Environmental persistence of equid herpesvirus type-1

Background Equid herpesvirus type 1 (EHV-1) is ubiquitous in equine populations causing respiratory disease, and complications including late-term abortion and neurological disease. Eradication of EHV-1 from housing environments that typically contain unsealed wood and porous bedding materials can be challenging. However, consideration should be given to take advantage of the viral envelope's susceptibility to environmental conditions. Objective To determine environmental persistence of EHV-1 on materials and in environmental conditions commonly found in equine facilities. We hypothesised that environmental conditions and materials would limit environmental persistence of EHV-1 in horse housing environments. Study design Experimental study. Methods Standard inoculum of EHV-1 strain OH03 was applied to leather, polyester-cotton fabric, two bedding materials (pinewood shavings and wheat straw) and polystyrene (plastic), and placed under three different environmental conditions (4 degrees C, indoors and outdoors). Virus titration and quantitative PCR (qPCR) were performed at six time points between 0 and 48 hours and the number of plaque-forming units (PFUs) was determined. Results Viable EHV-1 was recovered up to 48 hours from all material-environmental condition combinations, with persistence decreasing over time. In general, outdoor environment had the greatest impact, irrespective of material tested, followed by indoor environment and 4 degrees C. On average, wood shavings had the greatest impact on persistence, followed by leather, straw, fabric and polystyrene. Main limitations The inoculum used in this study was not in a milieu consistent with nasal secretions. As such, virus particles may have been more sensitive to the materials and/or environmental conditions evaluated. Conclusions Environmental factors had variable effects on environmental persistence. Although there were significant reductions in PFUs within the first 3 hours, irrespective of environment-material evaluated, viable virus was still recovered at 48 hours likely representing a transmission risk. Barrier precautions should be used to prevent spread of EHV-1 from unrecognised environmental reservoirs.

Automated summary

This study investigated the environmental persistence of EHV-1 on different materials and environmental conditions commonly found in equine facilities. The results showed that wood shavings had the greatest impact on the virus persistence. Despite significant reductions in virus titers within 3 hours, viable virus was still recovered at 48 hours, indicating a potential transmission risk.