By NewsDesk  @infectiousdiseasenews

Since mid-November 2019, an outbreak of Equine Herpesvirus 1 (EHV-1) has been reported at the Remington Park Racetrack, in Oklahoma County.


Through Jan. 10, 2020, the Oklahoma Department of Agriculture has reported 17 confirmed cases with approximately 120 horses exposed.

As of Friday, an additional 2 horses were released from quarantine. These horses completed 14 days with no exposure to an EHV-1 positive horse, no fevers, no symptoms compatible with EHV-1, and two negative tests 7 days apart. These horses were from the second quarantine barn but were moved to separate barns after the race meet ended. 17 horses remain in quarantine at Remington Park, 3 of these are in the Isolation Barn. Enhanced biosecurity measures and twice daily temperature monitoring is in place. ODAFF personnel are on-site and continue to monitor the situation.

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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.