Outbreaks | Equine Disease Communication Center

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.

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West Nile Virus

Merced County, CA

Outbreak Identifier: 7539

Alert ID: 5110

August 06, 2026

Confirmed Case(s) - No Quarantine

Source: California Department of Food and Agriculture

Number Confirmed: 1;

Horse 1:
Age: 6; Gender: Gelding; Breed: Warmblood (WB); Onset of Clinical Signs: 7/30/2026; Clinical Signs: ataxia (all 4 limbs), hypersensitivity, muscle fasciculations, wall leaning; Horse Status: Affected And Alive; Vaccination Status: Vaccinated;

Comments: The fourth (4th) equine case of West Nile Virus in California in 2026 was confirmed in Merced County. On August 6, 2026, a vaccinated 6-year-old Warmblood gelding in Merced County displaying neurologic signs was confirmed positive for West Nile Virus. The gelding is alive and recovering.;

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