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2-week delay expected before W. Nile cases fall

Profile image for By John D. Harden / Staff Writer
By John D. Harden / Staff Writer

Denton County Health Department officials expect a two-week delay before seeing a decrease in the amount of human West Nile virus cases, following a three-day, countywide spraying by a mosquito control company.

According to the health department, it will take several weeks to get the official report on the aerial pesticide’s effectiveness, but preliminary reports from mosquito control company Clarke estimate a 70 to 90 percent mosquito kill.

In Dallas County, the area saw a 93 percent effective rate.

Bob Martinez, the emergency preparedness coordinator for the health department, said additional data should be available by next week.

“We are waiting on mosquito trappings that occurred after the spraying to help determine the effectiveness of the aerial spraying,” he said. “There are currently no plans to do another round of aerial spraying. We will continue with disease investigations and reporting new human cases.”

County Judge Mary Horn declared a health emergency two weeks ago after a number of county residents were diagnosed with West Nile virus. Horn allowed county municipalities to opt out of the aerial spray. Thirteen of 44 municipalities opted out.

Four planes were used to spray the county with Duet, a pesticide that targets adult mosquitoes.

Clarke and Dynamic Aviation sprayed the county Friday, Saturday and Sunday nights. A total of 282,800 acres were sprayed twice over the three-night period. Gusty winds forced officials to postpone their aerial treatments twice, but all target areas were treated, emergency management officer Jamie Moore said.

In addition to the spray, the health department is distributing 5,000 cans of DEET insect repellent in an ongoing effort to prevent West Nile virus infections. The cans, which were donated by insect repellent company Cutter, are available at various locations around the county.

Martinez said he expects the amount of human cases to drop in two weeks because cases reported are normally based on exposure that occurred seven to 14 days prior.

As of Tuesday afternoon, the health department had reported 77 positive mosquito pools and two West Nile virus-related deaths among the 148 human cases of the virus — 103 of those cases were diagnosed as West Nile fever, which has milder symptoms, and 45 diagnosed as the more serious neuro-invasive disease.

JOHN D. HARDEN can be reached at 940-566-6882. His email is .


Residents can claim one free can of insect repellent per household at the following locations:

•  Denton County Health Department, 535 S. Loop 288, Denton

•  Denton County Health Department, 190 N. Valley Parkway, Suite 203, Lewisville

•  Sandy Jacobs Government Center, 1029 W. Rosemeade Parkway, Carrollton

•  Steven E. Copeland Government Center, 1400 FM424, Cross Roads

•  Mary and Jim Horn Government Center, 1505 E. McKinney St., Denton

•  Roanoke Government Center, 876 N. U.S. Highway 377, Roanoke

•  The Colony Government Center, 6307 Main St., The Colony