WNV transmission occurs when infected mosquitoes feed on animals, as well as humans, after having fed on infected birds. | Photo: iStock

Not long after West Nile virus (WNV) diagnoses in the California counties of San Bernardino, Fresno, Kern, Madera, and Stanislaus, the California Department of Food and Agriculture (CDFA) has confirmed two additional horses with the life-threatening disease.

The newest confirmed horses include a 12-year-old Quarter Horse mare of unknown vaccination status whose clinical signs began Aug. 17. The Kern County mare experienced ataxia (incoordination), crossing of her front legs, fever, and lethargy. She is reportedly recovering.

The other newly confirmed horse, a 3-year-old unvaccinated Quarter Horse gelding from Stanislaus County, showed clinical signs on Aug. 22 including ataxia, fever, lethargy, and poor appetite. He was confirmed positive on Aug. 30 and is reported to be affected and alive