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.

Fresno, San Luis Obispo, Santa Barbara, Ventura Counties, CA
Outbreak Identifier: 5645
Alert ID: 3174
August 15, 2023
Confirmed Case(s) - Official Quarantine


VSV Situation Report 8/15/2023

Since the last situation report (8/8/2023), there have been 12 new VSV-affected equine premises identified (3 confirmed positive, 9 suspect) in California, including a new affected county, Fresno County, California.  All confirmed cases have been vesicular stomatitis New Jersey virus (VSNJV) serotype. Updates are as follows:  


  • Fresno County (New Infected County) – 1 confirmed positive equine premises
  • San Luis Obispo County – 1 new confirmed positive and 2 new suspect equine premises
  • Santa Barbara County – 1 new confirmed positive and 2 new suspect equine premises
  • Ventura County – 5 new suspect equine premises 
  • Since the last situation report (8/8/2023), the following previously confirmed positive or suspect premises have been released from quarantine: 1 premises in Los Angeles County, 3 premises in Riverside County, 11 premises in San Diego County, 3 premises in San Luis Obispo County, 1 premises in Santa Barbara County, and 16 premises in Ventura County. 


  • No new confirmed positive premises have been identified.
  • Since the last situation report (8/8/2023), 1 previously confirmed positive premises was released from quarantine in White Pine County.    


  • No new confirmed positive premises have been identified. 

Since the start of the outbreak (5/17/2023), 189 VSV-affected premises have been identified (65 confirmed positive, 124 suspect) in 3 states, California, Nevada, and Texas.  One hundred eighty-six (186) of these premises have had only equine species clinically affected, two (2) premises have had clinically affected cattle (San Diego County, California), and one (1) premises has had clinically affected rhinoceros (San Diego County, California). 

California has identified 186 affected premises (62 confirmed positive, 124 suspect) in 9 counties (Fresno, Los Angeles, Orange, Riverside, San Bernardino, San Diego, San Luis Obispo, Santa Barbara, and Ventura Counties).  Texas identified 2 affected premises (2 confirmed positive) in 2 counties (Maverick and Shackelford Counties).  Nevada identified 1 affected premises (1 confirmed positive) in 1 county (White Pine County, Nevada).  

Of the 189 total VSV-affected premises, 141 premises have completed the quarantine period with no new clinical cases and have been released from quarantine.  Forty-eight (48) premises remain quarantined.  

Additional information and maps of the affected area are contained in the situation report which is posted publicly on the APHIS website and accessible at the following link:  https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/equine/vsv/vesicular-stomatitis

Previous Alerts: 3152, 3145, 3126, 3115, 3111, 3099, 3090, 3085, 3071, 3066, 3060