VENTURA, California – On September 5, 2025 the Ventura County Environmental Health Division (Division) received confirmation from the California Department of Public Health that a bird collected during the fourth week of August (8/25) from the Simi Valley area tested positive for West Nile Virus (WNV). WNV is established in Ventura County and additional WNV positives are expected. This is the first detection of WNV activity this year in Ventura County.
The Division monitors and controls mosquito breeding sources throughout Ventura County. All mosquito breeding sources in the area where the bird was collected will be inspected and treated if evidence of mosquito breeding is observed.
The Division also advises the public to take the following precautions to minimize exposure to WNV:
- Eliminate all standing water sources from your property.
- Ensure doors and windows have tight-fitting screens without holes.
- When outdoors, wear long pants and long-sleeved shirts and limit activity,
especially at dawn and dusk
- Use an EPA-approved insect repellent containing DEET, picaridin, oil of lemon eucalyptus, para-menthane-diol (PMD), or 2-undecanone.
WNV can not only affect humans but can also affect horses. For information on WNV in horses, the owners should contact their veterinarian.
To report any potential mosquito breeding sources in Ventura County, the public can call the mosquito complaint HOTLINE at 805/658-4310. The Division also provides mosquito eating fish to the public to use in non-maintained swimming pools, ornamental ponds, and similar water features.
To request mosquito-eating fish call 805/662-6582. To report wild birds that have died recently call the California Department of Public Health at 877/WNV-Bird (877/968-2473).
To obtain information about mosquito control and surveillance efforts in Ventura County please visit the Division’s website: https://rma.venturacounty.gov/divisions/environmental-health/vector-control-program/