Current map of screwworm quarantine zones as of June 10, 2026.
The Texas Animal Health Commission has released an interactive map tracking cases of New World screwworm in Texas.
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Federal officials have confirmed five cases of the parasite in Texas as of June 10.
According to TAHC, three areas of the state have been designated as “infested zones” and include Gillespie, Kerr, Kimble, La Salle, Uvalde, Webb and Zavala counties. A quarantine is in place for those areas and warm-blooded animals cannot leave an affected area without authorization.
View the interactive map here: Interactive Map of NWS Zones
The U.S. Department of Agriculture is also tracking cases and has release a map showing where cases have been confirmed.
New World Screwworm in Texas
Timeline:
The U.S. Department of Agriculture confirmed June 9 that a calf in La Salle County tested positive for New World screwworm. Officials also confirmed a case involving a goat in Gillespie County on June 8.
The new detections come days after Texas officials announced the state’s first confirmed cases of the flesh-eating parasite in Zavala County.
According to the Texas Parks and Wildlife Department, the first case was identified June 3 in a three-week-old calf with an umbilical lesion. A second Zavala County case involving a 30-day-old calf with a similar lesion was confirmed June 5.
Officials initially reported an additional case involving a dog in Andrews County on June 8. However, after further epidemiological investigation, authorities determined the animal lives in Lea County, New Mexico, and the case was reclassified as New Mexico’s first confirmed New World screwworm infection.
The veterinarian who submitted samples from the dog is based in Texas, officials said. Early reports indicated the dog had recently traveled to Mexico.
State and federal officials said epidemiological investigations remain ongoing for recent detections.
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The Texas Parks and Wildlife Department said updates will be provided as additional cases are confirmed. The agency has established a public information page and said situation reports will be updated daily when new detections occur.
What is New World Screwworm?
The New World screwworm is considered one of the most devastating livestock and wildlife pests in history.
The insect gets its name because it’s only found in the Americas.
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It lays its eggs in the open wounds of animals, and its larvae become parasites. Unlike common fly larvae, screwworm maggots burrow into and feed exclusively on the living flesh of warm-blooded animals, causing severe injury, massive economic loss, and death if left untreated.
While rare, they can also infect humans.
Officials advised livestock owners and veterinarians to remain vigilant and report suspected infestations to the appropriate authorities. The Texas Animal Health Commission is handling livestock-related cases, while the Texas Department of State Health Services oversees human infestation reports.
The screwworm was mostly eradicated in Texas and the rest of the United States in the 60s. But now, it’s moving north up from Panama and has a known presence a little over 300 miles south of the Texas-Mexico border.
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To eradicate the population, federal officials are expediting the release of billions of laboratory-raised sterile flies, deploying ground release chambers to supplement the four million sterile flies already being dispersed aerially in the region each week. When wild flies mate with the sterile flies, no offspring are produced, eventually collapsing the population.
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