Omar Villafranca, NBC 5 News
Mosquitoes in Flower Mound and Garland have tested positive for West Nile virus.
The three human cases of West Nile virus reported in Dallas County this week are far from the hundreds reported last summer and are not close to the level to just aerial mosquito spraying, health experts and county officials said Friday.
County Judge Clay Jenkins, the county's top elected official, said county leaders are concerned about the human cases but some human cases were expected. There is not a certain numerical threshold that would trigger aerial spraying, he said.
"As far as like the elected officials having set out a specific line, they have not done so, nor would it be appropriate for elected officials to do that because none of us are scientists," he said.
Jenkins said he and other county leaders frequently consult with Dallas doctors, as well as specialists in the county and state health departments and the Centers for Disease Control and Prevention.
Jenkins said gathering data and opinions from scientists and medical professionals shapes the decision on when and where to launch aerial spraying against the mosquitoes. Jenkins stressed the scientific community isn't sounding any alarms.
"I don't have any scientists right now saying to me, 'You know, put planes in the air. We need to start aerial spraying,'" he said. "If we don't have a fierce, all-over-the-county problem like we did last year, there is not a need to spray from the air if we can handle it on the ground."
Dr. John Carlo, chairman of the Dallas County Medical Society Emergency Response Committee and a former Dallas County health department medical director, said last year was much different from this year's mosquito season.
"What happened last year was, we saw an evolving risk with numbers of human cases that kept continuing to ramp up," he said. "Thankfully, this year, we haven't seen that. But we're not done yet."
Carlo was among the experts who urged Dallas County to conduct aerial spraying last year but is not calling for it this year.
He praised the county's expanded monitoring system, which uses far more mosquito traps to better detect infected mosquitoes.
"That offers a better way to make targeted intervention," he said.
This year, the county has used targeted ground spraying to kill mosquitoes. A team of experts constantly monitors the situation, Jenkins said.
"Things can change suddenly, and that's why we look at this every day," he said. "But we're in a much better point than we were last year, and we think can continue handling this with the assets we have on the ground right now and, if that changes, we'll let the public know."
Earlier this year, county commissioners approved a budget for possible aerial spraying. Dynamic Aviation, which conducted last year's aerial spraying, told NBC 5 that the county has an contractual option with the company to continue spraying if needed.
Spokesman Caleb Stitely said Dallas County leaders have contacted the company to keep them up-to-date on West Nile virus numbers, not to mobilize the company.
Jenkins is urging residents to continue removing standing water that can serve as mosquito breeding areas and wear insect repellant and long sleeves in the dawn and dusk hours, when mosquitoes are active.