San Antonio is taking proactive measures to combat mosquito-borne diseases after the early detection of West Nile virus in a mosquito trap near Hillcrest Drive and Bandera Road in Northwest San Antonio. With warmer temperatures, humidity, and recent rainfall creating ideal conditions for mosquito development, city and county officials are urging residents to take precautions.
The San Antonio Metropolitan Health District, along with Bexar County’s Department of Public Works, is ramping up efforts to monitor and control the mosquito population. This includes setting traps, testing for diseases, and treating standing water with insecticides. Despite the early detection, there have been no reported human cases of West Nile virus in Bexar County this year.
Understanding mosquitoes and West Nile virus
Among the over 80 species of mosquitoes in Texas, only a few are known to carry diseases like West Nile virus. These mosquitoes typically contract the virus by feeding on infected birds and then transmit it to humans through bites. Nuisance mosquitoeswhich are more common, are not significant carriers of diseases but can still be a nuisance with their painful bites.
Most people infected with West Nile virus do not experience any symptoms. However, about 1 in 5 people may develop flu-like symptoms. In rare cases, the virus can affect the central nervous system, leading to severe complications. From 2026 through 2026, Texas has reported 881 cases of West Nile neuroinvasive disease.
Local efforts to control mosquito populations
The San Antonio Metropolitan Health District and Bexar County’s Department of Public Works have implemented comprehensive mosquito control programs. These programs involve placing mosquito traps in 20 locations around the city, which are checked and tested weekly for the presence of West Nile virus. If a mosquito pool tests positive, the city deploys insecticide from trucks, a process known as foggingand treats specific pools of standing water.
Positive hits for West Nile virus typically occur in mid to late summer in San Antonio. This year’s early detection may be due to the higher amounts of rainfall experienced this spring. Factors such as bird migration can also influence mosquito populations and the spread of diseases.
Protecting yourself from mosquitoes
The most effective way to keep mosquitoes away is to eliminate stagnant water around your home, as mosquitoes reproduce in standing water. Even small amounts of water, such as an overturned bottle cap, can breed mosquitoes. Regularly check and clean rain gutters, animal food bowls, bird baths, and other potential breeding grounds.
For water that cannot be eliminated, consider treating it with insecticide. However, avoid relying on broad insecticides in the long term, as they can harm natural predators of mosquitoes like dragonflies. Instead, use Bti productswhich target mosquito larvae without harming most other insects.
When spending time outdoors, especially during dawn and dusk when mosquitoes are most active, wear long sleeves and pants, or apply insect repellent. Joel Larasenior environmental health officer at Metro Health, emphasizes the importance of these precautions: “Water is the big thing. Stay indoors during dawn and dusk, wear insect repellent, and cover yourself up when you know you might encounter mosquitoes.”