Equine Herpesvirus type 1 (EHV‐1) in the Environment: How Long Will It Stay Infective?

Introduction Equine herpesvirus type 1 (EHV-1) is a highly contagious agent for horses, able to cause outbreaks of respiratory disease, myelopathy and/or abortion. Horizontal transmission is directly through nasopharyngeal droplet transmission or, indirectly, through fomite transmission. Once in the environment viral maintenance of infectivity will depend on a variety of factors associated with viral envelope integrity. Adsorptive and surface tension forces, temperature fluctuations and UV-light exposure have been shown to affect envelope integrity in other herpesviridae. Aims We hypothesised that viral survival will be different if placed on various surfaces or materials, and if placed in different environmental conditions. Methods An EHV-1 suspension was placed on surfaces or materials: plastic, fabric, leather and stall bedding materials: shavings and straw. Materials were placed in different environments: constant 4°C, ‘barn’ and ‘outdoor environment’. Samples of each material and environment were collected at time points 0, 3, 12, 24, 36 and 48 h followed by viral titration and quantitative PCR analysis. Statistical analysis used generalised linear models with random-effects mixed models controlling for repeated measures. Statistical significance was assumed when P<0.05. Results Results showed significant differences upon contact (t = 0) of the viral suspension with materials, most noticeable with shavings and leather. Most materials and in environmental conditions other than 4°C showed a rapid decrease in viral survival, especially during the first 3 h. While results show significant reduction on some surfaces and materials over others, it is important to realise that viral maintenance of infectivity was still significant under simulated ‘barn conditions’ following the 3 h time point. Conclusions and practical significance These results emphasise the importance of the prudent use of biosecurity protocols when mitigating an EHV-1 outbreak. Ethical animal research Not applicable. Sources of funding: 1) Student was funded from an internal grant (DVM student grant) at CSU. 2) CSU Equine Neurology Research Fund. Competing interests: None.