The area west of Interstate 15, north of Adams Avenue, east of 36th Street and south of Alexia Place is the third to be sprayed in an attempt to prevent Zika from spreading to Aedes mosquitoes, which are capable of transferring tropical diseases to humans. The spraying began at 9 a.m. and was scheduled to run until about 5 p.m.
Unlike native mosquitoes, the Aedes type likes to live in and around homes and will bite during the daytime, instead of dawn or dusk. They were first found locally in 2014.
So far, no infected Aedes mosquitoes have been found in the San Diego region or elsewhere in California, according to county health officials. All of the 30-plus cases of Zika in the San Diego region resulted from travel to areas where the disease is prevalent.
The Zika virus began drawing attention earlier this year when some infected pregnant women gave birth to babies with microcephaly, which causes heads and brains to be smaller than normal. The 20 percent of infected people who actually get sick usually experience only mild symptoms, according to county officials.
A precautionary spraying was conducted in South Park last month. Vector control workers met with some protests during a similar effort earlier this week in the Mount Hope neighborhood.
The pesticide used by the county, Pyrenone 25-5, is derived from chrysanthemums and is not the same insecticide that killed millions of honeybees last week after aerial sprayings in Florida and in South Carolina. County officials say Pyrenone 25-5 poses low risks to people and pets and dissipates in roughly 20-30 minutes.
However, area residents who want to minimize their exposure can take precautionary steps, including:
-- staying inside and bringing pets indoors if possible;
-- closing doors and windows;
-- turning off fans that bring outdoor air inside the home;
-- covering ornamental fish ponds to avoid direct exposure;
-- rinsing fruits and vegetables from gardens with water before cooking or eating;
-- wiping down or covering outdoor items such as toys; and
-- covering barbecue grills.
County officials also issued a reminder to residents to help control mosquitoes themselves.
"It's really important for people to inspect in and around their homes and dump out any standing water that can give these mosquitoes places to multiply," said Rebecca Lafreniere, deputy director of the county Department of Environmental Health. "They can breed in the trays under flower pots, in holes in trees, in kids toys on your lawn that can collect sprinkler water -- anything that can collect water."