Northern California’s first human West Nile virus case of the year has been confirmed in Butte County, according to local health officials.

Local health officials say Chicago has reached a “high risk” level of the West Nile virus because mosquitoes are testing positive earlier and could lead to a longer lasting, heightened risk this

A crow from Walnut Creek has tested positive for West Nile virus (WNV) in Contra Costa County, confirmed the Contra Costa Mosquito and Vector Control District on Friday. This is the second West Nile-virus infected bird this year after a California scrub jay from San Ramon tested positive on July 21.