A study reveals more about how long the EHV-1 virus can survive on a range of materials and under different environmental conditions. H&H speaks to researchers and vets to find out more, and what this means for riders
VIABLE equine herpes virus (EHV-1) lingered on a range of environmental materials for 48 hours, a study has found.
Researchers from the Center for Companion Animal Studies, Colorado State University, found that the virus’s persistence, on a range of materials commonly found in yards, was likely to represent a transmission risk.
For the study, published in the Equine Veterinary Journal, the virus was applied to leather, polyester/cotton fabric, bedding materials – pinewood shavings and wheat straw – and plastic, and left in three different environmental conditions; 4°C, indoors and outdoors.
They found that although there were “significant reductions” in concentration in the first three hours, viable virus was still recovered after 48 hours.
“Barrier precautions should be used to prevent spread of EHV‐1 from unrecognised environmental reservoirs,” the study concluded.
Researcher Brandy A Burgess, an associate professor of epidemiology and infection control, and director of infection control at the University of Georgia’s veterinary teaching hospital, told H&H EHV-1 can be a challenge to manage, especially in the US where states have different laws.
“So it’s really something we want to understand more about, and about how to manage it,” she said.
She added that many horses can shed the virus without showing symptoms, so measures to mitigate spread should help decrease the risk of outbreaks.
“Another thing to note is that this was the virus all by itself,” she said. “In nature, it would be shed in saliva or mucus, which protects the bug, and so we’d expect it to last longer.”
Dr Burgess said materials that are fibrous or porous – those that cannot be scrubbed clean and disinfected – can harbour the virus, so the message for owners is “don’t share”.
“We shouldn’t be sharing any tack, brushes, rugs or buckets, not just because of this but because of anything that can be spread,” she said. “You shouldn’t walk through a facility and pet other horses; you’re at a competition, not a zoo; keep your hands to yourself.”
Sealing wooden surfaces, with marine paint or similar, will make them easier to clean and disinfect, and bedding should be changed between horses.
“What we’re trying to do is simple; to disrupt the chain of transmission,” she said.
David Rendle, chair of the British Equine Veterinary Association health and medicines committee, told H&H the study provides useful information on EHV’s ability to survive.
“But it is always difficult to extrapolate the results of studies of this type to a field setting,” he said. “The situation with EHV is further complicated by large numbers of horses carrying the virus without showing any signs of infection and acting as a reservoir for disease. Horses with signs of infection with herpes virus (coughing, nasal discharge, high temperature, abortion, wobbly hindlegs, difficulty urinating) remain the most likely source of infection for other horses. But this study highlights the importance of disinfection and biosecurity in general in preventing the spread of EHV.”
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