Bluetongue virus in Middle Eastern ruminants: vector evidence, surveillance gaps, and research priorities

Bluetongue virus (BTV) is an economically important arbovirus of domestic and wild ruminants transmitted primarily by Culicoides biting midges. The Middle East represents a key ecological corridor linking African, Asian, and European transmission systems, yet entomovirological evidence of BTV infection in regional Culicoides populations remains fragmented. This narrative review synthesizes available literature on Culicoides species distribution and published evidence of BTV detection in field-collected midges across Middle Eastern countries. Major bibliographic databases were searched to identify entomological surveys, entomovirological investigations, and ecological studies relevant to BTV transmission in livestock-associated settings. Published data indicate that several proven or suspected vector species, including Culicoides imicola, members of the Obsoletus and Pulicaris groups, and other candidate vectors, are widely distributed across the region. However, although serological and clinical evidence confirms BTV circulation in ruminant populations in multiple countries, direct detection of BTV in Culicoides has been reported only in a limited number of settings. Most countries rely primarily on animal-based surveillance, with limited integration of systematic vector monitoring. Methodological heterogeneity, short-term sampling, and restricted use of sensitive molecular diagnostics likely contribute to under-detection of infected midges. Strengthening bluetongue preparedness in the Middle East requires coordinated, longitudinal Culicoides surveillance combined with standardized molecular screening, improved taxonomic resolution, and integration of vector and host data to better define transmission dynamics and support evidence-based control strategies in livestock production systems.