Prevalence of West Nile Virus in Zoonotic Animal Species in Asia (2000–2024): A Systematic Review and Meta-Analysis

Abstract

West Nile virus (WNV), a mosquito-borne pathogen causing encephalomyelitis in animals, is an emerging health concern in Asia. Despite its public and veterinary health significance, data on WNV prevalence remain scarce in countries such as Cambodia, Kazakhstan, Pakistan, and Singapore, with only isolated or zero-prevalence reports. This systematic review and meta-analysis aimed to assess the prevalence of WNV in various animal species across Asia from 2000 to 2024. A comprehensive search of PubMed (n = 636), Web of Science (n = 364), and Google Scholar (n = 542) was conducted using predefined keywords and strict inclusion criteria. Out of 1,542 records screened, 38 studies met the criteria for final analysis, encompassing 93,268 animals, including equines, bovines, small ruminants, swine, poultry, felines, canines, and wild birds. The overall estimated prevalence of WNV in animals was 7.52%. Prevalence varied across studies, influenced by differences in sampling strategies, diagnostic methods, and host species. Temporal analysis revealed fluctuating prevalence trends over the two decades, some aligning with documented WNV outbreaks. Study heterogeneity was associated with variability in geographical coverage, study designs, and ecological factors. Climate change, vector abundance, and migratory bird routes were identified as potential factors contributing to the spread of WNV. Risk factors included (i) ecological intensity (wetlands, irrigated lands), (ii) climatic factors (temperature, rainfall), (iii) vector abundance (Culex spp. density), and (iv) migratory bird flyways. These findings highlight the need for standardised surveillance systems and coordinated monitoring across the region. Enhanced vector control, systematic reporting, and increased research efforts are vital for mitigating WNV risks. Strengthening intersectoral collaboration between veterinary and public health services is essential for effective disease control and prevention. This study provides a foundation for improved understanding of WNV transmission dynamics and supports evidence-based strategies for managing this growing zoonotic threat in Asia.