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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.



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West Nile Virus
Union County, OR
Outbreak Identifier: 7565
Alert ID: 5137
August 14, 2026
Confirmed Case(s) - No Quarantine

State Department of Agriculture

Number Confirmed: 1; 
Number Exposed: Unknown; 
Comments: Unvaccinated horse (laboratory confirmed 8/11/2026);
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West Nile Virus
Benton County, WA
Outbreak Identifier: 7564
Alert ID: 5136
August 14, 2026
Confirmed Case(s) - No Quarantine

Asst State Veterinarian-WSDA

Number Confirmed: 1; 
Number Exposed: Unknown; 
Facility Type: Private Facility; 
Comments: Horse was 2 yrs old and unvaccinated;
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West Nile Virus
Todd County, MN
Outbreak Identifier: 7563
Alert ID: 5135
August 14, 2026
Confirmed Case(s) - No Quarantine

State Animal Health Official

Number Confirmed: 1; 
Number Exposed: 15; 
Facility Type: Farm; 

Horse 1: 
Age: 6; Gender: Gelding; Breed: Standardbred; Usage: Carriage; Onset of Clinical Signs: 8/3/2026; Clinical Signs: Lethargy, ataxia worse in hind limbs than forelimbs.; Horse Status: Affected And Alive; Vaccination Status: Unvaccinated;
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West Nile Virus
Utah County, UT
Outbreak Identifier: 7561
Alert ID: 5133
August 13, 2026
Confirmed Case(s) - No Quarantine

Utah Department of Agriculture and Food

Number Confirmed: 1; 
Number Exposed: 1; 
Number Euthanized: 1; 
Facility Type: Private Facility; 

Horse 1: 
Age: 16; Gender: Mare; Breed: Quarter Horse (QH); Usage: Ranch Horse; Onset of Clinical Signs: 8/8/2026; Clinical Signs: 8/8/26: ataxia and no muscle fasciculations 8/12/26: down and euthanized; Confirmation Date: 8/12/2026; Horse Status: Euthanized; Vaccination Status: Unvaccinated;
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West Nile Virus
Morgan County, UT
Outbreak Identifier: 7560
Alert ID: 5132
August 13, 2026
Confirmed Case(s) - No Quarantine

Utah Department of Agriculture and Food

Number Confirmed: 1; 
Number Exposed: 9; 
Facility Type: Private Facility; 

Horse 1: 
Age: Yearling; Gender: Filly; Breed: Quarter Horse (QH); Usage: Breeding; Onset of Clinical Signs: 8/9/2026; Clinical Signs: 8/9/26: severe colic signs (down and rolling) 8/10/26: 3/4 ataxia on all 4 limbs 8/12/26: recovering; Confirmation Date: 8/13/2026; Horse Status: Recovering; Vaccination Status: Undervaccinated;

Comments: Vaccinated and boostered 1 m later, but not this spring.;
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West Nile Virus
Benton County, WA
Outbreak Identifier: 7547
Alert ID: 5119
August 11, 2026
Confirmed Case(s) - No Quarantine

WSDA and attending veterinarian

Number Confirmed: 1; 
Facility Type: Private Facility; 
Comments: 2 year old non-vaccinated gelding. Severely ataxic at time of blood draw. Horse died prior to receiving lab confirmation of WNV infection.;
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West Nile Virus
Placer County, CA
Outbreak Identifier: 7545
Alert ID: 5117
August 10, 2026
Confirmed Case(s) - No Quarantine

California Department of Food and Agriculture

Number Confirmed: 1; 

Horse 1: 
Age: 3; Gender: Gelding; Breed: Quarter Horse (QH); Onset of Clinical Signs: 8/4/2026; Clinical Signs: ataxia (all 4 limbs), hypersensitivity, mild muscle fasciculations, acting sedated; Confirmation Date: 8/7/2026; Horse Status: Affected And Alive; Vaccination Status: Unvaccinated;

Comments: The fifth (5th) equine case of West Nile Virus in California in 2026 was confirmed in Placer County. On August 7, 2026, an unvaccinated 3-year-old Quarter Horse gelding in Placer County displaying neurologic signs was confirmed positive for West Nile Virus. The gelding is alive and recovering.;
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West Nile Virus
Polk County, MN
Outbreak Identifier: 7544
Alert ID: 5116
August 10, 2026
Confirmed Case(s) - No Quarantine

State Animal Health Official

Number Confirmed: 1; 
Number Exposed: Unknown; 
Facility Type: Farm; 

Horse 1: 
Age: 3; Gender: Gelding; Breed: Standardbred; Usage: Carriage; Onset of Clinical Signs: 8/1/2026; Clinical Signs: Weakness, ataxia; Confirmation Date: 8/14/2026; Horse Status: Recovering; Vaccination Status: Unvaccinated;
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West Nile Virus
Merced County, CA
Outbreak Identifier: 7539
Alert ID: 5110
August 06, 2026
Confirmed Case(s) - No Quarantine

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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West Nile Virus
Box Elder County, UT
Outbreak Identifier: 7538
Alert ID: 5109
August 06, 2026
Confirmed Case(s) - No Quarantine

Utah Department of Agriculture and Food

Number Confirmed: 1; 
Number Exposed: 2; 
Facility Type: Private Facility;
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