Eleven Dallas County cities have decided to conduct aerial spraying for mosquitoes to fight the worst outbreak of West Nile virus in the United States this year.

More than 500 people in North Texas, including 217 people in Dallas County, have been diagnosed with West Nile virus. Ten people in Dallas County have died.

Addison, Carrollton, Coppell, Dallas, Farmers Branch, Garland, Grand Prairie, Highland Park, Mesquite, Richardson and University Park have opted for aerial spraying.

Dallas County Judge Clay Jenkins said aerial spraying would begin at 8:30 p.m. Thursday, weather permitting.

Two specially outfitted prop planes will spray a 49,000-acre area that includes University Park, Highland Park and parts of North and East Dallas.

Clarke Mosquito Control will conduct the spraying. Doug Carroll, of Clarke Mosquito Control, said the spraying would take between two and hour hours to complete.

Officials said that crews would spray less than 2 tablespoons of Duet pesticide per acre. Single droplets are too small to be seen by the human eye and can kill a mosquito, an expert said.

Carroll said crews spent Wednesday night mapping out the terrain in the first spray zone so the information could be loaded into the airplane’s computers.

"We have on-board computer systems in our aircraft that the pilots are monitoring," he said. "All this is inputted into the on-board computer systems. The pilots also fly with a military-grade night vision goggles."

Carroll also said the pilots would do a dry run on Thursday before going up again to do the actual spraying.

Judge Clay Jenkins has an 11:30 a.m. meeting on Thursday with at least a dozen other city leaders from South Dallas County to discuss the plans for attacking West Nile virus.

City officials with Cedar Hill, Duncanville, DeSoto, Glenn Heights, Ovilla, Lancaster, Wilmer, Hutchins, Balch Springs, Seagoville, Sunnyvale and Cockrell Hill are expected to attend.

Cedar Hill, Cockrell Hill, DeSoto, Irving, Lancaster, Rowlett, Sachse and Wylie have decided against aerial spraying.

Each city in Dallas County had the option to be included or not be included in the aerial spraying plan. Most cities in Texas are set up as home-rule cities, meaning they have the responsibility to decide on their own rules and ordinances that affect their citizens.

NBC 5's Ben Russell, Lindsay Wilcox, Frank Heinz and Amanda Guerra contributed to this report.