Mosquitoes aren’t welcome in Oakley. 

The Contra Costa County Mosquito and Vector Control District used truck-mounted ultra-low volume equipment Monday night to control adult mosquitoes due to a high number of the insects in the area and the detection of West Nile virus. 

The treatment took place between dusk (approximately 8:30 p.m.) and 11 p.m.

The area treated is bordered on the north by Big Break/San Joaquin River; on the south by railroad tracks; on the east by Fetzer Lane, and on the west by Piper Lane above Rutherford Lane. 

The public health pesticide used is Zenivex E4 RTU applied at a rate of 1.5 ounces per acre by truck-mounted ultra-low volume equipment. 

The district said Friday two groups of mosquitoes have tested positive for West Nile virus in Oakley. Also, four dead birds have tested positive for the virus and antibodies were detected in five sentinel chickens. 

An East Contra Costa County man died from West Nile virus on July 16, marking the first death from the disease reported in the county since 2006.  

“The presence of WNV-positive mosquito samples, dead birds, and sentinel chickens in Oakley indicates an elevated risk currently exists for residents and visitors in that area,” said Steve Schutz, scientific program director for the vector control district. 

Birds can become infected with West Nile virus, and when a mosquito feeds on an infected bird, the mosquito can become infected. An infected mosquito can spread the virus to a human or other animal through a single bite. The infection can be dangerous to humans, with symptoms such as fever, headache, vomiting, or rash. 

To reduce the risk of mosquito bites, the district recommends using U.S. Environmental Protection Agency-registered insect repellents containing at least one ingredient such as DEET, Picaridin, the repellent version of oil of lemon eucalyptus, or IR3535. 

The district uses an integrated vector management program, meaning it uses a variety of protocols for controlling mosquitoes. These protocols include public education, physical control including managing vector habitat, biological control such as mosquitofish, and chemical control such as public health pesticides.  

The majority of the district’s mosquito control is completed when mosquitoes are still in their aquatic form, in their water source. Once mosquitoes emerge from the water as adults, the only effective method to control them is by adult mosquito control.