San Bernardino County health officials confirmed the first human case of West Nile virus of 2026, involving a resident living in the city of San Bernardino, according to a written statement released by the San Bernardino County Public Health Department.
County Health Officials Confirm First 2026 Case
The San Bernardino County Public Health Department announced the diagnosis in a statement issued on Sept. 16, 2026. This development marks the first reported human infection in the county since 2024, when health officials logged a total of seven cases. Following the confirmation, local health authorities urged residents to step up precautions against mosquito bites, noting that warmer months drive up vector activity across the region. “West Nile virus infection continues to be a health concern in our region, particularly during the warmer months when mosquito activity increases,” said San Bernardino County Health Officer Sharon Wang, D.O., in the public statement. Wang advised that residents can reduce personal risk by applying insect repellent, wearing protective garments, and clearing standing water around residential properties.
Transmission, Symptoms, and Severe Health Risks
According to San Bernardino County Public Health, the virus spreads through the bite of an infected Culex species mosquito that previously fed on an infected bird. Infected individuals typically develop symptoms three to five days after a mosquito bite, though many carriers experience no symptoms at all. When symptoms do appear, they commonly include fever, headache, body aches, nausea, vomiting, and a skin rash. Public Health data indicates that fewer than 1% of infected individuals develop severe neuroinvasive illness, which can trigger inflammation of the brain or surrounding tissues. Older adults and individuals with compromised immune systems or underlying conditions—such as cancer, diabetes, hypertension, and kidney disease—face a substantially higher risk of severe illness. Additionally, people who have undergone organ transplants or take immunosuppressive medications are classified at increased risk. Officials recommend seeking immediate medical care if symptoms escalate to high fever, severe headache, neck stiffness, sudden vision loss, numbness or tingling, confusion, muscle weakness, paralysis, or loss of consciousness.
Prevention and Mosquito Control Measures
To curb mosquito breeding and lower infection risks, San Bernardino County Public Health recommends eliminating standing water around homes, including water pooling in birdbaths, old tires, buckets, flowerpots, and clogged gutters. Property owners must ensure swimming pools remain clean, circulating, and properly chlorinated. Outdoors, residents are encouraged to wear socks, shoes, light-colored, loose-fitting long pants, and long-sleeved shirts. Health officials recommend using insect repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus while strictly following product label instructions. Homes should also feature tight-fitting window and door screens free of tears or holes. Residents can report increased mosquito activity or breeding sites to San Bernardino County Public Health Environmental Health Services by calling 800-442-2283 or visiting the San Bernardino County Mosquito and Vector Control website. Dead or sick birds can be reported by calling 1-877-WNV-BIRD (1-877-968-2473) or via California’s West Nile virus reporting website.
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