Sacramento County officials detect West Nile virus in mosquitoes for first time in 2025
A sample of mosquitoes in Sacramento County has tested positive for West Nile virus for the first time in 2025.
The Sacramento-Yolo Mosquito and Vector Control District announced the positive test — from a sample collected near Gibson Ranch in Elverta — and said Wednesday that residents should take precautions, such as using bug repellent, to avoid contracting the virus.
As of Friday, the virus had been detected in 74 mosquito samples statewide, an increase from 52 at the same point last summer, according to the California Department of Public Health. Last year, California had 131 confirmed human cases of West Nile and 12 deaths due to the virus.
This season, no humans in California have yet tested positive for the disease, CDPH officials said in last week’s update. Samples of the virus this year have been mainly in the south state, though the virus has been detected in 12 dead birds across Alameda and Santa Clara counties.
“As we expected, the very warm weather we’ve had recently increased the number of mosquitoes and accelerated virus activity,” Gary Goodman, the vector control district manager, said in a statement. “It’s important for residents to take these findings seriously and do everything they can to protect themselves.”
There is no vaccine for humans to stave off a West Nile virus infection, according to the U.S. Centers for Disease Control and Prevention, but most people who are infected do not experience symptoms.
Now that the first mosquito case in the capital region has been identified, the Sacramento-Yolo Mosquito and Vector Control District will expand its monitoring of mosquitoes and may spray to eradicate hot spots, the statement said.
The vector control district recommends using an insect repellent when doing outdoor activities to help prevent West Nile spread. They also recommend limiting time outside during dawn and dusk and draining stagnant water to eliminate breeding sites.
CDPH encourages residents to report dead birds by calling the department’s hot line at 877-968-2473 (877-WNV-BIRD). The state has counted 14 dead birds with West Nile virus so far this year.
Residents can call the district at 800-429-1022 or visit fightthebite.net.