MODESTO — West Nile virus has been detected in Stanislaus County for the first time this year, prompting renewed warnings from local mosquito abatement officials as summer temperatures fuel mosquito activity across the Central Valley.

The Turlock Mosquito Abatement District — which serves communities including Newman — confirmed that mosquito samples collected June 16 tested positive for the virus. The finding marks the first detection of the season in Stanislaus County. Merced County, whose district covers Gustine, had not yet reported a positive mosquito sample as of Friday, according to the California West Nile virus website.

A positive mosquito sample, often called a “mosquito pool,” indicates that a group of mosquitoes collected for testing carried the virus. No human cases have been reported locally, but officials say the detection means residents should take steps now to protect themselves from mosquito bites.

Statewide, West Nile activity is rising. As of June 26, California had logged one human case, 89 dead birds, 67 positive mosquito samples and one infected horse. The virus has been detected in 18 counties.

West Nile virus, first identified in California in 2003, spreads to humans through the bite of an infected mosquito. Mosquitoes become infected after feeding on birds carrying the virus. Most people experience no symptoms, but about one in five develop fever, headaches, joint pain, rash or fatigue, according to the Centers for Disease Control and Prevention. Fewer than 1 percent develop severe neurological complications such as meningitis or encephalitis, which can be fatal, particularly for adults over 50 or those with underlying health conditions.

There is no vaccine or antiviral treatment for West Nile virus. Mild symptoms may last weeks, while severe cases can cause long‑term or permanent effects.

Local mosquito districts are urging residents to eliminate standing water, which provides ideal breeding sites. Unmaintained swimming pools remain a major concern in urban areas.

Recommended prevention steps include:

• Dumping or draining standing water from containers, birdbaths, buckets and pet bowls.
• Maintaining or treating swimming pools.
• Avoiding stagnant agricultural water for more than three days.
• Using EPA‑registered repellents containing DEET, Picaridin or Oil of Lemon Eucalyptus.
• Limiting outdoor activity at dawn and dusk.
• Keeping window and door screens in good repair.
• Reporting neglected pools or mosquito hotspots.

Dead birds — an early indicator of West Nile activity — can be reported to the state hotline at 1‑877‑WNV‑BIRD or online at westnile.ca.gov/report.

Residents in the Turlock Mosquito Abatement District can report mosquito issues or neglected pools at (209) 634‑1234. Merced County residents can report concerns at (209) 722‑1527. Both districts provide services at no cost.

Officials expect mosquito activity and virus detections to increase through the summer.