On Dec 26, 2016 the State Veterinarian’s Office confirmed a positive PCR tests of nasal swabs and blood for the EHV-1 neurotropic strain in a 2-year old Thoroughbred gelding at the New Orleans Fairgrounds Race Track, according to a recent Equine Disease Communication Center (EDCC) alert.
The horse had been at the Fairgrounds since Dec 4, 2016 and broke with a fever on Dec 20th with no neurological signs. The horse responded to symptomatic treatment until Dec 25th when it developed neurological signs, was subsequently euthanized on the 26th and taken to the LSU school of veterinary medicine for necropsy.
The horse was confined to its stall in Barn #14 since Dec 20th and had no direct contact with any other horses, but Barn 14, which houses 46 other horses, is currently under quarantine by the LA State Veterinarian’s Office. Horses will be monitored and have temperatures twice daily with increased biosecurity on the premises. An investigation with the State Racing Commission is currently under way.
Equine Herpes Virus (EHV-1) infection in horses can cause respiratory disease, abortion in mares, neonatal foal death and neurological disease. The neurological form of the disease is known as Equine Herpes Myeloencephalopathy (EHM) and may be caused by damage to blood vessels of the brain and spinal cord associated with EHV-1 infection. EHM is most often due to the neuropathogenic strain of EHV-1, but may occasionally be caused by the non-neuropathogenic strain of the virus.
EHV-1 is easily spread and typically has an incubation period between 2-10 days. Respiratory shedding of the virus generally occurs for 7-10 days, but may persist longer in infected horses. For this reason, a twenty-one day isolation period of confirmed positive EHM cases is recommended along with stringent biosecurity protocols. Similar to herpes viruses in other species, the latent form of EHV-1 can reactivate at a later date, but generally with a low viral load posing a low risk of infecting other horses. Humans are not at risk of contracting the virus, however humans can act as an indirect mode of transmission.