Expanded Mosquito Trapping Tests Positive for West Nile Virus

Two mosquito trap samples collected in Georgetown have tested positive for West Nile virus. This is the second West Nile virus positive for the trap located on Yellow Rose Trail in the past two weeks. The Williamson County and Cities Health District (WCCHD) set up an expanded trap sites in addition to the original site from Aug. 11 and one of the expanded traps also had a positive test result yesterday. No other samples were found to be positive from routine trapping this week as part of the WCCHD Integrated Vector Management program. 

West Nile Virus is the most common mosquito-borne disease in the United States. In 2020, there have been seven mosquito trap pools that returned positive for West Nile Virus in Williamson County. 

The City is following the Health District’s Best Practices for Integrated Mosquito Management which, at this time, calls for truck-mounted spraying, along with enhanced monitoring and testing and increased public outreach and education. Enhanced mosquito control efforts will also continue with the treatment of standing water with larvicide.  

The city is implementing insecticide spraying in the vicinity of the positive sample for three consecutive nights. Starting August 21, a City vehicle will use a pyrethrin-based insecticide along the street right-of-way and in public parks, weather permitting. Pyrethrin is a chemical that can be found in chrysanthemums. 

A map is included showing the area where the application of the insecticide is planned. The use of the insecticide will reduce the adult mosquito population in that area. Spraying will be done if the wind speed is less than 10 mph. 

Although the mosquito control product poses no significant health risk, if possible, people and pets may want to stay indoors during spraying.  

The City and the Health District are encouraging everyone to be especially vigilant about protecting themselves from mosquito bites when outdoors, and preventing mosquito breeding on their personal property. Recent rain and continued warm temperatures are prime breeding conditions for mosquitoes. 

 While there have been no incidences of human infection of West Nile Virus in Williamson County this year, symptoms of infection may include fever, headache, and body aches, a skin rash on the trunk of the body, and swollen lymph nodes. Those age 50 and older and/or with compromised immune systems are at higher risk for severe symptoms, which may include stiffness, disorientation, coma, tremors, vision loss, paralysis, and in rare cases, death.  

Mosquitoes are present in Central Texas year-round, but the population is largest and most active from May through November. During this period, WCCHD monitors the mosquito population and tests for mosquito-borne viruses.  

The most important way to prevent West Nile Virus is to reduce the number of mosquitoes where people work and play. Health officials strongly encourage everyone to remain vigilant about protecting themselves from mosquito bites and preventing mosquito breeding on their personal property. Mosquitoes breed in standing water, needing as little as one teaspoon. By draining all sources of standing water in and around your property, you reduce the number of places mosquitoes can lay their eggs and breed. 

What you can do 
Eliminating places where mosquitoes can breed and reducing the chances of mosquito bites are the most effective lines of defense against exposure to West Nile Virus. As part of its Fight the Bite campaign the Health District recommends the 3 Ds of mosquito safety: 

  • Drain standing water in flowerpots, pet dishes, or clogged gutters so mosquitoes don’t have a place to breed and treat water that can’t be drained,
  • Defend by using an EPA-approved insect repellent, and
  • Dress in long sleeves and pants when outdoors. 

For more information, go to the WCCHD website at www.wcchd.org or visit the Texas Department of State Health Services West Nile website at txwestnile.org. 

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