The California Department of Public Health has confirmed the West Nile Virus has been isolated from mosquitoes collected in the City of Pismo Beach. The positive mosquitoes were collected on July 9th and 10th at the city’s Chumash Park.
The West Nile Virus was isolated from the mosquito species Culex tarsalis. The Culex tarsalis mosquito is commonly found in California, including the central coast region.
The mosquitoes were collected by staff from the Mosquito and Vector Management District of Santa Barbara County, which does mosquito abatement and surveillance work for the city via a special services contract.
The District followed up with a treatment of the creek and two freshwater ponds at Chumash Park on July 18th with the biological insecticide BTI (Bacillus thuringiensis israelensis) that is specific to mosquito larvae and does not harm birds, fish, frogs, or other types of insects. Also on July 18th, Pismo Creek and the following mosquito breeding sources at Pismo State Beach were similarly treated: Pismo Ecological Reserve, North Beach Campground, LeSage Riviera Golf Course, and Oceano Campground. The MVMD will plan on returning in early August to do more trapping, inspection, and treatment for mosquitoes in the City of Pismo Beach and at Pismo State Beach.
As the warm weather continues, it presents advantageous breeding conditions for mosquitoes. Because mosquitoes spread disease such as West Nile Virus, the public is encouraged to eliminate breeding places for mosquitoes in and around residences and the workplace. In California this year, there have been four confirmed human cases of West Nile Virus (one case each in Glenn and Sacramento.