City leaders approved a resolution Tuesday authorizing ground spraying after hearing an update on the mosquito traps and reports of human cases of West Nile virus in Denton.
Late last week, a second human case of the mosquito-borne disease was reported in Denton, in a resident who lives in a neighborhood near Wiggly Field Dog Park.
A city crew will spray the south Denton neighborhood beginning at around 10 p.m. Thursday and finishing at about 3 a.m. Friday, weather permitting.
Trucks will spray an area bounded by Teasley Lane on the east, by Hickory Creek Road on the south, by Ryan Road on the north, and on the west by Brisas Court, Aqueduct Drive and Parkhaven Drive.
In the case of rain or windy conditions, the city plans to spray Friday night into Saturday morning instead.
Four human cases of West Nile virus have been reported in Denton County this year, with two in Denton and two more in Flower Mound. Only one of those four cases has seen the patient contract the more serious neuroinvasive version of the disease, according to officials at the Denton County Health Department.
The city’s decision came during a special called meeting Tuesday afternoon after some deliberation, as Denton has had only a single pool of mosquitoes test positive for the virus out of more than 600 traps deployed this year.
In addition to traps that collect samples for analysis at the state lab, the city and researchers at the University of North Texas have used this year a second kind of trap, called ramps, which can be screened more quickly. So far, in both kinds of traps, only a mosquito sample collected on Oct. 1 at Robson Ranch has tested positive for West Nile virus.
UNT professor Jim Kennedy told the City Council that after human cases are reported, traps are routinely moved into the areas nearby. Another resident who lives near North Lakes Park contracted the virus in June, but no trap there turned up positive. Nor has any trap around Wiggly Field tested positive. The city routinely traps at an assisted living facility near there.
Far fewer mosquitoes have been caught in the city’s monitoring traps since the weather has gotten colder, Banks said. The number of Culex quinquefasciatus, the mosquito that carries the virus in this area, in those traps has been very low in the past two weeks, he said.
Last year, in one of the worst outbreaks of West Nile virus Denton has seen, 54 of the 476 mosquito traps collected from May 16 through Nov. 6 tested positive. Of the 36 human cases reported in Denton in 2012, the last case was reported on Nov. 12 and was thought to have been contracted on Oct. 11.
On average, the first freeze occurs prior to Dec. 4, Banks said, which typically signals the end of the season for West Nile.
PEGGY HEINKEL-WOLFE can be reached at 940-566-6881 and via Twitter at @phwolfeDRC.