Denton County officials say the continually growing number of West Nile virus cases is the reason for a county health emergency declaration and imminent aerial spraying to combat the outbreak.
Officials are waiting on responses from Denton County cities to see what municipalities want to be sprayed and which do not, so they can give the word to state officials who then can begin the next phase of fighting the virus.
During a Thursday news conference, Bing Burton, the Denton County Health Department director, said there were six new cases confirmed Thursday, bringing the total to 118, including one death. He believed that to be the highest per capita in the state.
“It’s a dubious honor we’re not real proud of,” Burton said.
Of the county cases, 82 have been diagnosed as West Nile fever, while 36 were found to be the more serious neuro-invasive disease.
Burton said the previous calculation of 16 cases per 100,000 people would have to be adjusted to factor in the new cases.
He said officials are not taking the virus lightly.
“Many of those people will fully recover; for many it will be a life-changing event,” Burton said.
He said municipalities have been doing a good job of ground spraying, and the aerial spraying would just add to those efforts.
Decisions on spraying unincorporated areas have not yet been made, Burton said.
Spraying would take place between 9 p.m. and 2 a.m. from planes that would fly out of Denton Airport. Spraying could begin as early as Thursday, but it depends on how quickly cities are able to pass their decisions along to the Commissioners Court.
Pilot Point officials already have approved spraying there, while Providence Village and Shady Shores leaders have said they do not want to be sprayed.
County Judge Mary Horn said officials are hoping to have a list of cities opting in at the next news conference, scheduled for 3 p.m. Tuesday in the Commissioners Courtroom.
City officials in Denton have not yet scheduled a meeting to discuss whether to request aerial spraying.
The county will use Clarke, which is the same pesticide company Dallas County used, to oversee its aerial operation.
University of North Texas biology professor James Kennedy, who supervised the study that first detected West Nile virus in Denton County in 2002, couldn’t say whether aerial spraying would have an effect on the virus this year because “the horse is already out of the barn.”
Kennedy also supervises the city’s monitoring program. From the first traps in May, mosquitoes were testing positive for West Nile. It wasn’t until the first week of August that the city had its first week where none of the traps — the UNT crew sets out about 40 all around the city where problems are known — held West Nile-positive mosquitoes.
“In the last couple of weeks, only one site, or two, showed up positive,” Kennedy said.
Denton has seen a decline in the virus in the traps just as Dallas County began its aerial spraying program, he said.
While evidence of the effectiveness of spraying could be argued either way, he says the recent decline in positive mosquitoes is more likely explained by the very hot weather during that time.
Biologists know that Culex quinquefasciatus, the mosquito species that carries West Nile in this area, doesn’t do well in extreme heat. They also know the insect overwinters in culverts and under bridges, Kennedy said. Last winter was mild, with only a few frosts and freezing days, and the mosquitoes were out early.
Spraying in those areas where mosquitoes are known to overwinter could be more efficient, he said.
“We don’t do that currently,” Kennedy said.
Pilot Point resident Buddy Cole, who suffers from chronic obstructive pulmonary disease, is less concerned about the pesticide in the spray than the spraying itself, which is atomized into droplets so small it takes more than 800 of them to line up an inch long.
“DEET for protection is OK, but breathing the spray is not,” Cole said in an e-mail. “It does come in wipes or [you can] get someone to spray a cloth for you if you have breathing problems.”
Jody Gonzalez, Denton County’s emergency management coordinator, said he thinks the spray, which has been ruled harmless to pets and people, will indeed work well against the mosquitoes and the spread of the virus.
“Based on what the state told us previously and what we were told today, one night of aerial spray is as good as 40 spray trucks,” Gonzalez said.
He said the planes would use the same pesticide that ground sprayers use, but in a more diluted form.
Horn said the county is trying to stay ahead of the virus outbreak.
“This is something to be taken serious, and I certainly do,” she said. “Hopefully this proactive approach will lessen the impact to Denton County citizens.”
Staff writer Peggy Heinkel-Wolfe contributed to this report.
BJ LEWIS can be reached at 940-566-6875. His e-mail address is firstname.lastname@example.org .
HOW AERIAL SPRAYING WORKS
Twin-engine Beechcraft B90 planes will fly predetermined grid patterns at an altitude of about 300 feet and at a speed of 170 mph. From two 100-gallon tanks mounted inside the plane, pesticide flows into tubes mounted in the airplane’s wings. An atomizer smashes the pesticide into droplets 30 microns wide, tiny enough to get past the tree canopy. The spray system is computer-guided, distributing the chemicals in 1,000-foot swaths at a rate of about 0.8 ounces per acre.
SOURCE: The Dallas Morning News.
Health experts recommend taking these steps during aerial or ground spraying:
• Stay indoors if possible and close windows.
• Consider keeping pets inside while spraying occurs.
• If outside or in a vehicle, be alert for the spraying truck and maintain a safe distance.
• If skin or clothes are exposed, wash them with soap and water.
• Rinse homegrown fruits and vegetables with water as a precaution.
• Cover small ornamental fish ponds.
• Because the chemical breaks down quickly in sunlight and water, no special precautions are suggested for outdoor swimming areas.