FAQ: California EHV-1 Outbreak

by US Equestrian Communications Department | Feb 25, 2022, 6:09 PM EST

Lexington, Ky - In conjunction with the California Department of Food and Agriculture (CDFA), USEF has created the following FAQ to provide our members with up to date information regarding the EHV-1 outbreak. The responses below are based on information available to USEF at the time of distribution. The situation in California is fluid. USEF will provide updates as additional information becomes available.

1. What is Equine Herpes Virus?
   Equine Herpes Virus-1 (EHV-1) is a virus that is present in the environment and found in most horses all over the world. Horses are typically exposed to the virus at a young age with no serious side effects.
   

2. Are there different strains of EHV-1?
   There are two strains of EHV-1:

   1. The wild-type (aka non-neuropathogenic) strain; and

   2. The mutant-type (aka neuropathogenic) strain of EHV-1.
      
      It is important to note that neurologic symptoms have been identified with both strains of the virus.
      

3. What is Equine Herpes Myeloencephalopathy (EHM)?
   EHM is the neurological disease syndrome caused by the EHV-1. In this syndrome, the EHV-1 virus damages blood vessels in the brain and spinal cord causing the various neurologic clinical signs.
   

4. How does the disease spread?
   EHV-1 is spread by direct horse-to-horse contact. The virus may also be spread indirectly through contact with objects contaminated with the virus, such as clothing, human hands, equipment, tack, trailers, feed, water buckets, and wash rags. The virus can become airborne but only for short distances.
   

5. How many horses have tested positive for EHV-1 that were on the grounds at DIHP or associated with horses that had been on the grounds of DIHP?
   To date, 18 horses have confirmed positive for EHV-1. Some of these horses tested positive after leaving DIHP.
   

6. How many horses have tested positive for EHM that were on the grounds at DIHP?
   To date, three (3) horses from DIHP have confirmed positive for EHM (EHV-1 infection with neurological signs). One of these horses had to be euthanized.
   

7. Is there a relationship between DIHP and the euthanized horse that competed at LAEC?
   At this time, there is no known direct link between the DIHP and the euthanized horse confirmed positive for EHM (EHV-1 infection with neurological signs) that competed at LAEC.
   

8. Did horses leave DIHP and within 7 days compete at LAEC against LAEC’s protocols?
   We have reports that 4 horses left DIHP and within 7 days competed at LAEC against their protocols. Those horses were removed when this became known to management. USEF is investigating these reports.
   

9. Is there a relationship between DIHP and the euthanized horse in San Juan Capistrano?
   The euthanized horse in San Juan Capistrano confirmed positive for EHM (EHV-1 infection with neurological signs) had not been to DIHP, but was exposed to other horses upon their return from DIHP. One of the returned horses confirmed positive for EHV-1.
   

10. Where can I find up-to-date information this?
    Updates on confirmed cases are reported on the California Department of Food and Agriculture and Equine Disease Communication Center websites. Please do not rely on information from social media or word of mouth.

Reminder: USEF Mandate on EHV-1 Restriction of Entries

February 24, 2022

Reminder: USEF Mandate on EHV-1 Restriction of Entries

In an effort to mitigate the risk of virus transmission, the USEF is requiring the following protocols, which are effective immediately and until further notice.
 

1.Isolate your horses
Horses that within the last 14 days were on the grounds at Desert International Horse Park (DIHP) or have been in-contact with these DIHP horses must be isolated.
2.Take rectal temperatures
Rectal temperatures of all of your horses should be taken and recorded twice daily. Horses that develop a fever should be examined by a veterinarian.
3.Laboratory testing for EHV-1
Horses that were on the grounds at DIHP must meet the following requirements:
EITHER
Two samples taken using nasopharyngeal swabs must be analyzed by PCR testing on day 7 and day 14. Day 0 is considered to be the day your horse is in a new location. Both swabs must result in negative test results to EHV-1 in order to satisfy the requirements of the USEF. If either of the tests generate a positive result, the horse must remain in isolation and be re-tested. It is necessary to have two negative test results, taken at least seven days apart to fulfill USEF requirements.
OR
The horse must be isolated for 21 days, rectal temperature must be taken and recorded during the isolation period. Samples to be taken after day 21 using a nasopharyngeal swab to test for EHV-1 via PCR analysis. Day 0 is considered to be the day your horse is in a new location. The swab must result in negative PCR test result to EHV-1. If the tests generate a positive result, the horse must remain in isolation for an additional seven days and be re-tested.
4.Release from Isolation
Horses must only be released from isolation on the advice of your veterinarian.
5.Return to Competition
Horses that have been on the grounds at DIHP within 14 days preceding a USEF competition are not permitted to enter any USEF competition ground until they have fulfilled the testing requirements described above. Test results must be submitted via email to EHV@usef.org to obtain clearance from this restriction.
6.Penalties
Noncompliance with these protocols will result in penalties imposed on trainers and owners as well as competitions that knowingly permit noncompliant horses on the grounds.

Horses outside the DIHP show venue:

Your horse may have come into contact with other horses apart from those at the DIHP show venue, e.g. at your home stables or during your journey home. We recommend that you consult your usual veterinarian to advise you on biosecurity measures you should implement.

Resources

•California Department of Food and Agriculture•Equine Disease Communication Center•Submitting equine test results only: EHV@usef.org•Questions regarding eligibility: EHVhelp@usef.org

Biosecurity requirements and best practices:

•Avoid animal-to-animal contact•Do not share equipment between horses. IF YOU MUST SHARE, scrub and clean equipment with detergent and dry completely between shared use.•When filling water buckets, DO NOT dip the end of the hose in each bucket. Hold the hose above the water when filling.•Wash/sanitize hands thoroughly before and after direct horse contact•Limit human-horse contact•Check and record temperatures twice daily•Any suspicion of illness in horses, including a temperature over 101.5°F, should be immediately reported to the show office and veterinarian.•Immediately isolate and/or quarantine any horse exhibiting symptoms of illness•DO NOT travel to another competition for 14 days•Because humans can be a means of disease transmission, avoid moving between barns unless absolutely necessary

USEF LEARNING CENTER VIDEO

Biosecurity Measures for Horses at Home and at Competitions

Comprehensive information on biosecurity protocols can be found here:

•Competition Safety and Biosecurity•Brochure: Biosecurity Measures for Horses at Home and at Competitions

July 25, 2021 Important EHV-1 Update

July 25, 2021

Equine Herpesvirus- Neurologic

Sonoma County, CA

Alert ID: 2139

Status: Confirmed Case(s) - Official Quarantine

Source: California Department of Food and Agriculture

Number Confirmed: 5;

Number Suspected: 4;

Number Exposed: 19

Facility Type: Showgrounds;

Horse #1: Age: 6; Gender: Mare; Breed: Warmblood (WB); Onset of Clinical Signs: 7/23/2021;

Clinical Signs: Hind-end Weakness, Limb edema, Nystagmus, Recumbency; Confirmation Date: 7/24/2021; Horse Status: Euthanized; Vaccination Status: Vaccinated;

Horse #2: Age: 15; Gender: Gelding; Breed: Warmblood (WB); Onset of Clinical Signs: 7/22/2021;

Clinical Signs: Ataxia, Cranial Nerve Deficit, Fever, Neurologic Signs, Urine Dribbling; Confirmation Date: 7/23/2021; Horse Status: Affected And Alive; Vaccination Status: Status Unknow

Notes: A 6-year-old Warmblood mare displaying neurological signs has been confirmed positive for EHM secondary to EHV-1. She attended a show in Sonoma County from 7/19-7/24 but did not compete, and event management has notified all participants to monitor temperatures twice daily and report any fevers or neurologic signs to their veterinarians and CDFA, as well as isolate all horses returning from shows at their home premises for at least 7 days. CDFA was onsite, and 19 exposed horses from the index mare’s barn were removed from the show facility and have been isolated and quarantined at the home premises in Sacramento County with the remaining 18 horses at the home premises with twice daily temperature monitoring and enhanced biosecurity measures. Six (6) horses from the home premises displaying fever and/or limb edema have also tested positive for EHV-1. A 15-year-old Warmblood gelding at the home premises that was febrile and tested positive for EHV-1 began displaying neurological signs, ataxia, urine dribbling, and cranial nerve deficits and was moved to isolation under quarantine at a veterinary hospital for care. CDFA continues to actively monitor the situation.

https://equinediseasecc.org/search/alert/2139

For more information

NEW: EHV-1 Quarantine in Santa Clara County

NEW: EHV-1 Quarantine in Santa Clara County

March 24, 2021: A 21-year-old Quarter Horse mare from Santa Clara County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 on March 23rd. The horse is alive and is being treated in isolation at a veterinary hospital. The home premises has been quarantined with enhanced biosecurity measures in place and twice daily temperature monitoring. The clinical horse has no recent travel history and no links to any other EHV-1 cases. The home premises hosted an event on March 21st, and one asymptomatic horse from the home premise competed in an event from March 19th – 21st.  Event managers have been notified, and are encouraging all owners of potentially exposed horses to perform twice daily temperature monitoring, limit movement, and practice enhanced biosecurity measures for the next 14 days. CDFA will be onsite and continue to actively monitor exposed horses.

Equine Herpesvirus- Neurologic (EHM) confirmed in Sonoma County

Equine Herpes Myeloencephalopathy (EHM) Updates:

 

NEW: EHV-1 Quarantine in Sonoma County

March 22, 2021: No additional cases to report. CDFA continues to monitor the situation closely.

March 16, 2021: A 21-year-old Warmblood mare from Sonoma County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 (neuropathogenic strain) on March 15th; the horse is alive and is being treated in isolation at a veterinary hospital. Horses on the home premises have been quarantined with enhanced biosecurity measures and twice daily temperature monitoring. There is no known risk of exposure out of this facility to any local events. The clinical horse has no recent travel history and no links to any other EHV-1 cases. CDFA will continue to actively monitor exposed horses. https://www.cdfa.ca.gov/ahfss/animal_health/equine_herpes_virus.html

View Equine Herpes Myeloencephalopathy Fact Sheet