Dallas County

Ahead of West Nile Virus' Seasonal Return, Dallas County Health Issues Warning

No human cases, positive traps yet reported in Dallas County

NBC 5 News

Dallas County Health and Human Services Department is sending out their annual reminder for North Texans to take precautions against the potentially deadly West Nile virus.

West Nile virus is a mosquito-borne disease spread to people by a bite from an infected mosquito.

About 20% of infected people will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of disease recover completely, but fatigue and weakness can last for weeks or months. People age 50 and older run a higher risk of developing a severe infection.

The virus was first reported in the U.S. in 1999 and it was first known to have arrived in Dallas County in 2002. Dallas County reported its most severe years of the virus in 2012, when aerial spraying was done to kill mosquitoes and combat the spread of the virus, and then in 2016 and 2020.

In 2020, Dallas County reported a significant increase in WNV disease prevalence with 20 human cases, five fatalities and 498 positive mosquito tests. In the previous high years, there were 274 positive tests and 398 human cases in 2012; 705 positive tests, and 61 human cases in 2016.

"Even though we still need to be concentrating on how to live safely with COVID-19, we cannot forget about West Nile virus. As the summer heats up and more people are getting outside, remember the four D's: Dress, Drain, Dusk/Dawn, and DEET," said Dr. Philip Huang, Director of DCHHS.

So far there have been no confirmed human cases of West Nile virus in Dallas County in 2021 or positive traps. The Tarrant County Public Health Department confirmed their first West Nile virus sample on Wednesday afternoon.


  • Dress in long sleeves, pants when outside: For extra protection, spray thin clothing with repellent.
  • DEET: Make sure this ingredient is in your insect repellent.
  • Drain standing water in your yard and neighborhood: Mosquitoes can develop in any water stagnant for more than three days.

It has been recommended in the past that to avoid mosquito bites you should avoid being outdoors during Dusk and Dawn (the 4 Ds). While this is true for mosquitoes that commonly carry the West Nile virus, other types of mosquitoes that are more likely to carry Zika, dengue and chikungunya are active during the day. When outdoors, no matter what time of day, adjust your dress accordingly and wear insect repellent containing DEET, picaridin or oil of lemon eucalyptus as your first line of defense against insect bites

More on Dallas County's WNV prevention and tracking page can be found here.

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