genotype III has been highly prevalent in past years in China, while current studies confirmed that the occurrences of JE in China were mainly caused by JEV genotype I strains [7,8].…”

Economic and disease burden of Japanese encephalitis in Zhejiang Province, 2013–2018

“…Type of occupation determines the wages of workday loss, which affects the indirect economic cost estimate. Although JE vaccine has been introduced in Zhejiang Province since 1953 [9], the coverage rate did not reach 90% until 2008. Therefore, most adult cases during 2013-2018 did not get vaccinated.…”

“…With the widespread use of JE vaccines, the rapid development of economy and remarkable improvement of sanitary conditions, the JE incidence had decreased sharply after the 1970s. However, recent epidemiological surveillance show that the incidence is on the rise due to global warming and improvement of diagnosis level, as well as report awareness [8,9]. The proportion of adult cases is increasing [8,9].…”

“…However, recent epidemiological surveillance show that the incidence is on the rise due to global warming and improvement of diagnosis level, as well as report awareness [8,9]. The proportion of adult cases is increasing [8,9]. JE usually peaks in July in Zhejiang Province.…”

The Comparison of Inflammatory Cytokines (IL-6 and IL-18) and Immune Cells in Japanese Encephalitis Patients With Different Progression

“…The incidence of JEV infection in children has decreased significantly since the launch of the nationwide JEV vaccination program in China in 2007 ( Deng et al., 2020 ). However, the number of adult/old patients infected with JEV has mounted recently due to the change of socio-environmental factors ( Zhang et al., 2018 ).…”