According to a statement from the district, it has been receiving as many as 50 daily reports of dead birds, 13 testing positive for the virus. Mosquitoes that have fed on infected birds can pass West Nile to other birds, humans, horses and other animals.

Nearly 250 human cases of West Nile have been reported in California this year, six of which were fatal. No human cases have been reported in Santa Clara County.

Though most people infected with the virus show mild or no symptoms, approximately 1 percent—usually people who are elderly or have immune-system deficiencies—require hospitalization.

Vector control scientific-technical services manager Noor Tietze said county residents should still call the district or a special dead-bird hotline to report crows, raptors, sparrows and finches that have been dead less than 48 hours. But due to the high volume of calls, the county will not be able to pick up all of them. If residents are instructed to dispose of the birds or if the birds are not picked up by 3 p.m. on the day they are reported, the birds should be handled with caution.

The district's statement advises handling the birds using only gloves or multiple heavy-duty plastic bags. The birds should be double-bagged, and the bags should then be tightly sealed and placed in a covered trash can.

Though it is not believed humans can get the virus from birds, Tietze said state officials have still recommended that people handling them be careful.

"There's some thought that ... there may be bird-to-bird transmission of West Nile virus, so just to eliminate any potential, human contact needs to be minimized with the bird," he said.

The district also recommends keeping mosquito populations down by eliminating standing water that can serve as a breeding ground.

To report a dead bird, contact the California Department of Health Services at 877.968.2473 or the vector control district at 408.792.5010 weekdays before 3 p.m. For more information about West Nile virus, visit www.sccvector.org.