Mosquito Diseases in Texas: West Nile, Zika & Dengue Risk

A mosquito-borne disease is an illness caused by a pathogen — a virus or parasite — that is transmitted to humans through the bite of an infected mosquito, with West Nile virus being the only such disease with consistent annual human transmission across Texas.

Texas mosquitoes vector multiple human pathogens, but the actual risk to any individual Texan varies enormously by disease, region, and season. Understanding which diseases are genuinely active in your area helps you calibrate your mosquito management decisions appropriately.

Why Is West Nile Virus the Primary Endemic Threat in Texas?

West Nile virus is the only mosquito-borne disease with consistent annual human transmission throughout Texas. It's transmitted by Culex quinquefasciatus and is endemic in every Texas county. Risk peaks July–September in North and Central Texas. Most infected individuals have no symptoms; severe neurological disease affects less than 1% but is serious, disproportionately affecting adults over 60.

Where Does Dengue Have Local Transmission in South Texas?

Dengue fever sees periodic local transmission in South Texas border communities — particularly in Hidalgo, Cameron, and Webb counties where Aedes aegypti populations are high and travel-related introductions occur frequently. Most dengue infections cause fever, severe headache, joint pain, and rash. Avoid mosquito bites in South Texas during summer, particularly if traveling to and from Mexico.

What Is the Current Status of Zika and Chikungunya in Texas?

Active domestic Zika transmission in Texas occurred primarily in 2016–2017 in Brownsville. Current domestic transmission risk is low, but the Aedes aegypti population that supported transmission remains present in South Texas. Chikungunya, causing severe joint pain that can persist for months, is not currently endemic in Texas but sees travel-related introductions from Caribbean and Latin American endemic areas.

Where Does Eastern Equine Encephalitis Risk Exist in East Texas?

EEE is a rare but extremely severe mosquito-borne encephalitis with a 30% fatality rate. In Texas, it's transmitted in the Piney Woods and Big Thicket wetland areas of East Texas. Human cases are rare but occur periodically. Outdoor workers and recreationists in Tyler, Lufkin, Nacogdoches, and surrounding areas during late summer should be aware of EEE risk.

How Should Texans Calibrate Mosquito-Disease Risk by Region?

Practical risk is not uniform across Texas, so generic "protect yourself from mosquitoes" advice under-serves residents. In the Dallas–Fort Worth and Houston metros, West Nile virus is the dominant concern and risk peaks July through September, which is when property-level adult-mosquito reduction has the most value. Along the Rio Grande Valley border counties — Hidalgo, Cameron, and Webb — Aedes aegypti is established and periodic local dengue transmission occurs, so container source-reduction matters year-round. In the East Texas Piney Woods, the rare but severe Eastern equine encephalitis circulates in wetland areas. Matching the control method to the regional vector is the core of effective mosquito fogging and control; residents in the highest-pressure metro can schedule an assessment through our Houston mosquito control service.

Which Mosquito Species Carries Which Disease in Texas?

Distinguishing the two main vector groups explains why control timing differs. Culex quinquefasciatus — the southern house mosquito — is the West Nile workhorse: it breeds in stagnant, organically rich water such as clogged gutters, neglected ponds, and storm-drain catch basins, and it feeds at dusk and dawn, which is why evening yard activity drives most North Texas exposure. Aedes aegypti and Aedes albopictus — the container mosquitoes behind dengue, Zika, and chikungunya — breed in small clean-water containers and bite aggressively during the day, so daytime outdoor work in South Texas is the higher-risk window there. Eastern equine encephalitis involves freshwater-swamp Culiseta and Aedes species in the East Texas wetlands. Because the species behave so differently, a single calendar-based spray schedule is rarely optimal; an inspection that identifies the dominant on-site vector lets a professional mosquito program target the correct breeding habitat. Households in the Rio Grande Valley facing Aedes pressure can reach a local crew through Brownsville pest control, and Central Texas residents through Austin mosquito control.

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