DALLAS -- For the first time in more than 45 years, planes took off Thursday night to spray insecticide over parts of the city to combat the nation's worst outbreak of West Nile virus, which has killed 10 people in Dallas County.

"I cannot have any more deaths on my conscience because we did not take action," Dallas Mayor Mike Rawlings said.

Although common in other major cities, aerial spraying provoked debate in North Texas between health officials trying to quell the disease risk and people concerned about insecticidal mist drifting down from above.

Because of the outbreak's severity, the Texas health department is stepping in to oversee and pay for the effort. The department has reported 17 deaths statewide.

"This year is totally different from the experience Texas has had in the past," state Health Commissioner David Lakey said. "If it's nuisance mosquitoes, we ask the city or county to pay part of that. But in the midst of this disease outbreak, it's easier for us to go ahead and do it."

Clarke, a national spraying company, deployed Beechcraft King Air twin-engine planes at 10 p.m. Thursday for three hours of spraying.

One countywide application costs about $1 million. A second application is possible if the first does not kill enough mosquitoes.

The chemical released from the planes, synthetic pyrethroid, mimics a natural substance found in chrysanthemums. The Environmental Protection Agency has said that pyrethroids do not pose a significant risk to wildlife or the environment, though no pesticide is 100 percent safe.

Most people infected with West Nile virus won't get sick, but about 1 in 150 people will develop the severe form of the illness.

Jordan Conner, 14, spent eight days in intensive care with the most severe form of West Nile virus. Her mother, Ebonie Conner of Arlington, said she doesn't approve of aerial spraying and wishes local leaders would do more to educate the community.

"We've been desensitized to West Nile virus," Conner said. "It's been ingrained in us that it affects older people and infants. I think they need to pass out insect repellent, mention it in back-to-school drives."

In Tarrant County

Aerial spraying is not yet planned in Tarrant County, where the number of reported West Nile cases jumped 20 percent between Monday and Thursday -- from 159 to 191 -- according to Tarrant County Public Health.

Two deaths have been attributed to the virus. Denton County has reported one death.

Several Tarrant County cities regularly send out trucks to spray from the ground. But until this week, Fort Worth hadn't sprayed for mosquitoes in more than 20 years.

Starting tonight, weather permitting, trucks will spray more than 38 miles of streets from just south of downtown into the Fairmount neighborhood for three nights.

Fort Worth officials organized an informational meeting for residents of the 76104 and 76110 ZIP codes Thursday night at the Fire Station Community Center, 1601 Lipscomb St.

North Richland Hills. Spraying is "something we do every year between May and October," said Mary Peters, a city spokeswoman. "We are not doing the mosquito traps or any of the testing. After numerous years in a row with positive results, we know the mosquitoes that carry the West Nile virus are here and they are not going anywhere."

Euless. Spraying has been done Monday through Wednesday for weeks.

Bedford. Spraying started this week from 10 p.m. to 4 a.m. Wednesday and Thursday in two areas. Go to bedfordtx.gov for more information. The Boys Ranch Activity Center is not included in the spraying. The city is counting on fish in the center lake to eat mosquito larvae and is using a larvicide in the drainage channel that cuts through the facility and feeds the lake.

A closer look

Reported cases of West Nile virus are rising in Tarrant County. Officials report that 60 mosquito pools have been reported across the county, with high concentrations in Hurst, Arlington and Westover Hills.

Sources: Tarrant County Public Health, North Central Texas Council of Governments 2012 population estimates

Staff writers Darren Barbee, Terry Evans and Mitch Mitchell contributed to this report, which leads with material from The Associated Press.

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