Dallas County Health and Human Services confirmed West Nile virus in mosquito pools across three locations this week, marking the first positive tests in the county for 2025.
Mosquito samples collected in Irving’s 75061 ZIP code, Richardson’s 75080 ZIP code, and Rowlett’s 75088 ZIP code tested positive for the virus, which is primarily spread by infected mosquitoes. However, other bloodsucking arthropods, such as fleas and ticks, can also transmit the virus.
The findings follow Tarrant County Public Health’s report of a positive mosquito sample on May 8, signaling the start of the West Nile virus season in North Texas, which typically spans May through October.
Summer heat fuels mosquito activity, increasing the risk of virus transmission. Most cases occur during mosquito season, which starts in the summer and continues through the fall.
While most infected individuals show no symptoms, about 1 in 5 may develop fever, headache, body aches, or joint pain. In rare cases, about 1 in 150 infected persons may develop a serious, or even fatal, illness affecting the brain or nervous system.
The virus can rarely be transmitted through blood transfusions, organ transplants, breastfeeding, or from mother to baby during pregnancy, but not through person-to-person contact like touch or saliva.
To curb the spread, Dallas Health and Human Services recommends using DEET or EPA-approved repellents daily, wearing long, loose, light-colored clothing outdoors, draining standing water around homes, and limiting outdoor activity at dusk and dawn when mosquitoes are most active. The cities of Irving, Richardson, and Rowlett have begun spraying high-risk areas to prevent further spread.
No human cases have been reported in Dallas County this year, and officials urge residents to remain vigilant as the season progresses.