Environmental persistence of equid herpesvirus type‐1

Abstract

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°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°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.

Environmental Detection and Potential Transmission of Equine Herpesviruses

“…The results from this study indicate that EHV stability on fomites is largely dependent on the surface it comes into contact with and that it can remain infectious up to 42 days after exposure. A recent study showed that EHV-1 can remain viable in the environment on materials such as leather, fabric, wood shavings, wheat straw, and polystyrene for at least 48 h [ 13 ]. It is unclear if animals can contract EHV infections from contaminated surfaces, which likely depends on the breed or species, dose of virus shed, exposure of virus to environmental factors such UV radiation and desiccation, and frequency of animal interaction with such surfaces.…”

“…At present, very few studies on the effect of physicochemical factors on viability of EHVs in the environment are available [ 13 , 22 , 41 ]. Therefore, in order to prevent EHV spreading in captive or domestic equids, disinfection of surfaces may be recommendable under certain circumstances.…”

Investigation of the Use of Non-Invasive Samples for the Molecular Detection of EHV-1 in Horses with and without Clinical Infection

“…Further, the detection of EHV-1 by qPCR did not allow drawing any conclusions regarding the contagiousness of these horses. A recent study determined that irrespective of the environment–material evaluated (leather, polyester-cotton fabric, pinewood shavings, wheat straw, and plastic), viable virus could still be recovered at 48 h following standard inoculation with EHV-1 [ 25 ]. An additional study showed that EHV-1 remained stable and infectious in water for up to three weeks [ 26 ].…”

New Insights into the Management of an EHV-1 (Equine Hospital) Outbreak

“…EHV-1 is purportedly environmentally labile and does not survive well outside its equine host; it should, therefore, be easily killed by treatment with detergents, lipid solvents, heat and common disinfectants. Saklou at al., however, showed that EHV-1 can survive 48 h on environmental material [ 15 ]. Experimentally, the virus has survived for up to a week at ambient temperatures when dried into paper, wood and rope and up to 35 days on horsehair and burlap [ 16 ].…”