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Second Texas screwworm case confirmed as Abbott expands response

USDA says a second New World screwworm detection was confirmed in a Zavala County calf as Texas directs more resources to containment.

Camille Rourke

June 7, 20263 min read

Medical-style illustration showing how New World screwworm can infest animal wounds and how sterile fly releases help control the pest.
Medical-style illustration showing how New World screwworm can infest animal wounds and how sterile fly releases help control the pest.

Federal animal-health officials confirmed a second New World screwworm detection in Texas on Friday, June 5, after testing suspected cases. The U.S. Department of Agriculture's Animal and Plant Health Inspection Service said the case involved a one-month-old calf in Zavala County about 5.6 miles from the first confirmed detection.

For Frisco readers, the official state and federal releases reviewed for this story identify Zavala and Uvalde counties as the response priority and do not report a Frisco-area detection. The practical takeaway for North Texas livestock owners, pet owners, veterinarians and wildlife watchers is to monitor wounds, report suspect cases quickly and follow Texas Animal Health Commission guidance if animals have traveled or are moved.

What changed in the response

Gov. Greg Abbott's office said he issued a disaster declaration for Zavala and Uvalde counties and an updated statewide disaster declaration that authorizes the use of state resources and lets state personnel be reassigned as needed for the response. The Governor's office said resources will be prioritized to Uvalde and Zavala counties.

USDA said its APHIS strike team is already on site in Texas and that the National Veterinary Services Laboratories deployed an entomologist to the USDA Agricultural Research Service laboratory in Kerrville to speed confirmation work. USDA also said it has moved treatment supplies to Texas for affected producers in the infested zone.

Federal and state officials are using the sterile insect technique, a long-standing eradication method. USDA said aerial sterile fly releases began June 4 and will release 2 million sterile screwworms twice a week. The agency also said another 4 million sterile flies per week are being shipped to Texas for ground release through 24 chambers in and around the detection zone.

What officials are watching

USDA and TAHC said they are maintaining a 20-kilometer infested zone with quarantines, movement controls and heightened surveillance around the initial detection, while establishing a new 20-kilometer infested zone around the latest detection. The response also includes increased trapping along the border and outside the dispersal zone, wildlife surveillance and outreach to producers, veterinarians and communities.

New World screwworm is not a worm. It is a parasitic fly. CDC says infestations begin when a female fly lays eggs on a wound or body opening of a live warm-blooded animal. Larvae then feed on living tissue. The pest most often affects livestock, but official guidance says it can also infest pets, wildlife, birds and, rarely, people.

CDC's June 4 situation summary said no locally acquired human infestations had been reported in the United States. USDA also said the food supply remains safe because screwworms do not infest meat, fruits, vegetables or other food products, and affected animals would be identified through USDA Food Safety and Inspection Service inspection.

What to report

USDA urges people in the affected area to check animals for draining or enlarging wounds, maggots or egg masses, signs of discomfort and lesions in the nose, ears, genital area or umbilical area. Abbott's office said Texans should inspect livestock, pets and other animals daily, treat wounds promptly, reduce fly populations and not move an animal suspected of infestation.

DSHS says New World screwworm is not caught directly from an infested animal or person. The risk comes from adult flies laying eggs on wounds or mucous membranes. For people, CDC and DSHS list warning signs that include painful wounds that worsen or do not heal, a foul smell, bleeding, and seeing or feeling larvae in a wound or body opening.

Anyone who suspects an animal case should contact a veterinarian and TAHC at 1-800-550-8242. Wildlife concerns should be reported to Texas Parks and Wildlife or a local wildlife biologist. Anyone who suspects a human infestation should keep the wound covered and seek medical care promptly rather than trying to remove larvae on their own.

Sources

https://direct.aphis.usda.gov/news/agency-announcements/animal-health-officials-respond-second-detection-new-world-screwworm

https://direct.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/current-status

https://gov.texas.gov/news/post/governor-abbott-deploys-state-resources-to-combat-new-world-screwworm

https://gov.texas.gov/news/post/governor-abbott-issues-new-world-screwworm-disaster-proclamation-in-june-2026

https://www.cdc.gov/new-world-screwworm/situation-summary/index.html

https://www.cdc.gov/new-world-screwworm/hcp/clinical-overview/index.html

https://www.dshs.texas.gov/notifiable-conditions/zoonosis-control/zoonosis-control-diseases-and-conditions/new-world-screwworm

https://www.tahc.texas.gov/regs/pdf/2026-06-3-NWS-Zone01.pdf

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Camille Rourke

Camille Rourke covers community life, events, and neighborhood features around Frisco.

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