Equine herpesvirus-1 infection, clinical features, treatment and control

Abstract

Equine herpesvirus type 1 (EHV-1) is a worldwide threaten affects the equine industry. The clinical features of EHV-1 infection included the respiratory, abortion, neonatal disease, and neurological forms with a frequently fatal outcome especially in the old age cases. The respiratory form characterized by fever, anorexia and nasal discharges. The abortion could occur in the last third of pregnancy either sporadically or progress into a storm. While in the case of myelencephalopathy, the signs ranged from mild ataxia to severe neurological deficits. Treatment of such cases depends on decreasing the inflammatory signs through using symptomatic and supportive treatment. So, a combination of free-radical scavengers, anticoagulants, and anti-inflammatory drugs, specific anti-herpesvirus drugs (e.g. acyclovir and valacyclovir) especially with the injection route rather the oral one are recommended. Because of the ubiquitous nature of the EHV-1 and the establishment of lifelong latency, elimination of the pathogen from the equine population is difficult. EHV-1 infection results in short-lived immunity which does not prevent re-infection. Although the modified live virus (MLV) and inactivated vaccines are available, it was shown to suppress EHV-1 disease not to limit the viral load. The MLV vaccines have an excellent safety record and can protect horses against clinical disease; however, their efficacy in preventing viremia, abortion, and neurological disease is unclear. Early diagnosis, prevention of further spread and management of clinical cases are the major priorities to control an outbreak. Prevention of virus spreading can be relatively achieved through sound biosecurity measures. This entails quarantine and isolation of new additions for at least a month, cleaning and disinfection of transportation equipment, fomites, and the areas contaminated using disinfectants like chlorine, the quaternary ammonium compounds and the sodium linear alkylbenzene sulfonate but factors like ambient temperature, contamination by organic materials, time of exposure and disinfectant concentration should be considered.