The Manitoba Horse Council has confirmed cases of Equine herpesvirus (EHV-1) which has caused abortions and neurologic disease starting 3 weeks ago in southwest Manitoba, according to a Equine Disease Communication Center (EDCC) alert.
Veterinarians initiated a strict quarantine of 105 horses on the property. Eight fatalities have resulted from neurologic disease with an additional 2 horses currently showing with neurologic signs. The premises is isolated with no movement of horses on or off the property since outbreak started. Strict biosecurity measures are in place.
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.