San Joaquin County residents are being urged to take mosquito prevention seriously after the first West Nile virus-positive mosquitoes of 2026 were detected in the county.
The San Joaquin County Mosquito and Vector Control District announced that its vector-borne disease surveillance program found the season’s first mosquitoes positive for West Nile virus in a sample collected from Upper Jones Tract in the San Joaquin Delta islands, ZIP code 95219.
The detection marks the beginning of West Nile virus activity this year in San Joaquin County. District officials say West Nile virus has been detected in the county every summer for more than 20 years, and mosquito activity typically increases as temperatures rise.
West Nile virus is maintained in nature through a cycle between wild birds and mosquitoes. While most people infected with the virus do not develop symptoms, some may experience mild to severe illness.
“As temperatures continue to rise this summer, residents should take steps to reduce mosquito development around their homes and protect themselves from mosquito bites,” said Sumiko De La Vega, Public Information Officer with the District. “We encourage residents to inspect their yards each week for standing water where mosquitoes can develop and to use EPA-registered mosquito repellents when outdoors.”
The District will continue mosquito surveillance and disease testing throughout the season. The data collected helps guide science-based mosquito control efforts in areas where mosquito activity or disease risk may be elevated.
Residents can help protect themselves, their families and their neighborhoods by taking simple precautions:
Eliminate standing water around your property, including small amounts that can collect in flowerpots, buckets, bird baths, pet dishes, clogged gutters, old tires and other containers. Even as little as a tablespoon of water can support mosquito development.
Use an EPA-registered insect repellent when outdoors and follow label directions. Effective ingredients include DEET, picaridin, IR3535, or oil of lemon eucalyptus.
Avoid spending time outside when mosquitoes are most active, especially at dawn and dusk and during the first two hours after sunset.
Wear loose-fitting long sleeves and long pants when outdoors, when practical.
Keep mosquitoes out of your home by making sure window and door screens fit tightly and are in good repair.
Residents with horses are encouraged to contact their veterinarian for information about vaccination against West Nile virus.
For mosquito problems, residents may request an inspection online through the District’s website at www.sjmosquito.org. Dead birds can be reported by calling 1-877-WNV-BIRD, or 1-877-968-2473, or by visiting www.westnile.ca.gov.
To learn more about the San Joaquin County Mosquito and Vector Control District and its mosquito control activities, visit www.sjmosquito.org or call (209) 982-4675. The District office is available Monday through Friday from 7:00 a.m. to 3:30 p.m. Whenever possible, residents are encouraged to use the website to help reduce call volume to office staff.