Mosquito vector competence for Japanese encephalitis virus: a systematic review and meta-analysis update.

BACKGROUND

Japanese encephalitis is an emerging zoonotic disease caused by the Japanese encephalitis virus (JEV), transmitted primarily by mosquitoes of the Culex species. Amid the recent geographical expansion of JEV into Mainland Australia and the dramatic increase in research output, here we provide an update to our 2018 systematic review and meta-analysis, by appraising the scientific literature published from 2016 through 2023 and quantitatively summarizing the data from this update and the 2018 systematic review meta-analysis on vector competence for JEV.

METHODS

A systematic review of the literature on JEV vector and host competence, published from 2016 through 2023, was performed. Bibliographic databases, PubMed, Scopus, Web of Science, and the Armed Forces Pest Management Board website were searched for relevant literature. Records were screened for relevance for vector competence, specifically: infection rate, dissemination rate, and transmission rate. To estimate the overall and subgroup effect sizes for each mosquito species, random-effects meta-analysis models were utilized. Meta-regression models were fit to evaluate the association between a priori variables-such as mosquito subfamily/tribe, routes of JEV administration for mosquito infection, incubation length, incubation temperatures, and diagnostic methods for JEV detection-and the outcomes of interest.

RESULTS

This study update includes 74 new reports, identifying 9-12 additional mosquito species as competent for JEV, depending on the specific outcome assessed. The overall JEV infection, dissemination, and transmission rates across all species and studies were 45.4% (95% confidence interval (CI) 35.9-55.2%), 41.2% (95% CI 29.7-53.7%), and 22.7% (95% CI 14.6-33.4%), respectively. Among the subfamilies/tribes, Culicini had the highest infection (51.9%; 95% CI 39.2-64.4%) and transmission (27.8%; 95% CI 16.5-43.1%) rates. Meta-regressions showed mosquito subfamily/tribe was consistently associated with all the outcomes of interest, although the heterogeneity (I2) between studies remained consistently high (I2 > 83.47).

CONCLUSIONS

The information presented in this study provides a quantitative summary update on vector competence for JEV. Vector competence data are necessary for risk assessment models, the development of mosquito and virus surveillance programs, and effective prevention and control strategies in regions currently affected by JEV and those at risk of incursion.