West Nile virus-positive mosquito samples in Orange County have more than doubled in a single week, jumping from 18 to 38, with Newport Beach now one of 13 cities where infected mosquitoes have been confirmed.
The Orange County Mosquito and Vector Control District reported the surge as of July 8. Miquel Jacobs, the district's director of communications, confirmed the county is "above-average for this time of year." Newport Beach has recorded one positive sample so far this season, following the district's first detection of virus-carrying mosquitoes in the city in early June.
The numbers mark a dramatic departure from recent years. In all of 2025, the district found West Nile virus in just four mosquito pools countywide. In 2024, it was five. In 2023, only one. This year has already reached 38.
The surge tracks with warnings OC Vector Control issued months ago. In March, spokesperson Brian Bannon said heavy rains followed by sudden heat had given mosquitoes a head start on breeding. "Unfortunately, what it could be setting us up for is a really bad summer," he said.
Where the virus has been found
Fullerton leads the county with 15 positive samples, accounting for nearly 40% of all detections. Buena Park follows with seven, then Anaheim and Santa Ana with three each. Huntington Beach has two. Newport Beach, Brea, Costa Mesa, Cypress, Garden Grove, Seal Beach, Stanton, and Westminster each have one.
The district announced truck-mounted mosquito spraying in a 4.5-square-mile area of Fullerton from Friday, July 10, through Sunday, July 12, between 1 a.m. and 5 a.m. each night. No similar treatment has been announced for Newport Beach.
National context
The spike is not limited to Orange County. As of June 30, the CDC had recorded 48 human West Nile cases nationwide, the highest number reported in June since 2004. Nearly 80% involved neuroinvasive disease. West Nile activity has been reported in 23 states, the most this early in a decade.
California has confirmed one human infection in 2026: a Long Beach resident hospitalized with neuroinvasive illness. No human cases have been reported in Orange County.
Prevention recommendations
OC Vector Control recommends eliminating standing water around homes, repairing window and door screens, and using insect repellent with DEET when outdoors. According to the district, the southern house mosquito needs a larger body of water to breed, but the ankle-biter mosquito species can breed in as little as a capful of water. The district recommends repellent with 30% DEET specifically for ankle biters.
People over 50 and those with preexisting health conditions face higher risk of serious illness. About 1 in 5 people infected develop mild symptoms such as fever, body aches, and nausea. About 1% develop neuroinvasive disease, and roughly 1 in 10 people with severe West Nile illness die, according to the CDC.
Residents can request a free property inspection from OC Vector Control staff, who will identify and help eliminate mosquito breeding sources. Requests can be made at ocvector.org.
