Mosquitoes show up, but West Nile skips Mansfield

By Amanda Rogers

Mansfield Record

Less than a week before Halloween and the only blood suckers in sight are the same ones that have been tormenting us all summer – mosquitoes.

But this year, the little vampires didn’t bring West Nile Virus to haunt Mansfield. For the first time in years, no mosquitoes in Mansfield have tested positive for the mosquito-borne virus that has no effect on some humans, but can prove fatal in others.

Numbers of infected mosquitoes are also down in surrounding cities, said Tony Sanchez, Mansfield’s environmental services public health specialist.

“Arlington had two positives, Bedford had one, Burleson had three, Fort Worth had one and Grand Prairie had six,” he said.

“We haven’t had a positive for West Nile in 2022,” Sanchez said. “We had 30 West Nile events last year in Mansfield.”

The city has six traps set throughout Mansfield, which are rotated to different areas. The traps are checked weekly and the mosquitoes tested by Tarrant County Public Health. And no matter how many mosquitoes we swat, Mansfield has a city policy that it will not spray for mosquitoes unless one tests positive for West Nile. When the city does spray, it is only in the area of the positive test.

The city does keep a close eye out for the virus because it can be deadly for humans.

“West Nile is one of the highest rates of mosquito-borne illnesses in US,” Sanchez said. “Unfortunately most don’t feel sick. Some develop flu-like symptoms, 1 in 5 get a fever, 1 in 150 develop serious illnesses that can sometimes be fatal. There is no vaccine.”

Nina Dacko, an entomologist and vector control supervisor with Tarrant County, believes she knows why West Nile hasn’t been as prevalent this year – because the birds are becoming immune.

“West Nile Virus is very complex,” Dacko explained. “Birds can pick up the virus and then the mosquitoes bite the bird and pass it one.

Many birds will die of the virus, she explained.

“A sign of West Nile is dead crows and blue jays,” Dacko said. “Birds can become immune, and birds that recover have lifelong immunity.”

She says that the 72-day drought this summer helped, too, since the mosquitoes didn’t have as much standing water to breed.

“There are so many variables,” Dacko said. “The combination of drought and a high proportion of birds with immunity kept West Nile at bay.”

But like zombies, look for West Nile to return once the birds with immunity die and more birds without it are out there to pass on the virus from one mosquito to the next.

Many cities, like Mansfield, do not spray unless a mosquito tests positive for West Nile, Dacko said, because there is a risk that the mosquitoes could become immune to pesticides.

Sanchez points out that homeowners can help.

“There are certain things we can do to keep mosquitoes from proliferating,” he said. “Mowing, getting rid of standing water, trimming grass and bushes, and wear mosquito repellent and long sleeves and pants.”

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