Tarrant County Public Health officials raised the possibility Tuesday that aerial spraying of mosquitoes may eventually be needed to combat the growing West Nile threat across the region.
The aerial spraying would be needed only if other methods are ineffective, officials said.
“We’re starting the discussion with our commissioners but really we’re encouraging local homeowners to start adding strategies to their toolbox,” Tarrant County Public Health Director Vinny Taneja said.
Besides getting rid of standing water on their property, using larvicide and wearing mosquito repellent, Taneja said homeowners may consider using sprays or foggers to fend off mosquitoes. Typically those sprays aren’t recommended, but in areas thick with mosquitoes, officials are suggesting the sprays to create a “residual barrier” around the home.
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“It is a last step, a last resort,” Taneja said. “It’s a fine balance. You don’t want to overuse it.”
Three Tarrant County residents have tested positive for West Nile. All have been confirmed to have the more serious neuro-invasive form of the virus.
We’re starting the discussion with our commissioners but really we’re encouraging local homeowners to start adding strategies to their toolbox.
Tarrant County Public Health Director Vinny Taneja
Ground spraying has been taking place across North Texas, but the number of mosquitoes carrying West Nile is at a high level. Through July 29, Tarrrant County had tested 2,770 mosquito samples with 238 coming back positive.
“Adult mosquito spraying is not having the intended effect,” Taneja told county commissioners. “One option is for aerial spraying. It’s a very expensive option.”
2012 is worst year on record
To spray the entire county by air would cost about $1 million and it would likely take two or three applications to be effective, Taneja said.
He also raised the possibility of targeted aerial spraying for areas with the highest concentrations of positive West Nile traps, which would run about $350,000 for each spraying.
The last time the county did aerial spraying was in 2012, which is considered the worst year on record for West Nile.
West Nile spreads when Culex mosquitoes bite infected birds and then bite humans.
Texas led the nation with 1,868 West Nile cases in 2012, including 89 deaths. The epidemic was worst in Dallas County, which recorded 398 cases and 20 deaths, and Tarrant County, which had 280 cases and 11 deaths.
Last year, Tarrant recorded 30 human cases and one death. Across Texas, there were 275 confirmed human cases of West Nile and 16 deaths.
While the county does the spraying, it is up to each city to decide if it wants to be sprayed.
Aerial spraying is not without controversy.
$1 million The cost to spray all of Tarrant County by air
Some critics are concerned that spraying could harm the environment and pose a threat to pets and bees. Too much spraying could also lead to pesticide-resistant mosquitoes.
Dallas County OKs aerial spraying
Last month, Dallas County commissioners approved aerial spraying to help prevent the virus’ spread.
So far, no aerial spraying has been done there, but Zachary Thompson, the county’s Health and Human Services director, said officials can respond quickly if needed to prevent another epidemic like in 2012.
Dallas County has 14 confirmed West Nile cases. Denton County has three confirmed cases.
“I think we just needed to put the motion on the table in terms of having planes ready if needed,” Thompson said. “The commissioners court authorized us to contact cities to obtain a letter of interest. Some have expressed interest but none are ready to go.”
One unanswered question is whether West Nile is close to peaking since the season appears to be running ahead of previous years. If it is close to peaking, Thompson said, aerial spraying may not be needed.
“We’re looking at it daily and some of the cities think they can manage it with ground spraying,” Thompson said. “It’s when they can’t manage it with ground spraying that we need to go aerial spraying.”
Concerns about Zika
Neither ground nor aerial spraying will help with the Zika virus, a cause of increased concern.
Zika is transmitted by the Aedes mosquito, which bites in daytime and thrives indoors.
West Nile is carried by the Culex mosquito, which bites at night and is found primarily outdoors.
There has been no local transmission of Zika virus in Texas, but concerns have increased since it was confirmed that Zika is now being locally transmitted in Miami.
“It’s not if but when,” Thompson said. “It’s going to get to Texas at some point.”
Tarrant County has recorded 14 imported Zika cases while Dallas had 22. The most recent Tarrant County case, which was confirmed on Tuesday, involved a person who had traveled to Grenada, where the virus has spread locally.
Combating Zika is much more labor-intensive, Taneja said. It requires public health officials to go door to door and survey each home where a confirmed Zika case has been found.
It’s not if but when. It’s going to get to Texas at some point.
Dallas County Health and Human Services Director Zachary Thompson
“The idea behind that is to be aggressive and it should not get a hold in our population,” Taneja said.
On Tuesday, the Centers for Disease Control and Prevention awarded $720,000 to Texas to set up programs to rapidly detect microcephaly, a birth defect that affects the brain and has been linked to the Zika virus. The CDC has advised pregnant women to delay travel to the Miami area.
Preventing mosquito bites
Wear long-sleeved shirts and long pants, especially at dawn and dusk.
Regularly drain all standing water. Mosquitoes can lay eggs in as little as a tablespoon of water.
Use an approved insect repellent (containing DEET, picaridin, IR3535 or oil of lemon eucalyptus).
West Nile virus symptoms
Neuroinvasive disease: Neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. This form can be deadly.
Zika virus information
Tarrant County Public Health’s Zika hotline is 817-248-6299 or access.tarrantcounty.com (click on government, then public health)