Today marks the start of West Nile season in Fort Worth and Grand Prairie, following Tarrant County Public Health’s announcement of mosquitoes testing positive during routine surveillance.
No human cases of the virus have been reported. In 2025, residents of Dallas, Tarrant, Collin, Denton and Rockwall counties developed West Nile fever, according to data from the Texas Department of State Health Services.
West Nile is the leading mosquito-borne disease in the U.S. and is transmitted to people through bites, according to the CDC.
The virus is most common in North Texas from May to October, as warmer temperatures bring increased mosquito activity, the health release said. Tarrant County Public Health regularly collects and tests mosquitoes for the virus.
Most infected people do not show symptoms, but about 1 in 5 develop headaches, fevers, body aches or joint pain, the release said. The virus can also lead to more serious, but rare, complications affecting the nervous system and brain.
There are no preventive vaccines or treatments available for people who contract West Nile.
Tarrant County Public Health provided the following ways to prevent possible infection and mosquito breeding areas near homes: