Follow CBSDFW.COM: Facebook | Twitter

DALLAS COUNTY (CBSDFW.COM) — In an effort to decrease the risk of West Nile Virus, Dallas County is spraying several cities for mosquitoes this week.

READ MORE: 'It Looks Pretty Dang Busy:' North Texas Airports Brace For Busy Holiday Season

“While we have not had any human cases of West Nile virus reported to date this season in Dallas County, we have had some positive mosquito traps,” said Zachary Thompson, Dallas County Health and Human Services director. “It’s best to knock down the mosquito population as much as possible to help eliminate an increased risk of human exposure to West Nile virus.”

Crews will be out in Desoto and Lancaster Sunday night.

READ MORE: 'Heading Home Today Empty Handed:' Aaron Tschritter Passed Away In Dallas Car Crash, Sister & Wife Say

Officials urge residents to remain inside while sprayers are in the area between 9pm and 5am.

Balch Springs, Seagoville, and Wilmer neighborhoods are scheduled to be sprayed Monday night.

Seagoville and Wilmer will be sprayed a second time on Friday night.

MORE NEWS: Update: Sister & Wife Say Aaron Tschritter Passed Away In Dallas Car Crash

(©2015 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)