Two Manteca birds are the first confirmed Northern San Joaquin Valley cases in 2012 for the deadly West Nile virus.

The San Joaquin County Mosquito and Vector Control District Thursday received confirmation that a common raven and a yellow-headed black bird have tested positive for West Nile virus (WNV). Both dead birds were collected in Manteca.

The birds are the first sign of West Nile virus activity in the area for the 2012 season.

“Finding the first positive birds is significant because it means that the virus is present in our area” said John Stroh, District Manager. “With the very mild winter and the warm temperatures we’ve had so far, it’s not unusual to find positive birds at this time of year.”

Dead birds provide an early indication of where positive mosquito samples may also be found and where human cases may develop later in the season.

The public is encouraged to report dead birds by calling the California Department of Public Health hotline at 877-WNV-BIRD (877-968-2473). Some species of birds such as crows, jays and magpies are very susceptible to the virus and are more likely to die from the infection.

Though not all birds that are reported will be picked up and tested, the reports provide valuable information and assist with mosquito surveillance and control efforts that help protect public health. Birds are hosts for WNV and mosquitoes that transmit the virus by biting an infected bird and then biting a person or other animal.

With recent wet weather in the area, the District also reminds the public to drain after the rain.

“Please look around your yard and dump out water in any containers that might breed mosquitoes,” Stroh said. “It only takes a few minutes, but it goes a long way in preventing mosquitoes later in the season.”

In 2011, nine deaths and 158 human WNV cases were reported in California.

To report a neglected swimming pool or other mosquito breeding problems,call 1-800-300-4675 or fill out a service request online at www.sjmosquito.