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Disease Alerts

Updates on current disease outbreaks are listed here as they occur and will include the date listed, disease name, location and current status. Specific premises will not be named but the general location by town, county and state will be listed. When locations, events or horses are at risk they will be listed. Updates will be posted as they are received.


Equine Herpesvirus- Neurologic
San Mateo County, CA
Outbreak Identifier: 5230
Alert ID: 2608
June 06, 2022
Outbreak Update

California Department of Food and Agriculture

Number Confirmed: 2;
Number Exposed: 300;
Age: 15; Gender: Mare; Breed: Irish Sport Horse; Onset of Clinical Signs: 6/3/2022;
Clinical Signs: ataxia, dribbling urine, lack of anal tone; Confirmation Date: 6/6/2022; Horse Status: Euthanized; Vaccination Status: Vaccinated;
Notes: One (1) additional horse on the quarantined premises, a 15-year-old Irish Sport Horse mare, displaying neurological signs was confirmed positive for Equine Herpesvirus Myeloencephalopathy (EHM) secondary to equine herpesvirus-1 (EHV-1 non-neuropathogenic strain) on June 6th. The mare was euthanized on June 3rd due to severity of clinical signs. CDFA is actively monitoring the situation.;
Previous Alerts: 2606