Emergence of equine herpes virus 1 myeloencephalopathy: a brief review

Abstract

Equine herpesvirus 1 (EHV1) is an economically important viral pathogen of equines and causes respiratory disease, neonatal foal mortality, late-term abortion and sporadic encephalomyelitis aka equine herpes myeloencephalopathy (EHM) in affected horses. The nervous form of EHV1 (EHM) has been recognized as early as 1950s in horse population; however, many aspects of this disease remained poorly understood. In recent years, there has been much progress in our understanding of genetics, epidemiology and pathogenesis of EHM through close monitoring of field outbreaks in different parts of the world. Various host, agent and environmental factors have been found to a play a role in the development of EHM, the most significant being the identification of a single nucleotide polymorphism in DNA polymerase gene (A2254 to G2254), which imparts neuropathogenic potential to the virus. EHM affects horses of all ages, including un-weaned foals and produces clinical symptoms that are indistinguishable from other viral encephalitis/ central nervous system (CNS) disorders. EHM treatment includes supportive therapy, and reducing inflammation of CNS. Diagnosis of affected horses and monitoring of in-contact animals is the best measures to prevent EHM outbreaks. This review in brief discusses about progress made in epidemiology, pathogenesis, treatment, prevention and control of EHM.