Denton County Reports First Neuroinvasive West Nile Case as Virus Spreads Across North Texas

Denton County Public Health confirmed Thursday the county's first neuroinvasive case of West Nile virus this year, a severe form of the mosquito-borne illness that attacks the central nervous system. The patient, a resident of The Colony, represents the second human case in Denton County this season.

The announcement comes three weeks after county officials reported a Denton resident had contracted the milder, non-neuroinvasive form of the disease on July 10. The gap between cases illustrates the persistent threat posed by Culex mosquitoes across North Texas, even as summer temperatures peak.

Understanding the Risk

Neuroinvasive West Nile virus is the most dangerous manifestation of the disease. According to the Centers for Disease Control and Prevention, less than 1% of infected individuals develop this severe form, which can cause inflammation of the brain or spinal cord. Approximately 10% of those who develop severe illness die.

"There are currently no vaccines or medicines to prevent West Nile Virus in people," said Juan Rodriguez, DCPH assistant director and chief epidemiologist, in a press release. "We encourage all community members to practice prevention to reduce their risk."

The virus spreads through the bite of an infected mosquito that has fed on infected birds. About one in five people infected will develop symptoms, which typically include headache, fever, gastrointestinal upset, body aches, and occasionally a rash. Symptoms usually appear two to 10 days after a mosquito bite.

For those who develop severe disease, long-term complications can emerge months or even years later, including fatigue, muscle weakness, memory loss, and depression—symptoms that infectious disease specialists say can resemble chronic fatigue syndrome or long COVID.

Prevention Measures

Denton County officials recommend residents take several precautions to reduce exposure:

Avoid outdoor activity during dusk and dawn, when mosquitoes are most active. Wear long sleeves and pants when outside during these hours. Apply insect repellent containing DEET, picaridin, or oil of lemon eucalyptus. Eliminate standing water on your property, and use Bti briquettes—commonly called mosquito dunks—in standing water that cannot be drained.

The county maintains an interactive map showing locations where mosquitoes have tested positive for West Nile virus, allowing residents to assess risk in their specific areas.

Broader Context

The Denton County case adds to a growing tally of West Nile infections across Texas this season. Tarrant County confirmed its first human case—a neuroinvasive infection in a Fort Worth area resident—on July 24. Brazoria County reported positive mosquito samples in Pearland, Lake Jackson, and West Columbia earlier this week.

The pattern reflects what health officials warned would be an active season. CDC data current through July 28 shows West Nile virus circulating in multiple states, with Texas among those reporting human cases.

As August approaches—the historically peak month for West Nile transmission in Texas—health departments across the state are intensifying surveillance and, in some areas, conducting ground spraying operations to reduce mosquito populations.

For Denton County residents, the message is clear: the virus is present, the risk is real, and personal protection remains the primary defense against infection.