Nevada County has recently reported their first human case of West Nile virus (WNV) for 2025. As of September 5, 2025, the California Department of Public Health (CDPH) had received reports of 31 human cases this season, with most cases being reported from the southern Central Valley. WNV is a disease that is transmitted by the bites from infected mosquitoes. WNV first appeared in California in 2003, and infections occur most often in the summer and early fall when mosquitoes are active. WNV activity is at its annual peak in California, and the state expects to see a continued rise in human cases through the early fall. As we move into fall, residents should continue to take precautions against mosquito bites.

For most people, the risk of serious WNV illness is low; however, some people

See Full Page