Eighteen dead birds have tested positive for West Nile virus in Sacramento County this year.
Statewide, 49 dead birds have tested positive so far. The average for this point in the season is 22.
West Nile virus circulates among wild birds and is spread to humans by mosquito bites. People who get the virus, they can't transmit it to others.
Sacramento County Health Officer Doctor Phuong Luu says most infections are mild, but the risks grow for older adults and those with chronic conditions.
"Flu-like symptoms, maybe a little fever, maybe some headaches," adds Luu, " some fatigue, some muscle pain. But there is about a on percent chance of those who are infected progress to severe illness."
Joel Buettner of the Placer Mosquito and Vector Control District says reducing standing water is critical.
"Everything from the size of a bottle cap to not overwatering your lawn and filling up your yard drains and everything in between," says Buettner. "Try to limit that water to stand not more than 72 hours."
Mosquitoes that carry West Nile are most active at dawn and dusk.
"If you're feeling the mosquitoes buzzing around," adds Buettner, "that's the time you should be wearing repellent, or protective clothing, or just going inside until they subside."
California reported 117 confirmed human cases of West Nile virus last year. Eleven of those were fatal.