STOCKTON — The San Joaquin County Mosquito and Vector Control District last week said it has found mosquitoes positive with West Nile Virus for the past four consecutive weeks in the Tracy area.

Last week alone, the district said, two positive mosquito samples were found in the 95376 and 95377 ZIP codes.

The first reported WNV detection of the year in the county was found in the former ZIP code on June 20. Since that time, 11 of 13 positive mosquito samples — or 84% — were detected in the two ZIP codes, the district said.

In addition, a crow from the Tracy area was the first dead bird in the county to test positive for the virus in the first week of the month.

“Detections of WNV in both birds and mosquitoes indicate there is active transmission occurring in the area,” district assistant entomologist Sumiko De La Vega said.

The district said 19 state-certified mosquito control technicians check as many as 300 known mosquito sources in their designated areas of operation every seven days and respond to service requests from the public.

More than 80 surveillance traps are placed weekly to biweekly to assess the mosquito populations and test samples for diseases, and the district is spraying for adult and larval mosquitoes by ground and air in areas where high populations have been found, or in areas of WNV concern.

Residents can receive spray notifications by signing up for the district’s email notification system www .sjmosquito.org.

The district said it will soon be sending second “Notice” letters to suspected neglected swimming pool homeowners, followed by a visit from a technician, and if necessary, a warrant to inspect and treat neglected swimming pools.

Dirty pools serve as a primary breeding ground for mosquitoes that vector WNV.

“Rest assured that the district enhanced all resources available to reduce the risk of West Nile Virus in the human population,” district spokesman Aaron Devencenzi said. “The district will continue to implement the California Mosquito-Borne Virus Surveillance and Response Plan to protect the public health and welfare.”

The district is encouraging residents to protect themselves from mosquito bites and the risk of WNV infection by eliminating all sources of standing water on your property that can support mosquito development, including a bottle cap of water.

Apply insect repellent containing EPA-registered active ingredients, including DEET, Picaridin, Oil of lemon eucalyptus, or IR3535 when outdoors and try to avoid spending time outside when mosquitoes are most active, which is typically at dawn, dusk, and into the evening. If you do go outdoors, it is recommended you wear long pants, long-sleeved shirts, and other protective clothing.

You can also keep mosquitoes out of your home with tight-fitting screens on doors and windows, the district said.

Contact your veterinarian for information on vaccinating equine against WNV.