San Joaquin County Public Health Services has confirmed the first human case of West Nile virus (WNV) in the county this year. The case involves an older adult male and marks San Joaquin as the 14th county in California to report a human infection in 2025 — the 61st statewide to date.
“Mosquito bite prevention is always the best course of action,” said Dr. Maggie Park, San Joaquin County Public Health Officer. “We encourage residents to protect themselves by wearing EPA-approved repellents and following CDPH vector protection guidelines.”
Understanding the Risk
West Nile virus, first detected in California in 2003, has become the leading cause of mosquito-borne disease in the continental United States. Most people infected (around 80%) will show no symptoms, but about 1% may develop severe illness, including fever, severe headaches, neck stiffness, confusion, or disorientation. Those most at risk include people over 60 years old, or with weakened immune systems, diabetes, or kidney disease.
How to Stay Safe
Public Health officials recommend following these three key prevention steps:
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DRAIN standing water — Mosquitoes breed in stagnant water. Empty items such as flowerpots, buckets, tires, and pet bowls. Keep swimming pools clean and consider adding mosquitofish to ornamental ponds.
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AVOID outdoor activity during dawn and dusk, when mosquitoes are most active.
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PROTECT yourself by wearing long sleeves and pants and applying EPA-approved repellents containing DEET, Picaridin, IR3535, Oil of Lemon Eucalyptus, or PMD.
Report and Respond
Residents are urged to report dead birds — especially crows, jays, magpies, sparrows, finches, or hawks — as they can help track local WNV activity. Reports can be filed online at westnile.ca.gov or by calling 1-877-WNV-BIRD (1-877-968-2473).
The San Joaquin County Mosquito & Vector Control District also accepts reports of heavy mosquito infestations, daytime biting, or neglected swimming pools through sjmosquito.org. The agency offers free mosquitofish, which feed on mosquito larvae and naturally help control breeding.
Additional Resources