Comprehensive review of emerging insights into bluetongue virus in small ruminants with emphasis on epidemiology, diagnosis and control in Bangladesh and South Asia

Abstract Bluetongue (BT) is a vector-borne, non-contagious, and infectious viral disease affecting domestic and wild ruminants, caused by the Bluetongue virus (BTV), a member of the genus Orbivirus in the family Sedoreoviridae . The disease primarily affects sheep, goats, and cattle, with sheep being the most susceptible species. BTV is transmitted by Culicoides biting midges and can cause severe clinical manifestations, including fever, facial and limb edema, oral lesions, lameness, and tongue cyanosis. The disease is associated with significant economic losses due to mortality, reduced production, trade restrictions, and costs related to control and prevention. Morbidity and mortality rates vary widely depending on the species, breed susceptibility, and environmental conditions. Effective control strategies include vector management, movement restrictions, and vaccination programs. While BT has been widely reported in many parts of the world, its presence in Bangladesh has not been fully understood until recent years. New studies have confirmed the circulation of BTV antibodies in small ruminants and, more recently, the molecular detection of the virus itself. This comprehensive review presents an in-depth synthesis of the epidemiology, clinical presentation, diagnostic methods, and control strategies for BT, with special emphasis on Bangladesh and the South Asian context. This review also highlights recent research findings, available diagnostic approaches, and vaccine options, while identifying critical knowledge gaps that need to be addressed to improve disease surveillance and control in the region.