Vector-borne viral diseases in horses

Vector-borne viral diseases are major threats to equine health worldwide. These infections are transmitted by arthropod vectors such as mosquitoes, biting midges, and horseflies, resulting in clinical manifestations ranging from mild febrile illness to severe neurological, respiratory, circulatory, or hematologic disorders with high mortality rates. Major equine vector-borne viral diseases include African horse sickness (AHS), equine infectious anemia (EIA), equine encephalomyelitis (Eastern: EEE, Western: WEE, and Venezuelan: VEE), West Nile virus (WNV), and Japanese encephalitis (JE). Each disease is caused by a distinct viral pathogen and transmitted by specific vectors that influence their epidemiology and geographic distribution. Transmission occurs through either biological replication within the vector or mechanical transfer via contaminated mouthparts, depending on the virus involved. Recent climate change, environmental alterations, and increasing international animal movement have contributed to the expansion of competent vectors and the emergence of these diseases in previously non-endemic regions. Effective prevention and control strategies rely on vaccination, vector control, surveillance, movement restriction, and early laboratory diagnosis. Cooperation among veterinary, vector, and environmental sectors is important for early outbreak detection and effective disease control.