The 2026 North Texas Mosquito Report

West Nile virus is the most common mosquito-borne illness in the continental United States, and North Texas has one of the longest and most-studied histories with it of any U.S. metro. This report compiles publicly reported figures for the four core Dallas–Fort Worth counties from the agencies that track the disease — the Texas Department of State Health Services (DSHS), the U.S. Centers for Disease Control and Prevention (CDC), and county health departments. Every figure below is sourced; the full citation list is at the end of the page.

The 2012 benchmark: the worst outbreak in U.S. history

To understand North Texas and West Nile, you have to start with 2012. That year, Texas recorded 1,868 human cases and 89 deaths statewide — the largest West Nile outbreak the country had ever seen. The Dallas–Fort Worth metro was the epicenter, accounting for 902 cases, roughly 48% of the entire state total.

Here is how those 902 metro cases broke down across the four core counties:

Dallas County bore the heaviest toll: 19 deaths and a record neuroinvasive disease incidence of 7.3 cases per 100,000 residents— the figure that drove the county to declare a public-health emergency and conduct aerial spraying that summer.

The 2025 season: a county-by-county comparison

The table below compares the four core counties across the three measures that matter most for West Nile risk: confirmed human cases, the number of mosquito samples (“pools”) that tested positive for the virus, and the per-capita case rate that normalizes for each county’s population.

Statewide in 2025, Texas reported 1,284 positive mosquito pools, 125 human cases, and 4 deaths.

Data note: the 2025 county figures are preliminary, drawn from the Texas DSHS Arbovirus Activity Report (Week 50, December 13, 2025). They will be updated when DSHS publishes its finalized annual summary.

The finding: the center of gravity has shifted west

In 2012, Dallas County was the unambiguous epicenter — 396 cases, 19 deaths, and a record per-capita rate. In 2025, that is no longer where the pressure concentrates. Tarrant County led all four core counties in 2025 on every measure:the most human cases (17), the most positive mosquito pools (289), and the highest per-capita rate (~0.79 per 100,000) — more than double Dallas County’s ~0.30.

This is the report’s central, citable finding: the most intense West Nile activity in the metro’s most recent season was centered not in Dallas but to its west, in Tarrant County and communities such as Fort Worth and Arlington. It is worth stating plainly what this does and does not mean: a single season is not a trend, and case counts are sensitive to testing, weather, and reporting. But on the 2025 numbers, the county that carries the metro’s heaviest historical association with West Nile — Dallas — was not the county with the heaviest current burden.

Where the 2026 season stands now

The 2026 West Nile season opened in mid-May, with Tarrant County reporting the metro’s first activity of the year around May 15.

As of late June 2026, the West Nile season is underway in North Texas. Positive mosquito samples have been confirmed in Tarrant County (Fort Worth and Grand Prairie) and Dallas County, among eight Texas counties reporting positive pools so far. No human cases have yet been reported in the four core DFW counties this season. Texas’s first confirmed 2026 human case was reported in Harris County in May. This section will be updated with county case and positive-pool counts as DSHS and county health departments report them through the season.

We do not estimate in-season figures.

Why North Texas is a West Nile hotspot

North Texas combines several conditions that favor the Culex mosquitoes that carry West Nile:

• Blackland Prairie clay soils. The region’s heavy, slow-draining clay holds water at the surface after rain and irrigation, creating the shallow, stagnant pools where Culex larvae develop.
• Engineered stormwater retention ponds.The metro’s master-planned suburbs are dotted with retention and detention ponds that hold standing water through the warm months.
• Creek and lake watersheds. Extensive creek systems and reservoirs across the four counties provide year-round breeding margins and backwater habitat.
• Mild winters and long, hot summers. Relatively mild winters allow Culexmosquitoes to overwinter, and the region’s long, hot summers extend the transmission season well into the fall.

For a season-specific look at how these conditions play out across the metro, see our DFW mosquito season guide and the mosquito control overview.

How to reduce your risk

Public-health guidance from the CDC and local health departments focuses on eliminating breeding sites and reducing exposure. The practical steps for households:

• Drain standing water weekly. Empty and scrub anything that holds water — flowerpot saucers, buckets, toys, tarps, clogged gutters, birdbaths, and pet bowls. Culex can complete their life cycle in as little as a tablespoon of water.
• Treat water that cannot be drained. For ornamental ponds and rain barrels, mosquito-control products containing Bacillus thuringiensis israelensis (Bti) target larvae and are harmless to fish, pets, and wildlife.
• Use EPA-registered repellent. Products with DEET, picaridin, IR3535, or oil of lemon eucalyptus are effective when used as directed.
• Dress and time it. Wear long sleeves and pants and limit outdoor exposure at dawn and dusk, when Culex mosquitoes are most active.
• Keep them out. Repair torn window and door screens and make sure they seal.

Mosquito control by North Texas city

• Mosquito Control in Dallas→
• Mosquito Control in Fort Worth→
• Mosquito Control in Arlington→
• Mosquito Control in Plano→
• Mosquito Control in Frisco→
• Mosquito Control in McKinney→
• Mosquito Control in Garland→
• Mosquito Control in Irving→

Sources

This report compiles figures reported by public-health agencies and credited news coverage. Where a stable primary source is available, it is linked directly.

• Texas Department of State Health Services (DSHS) — Arbovirus Activity Report, Week 50 (December 13, 2025). Source of the 2025 county and statewide figures. DSHS Week 50 report (PDF) · DSHS West Nile hub
• Texas DSHS — first confirmed 2026 Texas West Nile case (Harris County, May 2026). Source for the 2026 season status. dshs.texas.gov news alert
• CDC / NIH — “Epidemic West Nile Encephalitis, Texas, 2012” (PMC3837649). Source of the 2012 benchmark figures. ncbi.nlm.nih.gov/pmc/articles/PMC3837649
• NPR — “A Warm Winter Helped Fuel West Nile Outbreak In Dallas” (2013), on the 2012 outbreak. npr.org
• KERA News — reporting on the opening of the 2026 North Texas mosquito season in Tarrant County. keranews.org
• U.S. Centers for Disease Control and Prevention (CDC) — West Nile virus national surveillance and prevention guidance. cdc.gov/west-nile-virus
• U.S. Census Bureau — 2025 population estimates, used as the per-capita denominators. census.gov
• County health departments— Dallas County Health and Human Services, Tarrant County Public Health, Denton County Public Health, and Collin County Health Care Services, which conduct local mosquito trapping and report county case data to DSHS.

Pestcura is a nationwide network connecting homeowners to licensed local pest control professionals; we do not perform pest control services. This report is an editorial data compilation for public information and is not medical advice. For health concerns related to West Nile virus, consult a physician or your local health department.