West Nile Virus

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West Nile virus has become a serious concern in our community.  This is in large part due to the record outbreak of West Nile virus in North Texas during the summer of 2012.  Over 580 confirmed human cases resulted in 23 deaths in Collin, Dallas, Denton and Tarrant counties last year.  The U.S. Centers for Disease Control and Prevention evaluated this outbreak and provided feedback to improve state and local response.  This guidance has been incorporated into Carrollton's program.  Our success depends heavily on a strong partnership with our community.

You may review our latest updates by calling our West Nile Virus Hotline at (972) 466-3202 or by clicking here

You may also review a map of our fixed testing sites by clicking here.

What is West Nile virus?  photo of mosquito 

West Nile virus is a virus commonly found in Africa, West Asia and the Middle East.  It is not known how long it has been in the United States, but the Centers for Disease Control and Prevention (CDC) believe the virus probably has been in the eastern United States since early summer 1999.  It is closely related to the St. Louis encephalitis virus found in the United States.  The virus can infect humans, birds, mosquitoes, horses and some other animals. 

How can I reduce my risk of getting West Nile virus?

Mosquito Spray - protect against West Nile Virus

Preventing mosquito bites is the best way to avoid becoming infected with the West Nile virus.  Remember the "Four D's" of Defend, Dress, Dusk to Dawn, and Drain:  

  • Defend yourself by applying an approved mosquito repellent. 
    • Spray exposed skin and clothing with repellent. 
    • Click here for information on choosing an appropriate repellent. 
  • Dress in long sleeves and long pants when you are outside. 
  • Stay indoors from the period of dusk through dawn, times when infected mosquitoes are most active.
  • Drain standing water in your yard; old tires, flower pots and clogged rain gutters are mosquito breeding sites.
  • Also very important to be sure that doors and window are sealed properly and that screens are in place to protect your home from intruding mosquitoes. 

What are the symptoms of West Nile virus?  

Most people infected with West Nile virus will not have any signs of illness.  Twenty percent of people who become infected will have only mild symptoms such as fever, headache, body aches and occasionally a skin rash on the trunk of the body.

The symptoms of severe infection (West Nile neuroinvasive disease) include headache, high fever, neck stiffness, disorientation, muscle weakness and paralysis.  Only about 1 out of 150 people infected with West Nile virus will develop this more severe form of the disease.  

The incubation period of West Nile virus in humans is 3-14 days.  Symptoms of mild disease may last a few days.  Symptoms of severe disease may last several weeks, although neurological effects may be permanent.  Rarely, death can occur.

How is it spread?

West Nile virus is spread by the bite of an infected mosquito and can infect people, horses, many types of birds and some other animals.  There is no evidence that West Nile virus can be spread from person to person or from animal to person.

Who is at risk for West Nile virus?

People older than 50 have the highest risk of severe disease and people with with weakened immune systems are at an increased risk for West Nile virus.

How likely am I to be bitten by an infected mosquito?

Less than 1 percent of those bitten by infected mosquitoes become severely ill. If you have the symptoms mentioned above, contact your doctor immediately.

Please take a moment to review this interactive video to learn more about mosquitoes and how you can reduce mosquito breeding sites on your property.


Carrollton's P.E.S.T.S. Programfight the bite

Partnership - Carrollton wants to play a key role in our partnership with local residents business owners by being receptive and responsive to reported concerns related to West Nile virus.  To make a report please call (972) 466-3420.  You may email your report by clicking here.

Education - The key to lowering the risk associated with most public health concerns is public education.  One of our primary missions is ensuring that we provide our community with up-to-date information on how to protect yourself from exposure to mosquito bites.  Each mosquito season (May-September) you will notice a number of signs in our medians, major intersections and parks reminding folks of the "Four D's", Defent, Dress, Dusk through Dawn, and Drain.  By following these simple steps you can significantly reduce your risk.

gravid trap

Surveillence - Carrollton has established four fixed testing sites to monitor both mosquito counts and West Nile Virus activity within our local mosquito population.  Each week these traps are set and the collected mosquitoes are tested for West Nile virus.  

Treat standing water - Our teams in Animal Services and Community Services work together to identify areas of standing water that may become breeding sites for mosquitoes.  These sites include low spots on undeveloped property, blocked creeks and drainage easements and abandoned swimming pools.  These areas are treated with a larvacide that will prevent larval mosquitoes from transitioning to the adult stage where they can transmit the West Nile virus.   We use mosquito dunks for this application, a product available to the general public that may be purchased at your local hardware store.

It is important to note that we do not treat water standing on streets and sidewalks.  This water is often disturbed by pedestrian and/or vehicular traffic and does not contain the organic material needed to make it a viable breeding site for mosquitoes.

Spraying - ground spraying of a permethrin-based product is reserved for areas where we have collected mosquitoes that have tested positive for West Nile virus.  We do not spray areas based on complaints as over-exposing mosquitoes to our selected pesticide may result in our local mosquito population developing a resistance making our spraying less effective. 

spray rig

Para Información en Espanol:




Additional Resources:

The Centers for Disease Control and Prevention (CDC):


Texas Department of State Health Services:



Dallas County Health and Human Services Website:




To send additional questions or comments please click here. If you would like to speak with a member of our staff please call 972-466-3420.


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