San Bernardino County Public Health Department has confirmed the first human case of West Nile virus (WNV) in the county for 2026. The case was identified in a resident of the city of San Bernardino. This is the first reported human case in San Bernardino County since 2024, when seven cases were reported.
The San Bernardino County Public Health Department would like to emphasize the importance of taking steps to protect yourself and your family from mosquito bites when out in the community.
“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. “Residents can reduce their risk by using insect repellent, wearing protective clothing and eliminating standing water around their homes. These simple steps can help protect you, your family and your community.”
What you need to know
WNV spreads through the bite of an infected Culex species mosquito that has previously bitten or fed on an infected bird. Symptoms typically occur three to five days after a bite, although many people do not experience symptoms. Symptoms of WNV include fever, headache, body aches, nausea, vomiting and skin rash.
Fewer than 1 percent of people infected with WNV develop severe neuroinvasive illness, which can cause inflammation of the brain or surrounding tissues. The risk of severe illness is higher among older adults and people with weakened immune systems or certain medical conditions, including cancer, diabetes, hypertension and kidney disease, as well as people who have received an organ transplant or take medications that suppress the immune system.
Seek medical attention immediately if you experience any of the following symptoms:
- High fever
- Severe headache
- Neck stiffness
- Sudden vision loss
- Numbness or tingling
- Confusion
- Muscle weakness
- Paralysis
- Loss of consciousness
Preventing mosquito bites
Residents can continue enjoying outdoor activities while taking a few additional precautions to protect themselves and their families from mosquito bites:
- Drain: Take a few minutes to walk around your property to remove standing water where mosquitoes can lay eggs. Check birdbaths, ponds, old tires, buckets, flowerpots, clogged gutters and other areas where water collects. Maintain your pool by keeping the water clean, circulating, and properly chlorinated to prevent mosquito breeding. If you see mosquitoes breeding, then report it to Public Health – Environmental Health Services.
- Dress: Enjoy the outdoors?Wear protective clothing such as socks, shoes, light-colored, loose-fitting long pants and long-sleeved shirts when gardening, barbecuing, picnicking, camping or hiking.
- DEET: Don’t forget to use insect repellent containing DEET, picaridin, IR3535 or oil of lemon eucalyptus. Follow the product label instructions.
- Defend: Prevent mosquitoes from entering your home by ensuring doors and windows have tight-fitting screens that are free of tears and holes. If you notice an increase in mosquito activity around your neighborhood or workplace, report it to Public Health – Environmental Health Services.
Resources and Reporting
For mosquito and vector control information or services, contact SBCDPH EHS at 800-442-2283 or visit the Mosquito and Vector Control website. Dead or sick birds can be reported to 1-877-WNV-BIRD (1-877-968-2473) or at Westnile.ca.gov.
Additional County Update News – September 17, 2026
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