Frequently Asked Questions

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Mosquito-borne diseases are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. They can transmit the illness without being infected themselves.

Have any of the Viruses been Detected in Keller?
Mosquitoes collected from five traps around the city are tested weekly by the Tarrant County Public Health Department for West Nile Virus and Saint Louis Encephalitis Virus. 

There has been 1 positive mosquito test for West Nile Virus in 2019.

 Week  Trap Location(s) Ground Spraying Dates
Aug. 12  7000 Shady Grove Road  Aug. 15 & 16 

Additional Suggested Resource: Tarrant County Public Health West Nile Virus Information

How will I be Notified of a Mosquito-Borne Human Cases this Year?

As part of the city’s Mosquito Abatement Program, we work with the Tarrant County Public Health Department to alert our residents and businesses of any confirmed cases of a mosquito-borne diseases within the city’s borders. 

If any mosquito trapped within the Keller city limits tests positive for West Nile Virus or Saint Louis Encephalitis Virus - or if the city is notified of any confirmed human cases that have been transmitted locally (signifying its presence in the local mosquito population) - notification will be posted on the city’s website and social media accounts.

Have there been Human Cases of Mosquito-Borne Illnesses in Keller this Year?

There have been no human cases of West Nile Virus confirmed by the Tarrant County Public Health Department in 2019.

What is the City Doing to Prevent the Spread of Mosquito-Borne Illnesses?
For a look at the city’s Mosquito Abatement Program, click HERE.

Is the City Considering Aerial or Ground Spraying at this Time?
When it comes to ground spraying, the City of Keller follows recommendations from the Tarrant County Public Health Department. Typically, that recommendation is to spray within a 1/2-mile radius of any trap where a mosquito tests positive for the West Nile Virus or Saint Louis Encephalitis Virus. 

What Sort of Spray is Used During Ground Spraying?
Our contractor uses water-based insecticides that offer low toxicity, low odor, rapid biodegradation and high mosquito mortality. Spraying generally takes place between 9 p.m. and 5 a.m. while mosquitoes are active and winds are slow.

What Can I do to Protect Myself and My Family From a Mosquito-Borne Disease?
The easiest and best way to avoid a mosquito-borne disease is to prevent mosquito bites, which can be accomplished by eliminating breeding grounds and adult mosquitoes on your property, as well as actively protecting yourself and your family against bites when you are outside. Pregnant women should consult with their health care provider if they decide to travel. For a full list of tips, visit the following pages: 

What are the Symptoms of a Mosquito-Borne Virus?

No Symptoms in Most People - Approximately 80 percent of people who are infected with West Nile Virus will not show any symptoms.

Milder Symptoms in Some People - Up to 20 percent of the people who become infected have milder symptoms that can last for as short as a few days, though even healthy people have become sick for several weeks. These symptoms include:
• Fever
• Headache
• Body aches
• Nausea
• Vomiting
• Swollen lymph glands
• Skin rash on the chest, stomach and back

Serious Symptoms in a Few People – about 1 in 150 people infected with West Nile Virus will develop severe illness. These symptoms may last several weeks, and neurological effects may be permanent. Severe symptoms can include:
• High fever
• Headache
• Neck stiffness
• Stupor
• Disorientation
• Coma
• Tremors
• Convulsions
• Muscle weakness
• Vision loss
• Numbness
• Paralysis

Additional Suggested Resource: Centers for Disease Control and Prevention West Nile Virus Fact Sheet

Do Mosquitoes Breed in all Bodies of Water?
No, not all bodies of water serve as abundant mosquito-breeding areas. Ponds with steep banks that are relatively free of organic matter and have little or no vegetation extending into the edge of the water, for example, will typically produce very few mosquitoes.

Mosquitoes primarily breed in standing water, which may include ponds, bird baths, clogged rain gutters and containers that hold water for more than a few days. When in doubt, please report any areas of concern.

How do “Mosquito Dunks” Work?
Sold in tablets or donut-shaped discs, mosquito dunks contain a natural killer of mosquito larvae called BTi. Dunks prevent larvae from hatching, and each dunk effectively treats up to 100 square feet of surface water for one month, regardless of depth. Dunks are appropriate for use in larger areas of standing water that cannot be drained and are highly vegetated. BTi will not harm humans, pets or aquatic life.

Another product called Zodiac Preventative Mosquito Control comes in granular form and is also effective.

Where can I Obtain Mosquito Dunks for my Personal Use?
Mosquito dunks are available for purchase at most local home improvement stores and online. The city’s Public Works Department also has dunks available for free to residents on a first-come, first-served basis. Visit us at 1100 Bear Creek Parkway to pick one up.

Whom Should I Contact if I Suspect a Mosquito Breeding Ground in Keller?
To report suspected mosquito breeding sites in Keller, please call 817-743-4080 between 8 a.m. and 5 p.m. Monday through Friday, or email After 5 p.m., please call 817-743-4200.

Additional Suggested Resource: West Nile Virus Myths and Rumors