West Nile Virus



West Nile Virus (WNV) is a potentially serious virus transmitted by mosquitoes that, when contracted by humans, affects the central nervous system. While the large majority of people exposed to West Nile Virus never contract the disease, those who do can suffer very serious symptoms that in extreme cases can result in hospitalization or even death. The elderly, the very young, and persons with underlying health conditions affecting their immune system can be more susceptible. WNV is a blood-borne disease and is not spread through casual contact. More than 30 people in Lewisville came down with WNV in 2012.  Public health officials declared 2012 the worst season ever for WNV in North Texas.  There are simple precautions people can take to protect themselves and their families from the disease.

Residents also are encouraged to report standing water on city-maintained property by calling Code Enforcement at 972.219.3480.  Reports can also be made online.  For additional questions residents can call 972.219.3484.

How is West Nile Virus spread?
2015 west nile handout

West Nile Virus is spread by mosquitoes, and officials say the mosquito population often is enhanced by standing water and other conditions easily controlled by residents. The American Mosquito Control Association recommends the following steps to curb the mosquito population and reduce the chances of West Nile infection:
  • Destroy or dispose of tin cans, old tires, buckets, unused plastic swimming pools or other containers that collect and hold water.
  • Do not allow water to accumulate in the saucers of flowerpots, cemetery urns or in pet dishes for more than two days.
  • Clean debris from rain gutters and remove any standing water under or around structures or on flat roofs.
  • Repair leaks around faucets and air conditioner units.
  • Change water in birdbaths and wading pools at least once a week.
  • Stock ornamental pools with top feeding predacious minnows.
  • Fill or drain puddles, ditches and swampy areas, and either remove, drain or fill tree holes and stumps with mortar. These areas may also be treated with Bti or methoprene products.
  • Eliminate seepage from cisterns, cesspools and septic tanks.
  • Eliminate standing water around animal watering troughs. Flush livestock water troughs twice a week.
  • Check for trapped water in plastic or canvas tarps used to cover boats, pools, etc. Arrange the tarp to drain the water.
  • Check around construction sites or do-it-yourself improvements to ensure that proper back filling and grading prevent drainage problems.
  • Irrigate lawns and gardens carefully to prevent water from standing for several days.
  • If ditches do not flow and contain stagnant water for one week or longer, they can produce large numbers of mosquitoes.
What is the city doing?
Lewisville officials have developed a program of public education, mosquito monitoring, and disease response intended to reduce the impact of WNV on local residents and reduce the chance of widespread infection.

The city will be actively trapping mosquitoes on April 27, 2018 and submitting these samples to determine the presence of WNV. City crews are regularly walking through and visually inspecting creeks and drainage channels to look for potential mosquito breeding sites. The city has nearly a dozen parks and animal services workers who are state-certified to apply anti-larval dunks or localized pesticide to curb the mosquito population. Residents are encouraged to report any mosquito complaints to Chris McGinn at 972.219.3484.

The city is also working with local retailers to display WNV information signs, including self-protection tips, and will display similar signs at municipal facilities. The public education campaign also includes digital billboards, posters, flyers, video announcements and online information.

Citizens may purchase "Mosquito Dunks" inexpensively at local retailers that provide insecticides or repellents to assist with personal protection in combating the insects. These dunks are safe when used as instructed, and can kill mosquito eggs and larva in standing water sources such as ponds, birdbaths and rain gutters -- all of which can be active breeding sources for disease-carrying mosquitoes. The dunks are also safe to use around fish and pets.

Protecting yourself
WNV 4 D's flyer Self-Protection is still a must when it relates to protecting yourself and love ones against mosquito bites and for the potential diseases that they could be carrying. Please continue following the State's four D's instruction guidelines for added protection. 

Health officials reported in 2012 that more than 70 percent of people in North Texas who contracted WNV admitted to not having taken basic precautions, including the use of bug spray. The best protection is self protection! Residents are urged to implement some simple steps to protect themselves from WNV exposure and infection.

The Texas Department of Health recommends four steps (The 4 D's):
  • Try to stay indoors at dusk and dawn, when mosquitoes tend to be most active.
  • Dress in long sleeves and pants when outdoors (weather permitting), especially at dusk and dawn.
  • Use repellent containing the active ingredient Defend (Deet) when going into areas where mosquitoes might be active; organic options are available on the Internet and have been cited by some people as being effective, although not specifically recommended by public health officials.
  • Drain standing water from such sources as tires, flowerpots, clogged rain gutters, cans, buckets and ground depressions. These are prime mosquito breeding areas.

Additional resources
The Texas Department of Health operates a toll-free WNV information line in both English and Spanish at 888.883.9997, and has expanded information posted on its Web site at tdh.state.tx.us. Denton County Health Department also has information about West Nile virus at 940.349.2907, or on the Web at DentonCounty.com/wnv.  Texas A&M AgriLife Extension also has information.

Centers for Disease Control has posted a short but very informative document called "Five Common Myths about West Nile Virus.