Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
United States Department of Agriculture-Agricultural Research Service (USDA-ARS) Arthropod-Borne Animal Diseases Research, 1515 College Ave., Manhattan, KS, USA.
Parasit Vectors. 2017 Sep 7;10(1):418. doi: 10.1186/s13071-017-2354-7.
Japanese encephalitis (JE) is a zoonosis in Southeast Asia vectored by mosquitoes infected with the Japanese encephalitis virus (JEV). Japanese encephalitis is considered an emerging exotic infectious disease with potential for introduction in currently JEV-free countries. Pigs and ardeid birds are reservoir hosts and play a major role on the transmission dynamics of the disease. The objective of the study was to quantitatively summarize the proportion of JEV infection in vectors and vertebrate hosts from data pertaining to observational studies obtained in a systematic review of the literature on vector and host competence for JEV, using meta-analyses.
Data gathered in this study pertained to three outcomes: proportion of JEV infection in vectors, proportion of JEV infection in vertebrate hosts, and minimum infection rate (MIR) in vectors. Random-effects subgroup meta-analysis models were fitted by species (mosquito or vertebrate host species) to estimate pooled summary measures, as well as to compute the variance between studies. Meta-regression models were fitted to assess the association between different predictors and the outcomes of interest and to identify sources of heterogeneity among studies. Predictors included in all models were mosquito/vertebrate host species, diagnostic methods, mosquito capture methods, season, country/region, age category, and number of mosquitos per pool.
Mosquito species, diagnostic method, country, and capture method represented important sources of heterogeneity associated with the proportion of JEV infection; host species and region were considered sources of heterogeneity associated with the proportion of JEV infection in hosts; and diagnostic and mosquito capture methods were deemed important contributors of heterogeneity for the MIR outcome.
Our findings provide reference pooled summary estimates of vector competence for JEV for some mosquito species, as well as of sources of variability for these outcomes. Moreover, this work provides useful guidelines when interpreting vector and host infection proportions or prevalence from observational studies, and contributes to further our understanding of vector and vertebrate host competence for JEV, elucidating information on the relative importance of vectors and hosts on JEV introduction and transmission.
日本脑炎（JE）是一种在东南亚由感染日本脑炎病毒（JEV）的蚊子传播的动物传染病。日本脑炎被认为是一种具有潜在传入目前无 JEV 国家的新兴外来传染病。猪和鹳形目鸟类是该病的储存宿主，在疾病的传播动态中起着重要作用。本研究的目的是使用荟萃分析定量总结文献系统评价中有关媒介和宿主对 JEV 易感性的观察研究中获得的数据中媒介和脊椎动物宿主中 JEV 感染的比例。
本研究中收集的数据涉及三个结果：媒介中 JEV 感染的比例、脊椎动物宿主中 JEV 感染的比例和媒介中的最小感染率（MIR）。按蚊或脊椎动物宿主物种进行随机效应亚组荟萃分析模型拟合，以估计汇总指标，并计算研究之间的方差。拟合元回归模型以评估不同预测因子与感兴趣结局之间的关联，并确定研究之间异质性的来源。纳入所有模型的预测因子包括蚊/脊椎动物宿主物种、诊断方法、蚊子捕获方法、季节、国家/地区、年龄类别和每个池中的蚊子数量。
蚊种、诊断方法、国家和捕获方法是与 JEV 感染比例相关的重要异质性来源；宿主物种和地区被认为是与宿主中 JEV 感染比例相关的异质性来源；诊断和蚊子捕获方法被认为是 MIR 结果异质性的重要贡献者。
我们的研究结果为某些蚊种的 JEV 媒介易感性提供了参考汇总估计值，以及这些结果的可变性来源。此外，这一工作为解释观察性研究中的媒介和宿主感染比例或流行率提供了有用的指导，并有助于进一步了解 JEV 的媒介和脊椎动物宿主易感性，阐明了有关媒介和宿主在 JEV 传入和传播中的相对重要性的信息。
