The New World Screwworm outbreak in Texas presents a genuinely mixed picture as of late June 2026: new cases continue to be confirmed, even as some previously identified infestations have been successfully resolved.
The Texas Animal Health Commission has confirmed New World Screwworm (NWS) cases have reached 25 in the state, with the most recent additions occurring in sheep in Crockett and Edwards counties and cattle in Medina County — areas where quarantine measures remain firmly in effect. At the same time, three cases in the broader regional outbreak, including the single previously confirmed New Mexico detection, are now listed as inactive, indicating those specific infestations have been successfully treated and resolved.
Why This Matters
New World Screwworm re-establishing itself in the United States after its eradication in the 1960s would represent a significant threat to livestock industries and animal health. Understanding the current trajectory — whether cases are accelerating, plateauing, or beginning to resolve through treatment — is essential for ranchers, pet owners, and public health officials assessing the appropriate level of concern and resource allocation.
The mixed picture reflects the genuine difficulty of fully eradicating NWS once it has re-established even a small foothold near the U.S.-Mexico border: new cases continue to emerge in proximity to existing quarantine zones even as individual animal infestations are successfully treated.
What We Know So Far
All 25 confirmed Texas cases have been in livestock — sheep and cattle — concentrated in Medina, Crockett, and Edwards counties in southwest Texas. The most recent additions, as previously reported, included five new cases in sheep across Crockett and Edwards counties and one new case in cattle in Medina County.
Quarantine measures established by the Texas Animal Health Commission remain in effect in the affected counties, restricting the movement of livestock to prevent the parasite's further spread.
Separately, the single previously confirmed case in New Mexico — along with two other cases in the broader regional outbreak — is now listed as inactive. An "inactive" classification indicates that the specific infestation has been successfully treated and that the animal is no longer carrying active NWS larvae, representing a successful individual treatment outcome even as the broader outbreak continues.
What "Active" Versus "Inactive" Means for This Outbreak
Understanding the distinction between active and inactive case status is important for accurately interpreting the outbreak's trajectory:
Active cases represent animals currently infested with NWS larvae, requiring ongoing treatment and triggering quarantine measures in the surrounding area to prevent further spread.
Inactive cases represent animals where the infestation has been successfully treated and resolved — the wound has been cleaned, larvae removed, and the animal has recovered without re-infestation. This classification does not mean the broader outbreak has ended; it means that specific case has been resolved.
The combination of new active cases continuing to emerge alongside successful resolution of prior cases describes a situation under active management rather than one that is either rapidly worsening or fully contained.
Where the Risk Remains Highest
Quarantine zones remain in effect in Medina, Crockett, and Edwards counties in Texas. USDA APHIS continues to conduct sterile insect technique (SIT) releases in the affected region — the same eradication method responsible for the parasite's elimination from the U.S. in the 1960s — to reduce the wild fly population's ability to reproduce.
Pet owners in and near these counties should continue daily wound checks on dogs and cats, as the parasite can infest any warm-blooded animal with an open wound, not only livestock.
What Doctors and Veterinary Experts Say
Veterinary authorities continue to emphasize that successful resolution of individual cases — as seen with the New Mexico detection and two other now-inactive cases — demonstrates that prompt identification and treatment remain effective at stopping individual infestations from spreading further. The continued emergence of new cases in Texas, however, indicates that the underlying wild fly population near the border has not yet been fully suppressed.
The historical eradication of NWS from the United States, completed by the mid-1960s, remains one of the most successful agricultural pest eradication programs in history — providing genuine grounds for confidence in long-term containment even as the current situation requires sustained vigilance in the near term.
Who Faces the Greatest Risk?
- Livestock in and near the quarantine-affected counties of Medina, Crockett, and Edwards
- Pets (dogs and cats) with open wounds in or near affected areas
- Wildlife in the affected region
- Rarely, humans with untreated open wounds in affected areas
What You Can Do Now
- If you own livestock in or near Medina, Crockett, or Edwards counties, continue daily wound inspections and report any suspected NWS detection immediately to USDA APHIS at 1-888-702-7020.
- If you own pets in the affected region, inspect dogs and cats daily for wounds, unusual skin irritation, or behavioral changes, and treat any wounds promptly.
- Ask your veterinarian about the FDA emergency-use-authorized generic nitenpyram as a precautionary treatment option for dogs and cats in affected areas.
- Monitor the Texas Animal Health Commission and USDA APHIS websites for updated quarantine zone boundaries and case status.
What Happens Next
USDA APHIS sterile insect releases continue in the affected region. The Texas Animal Health Commission will continue to update case status as new detections occur and as existing cases are resolved. MedicalDaily will report on any significant expansion of the quarantine zone or changes in the active-to-inactive case ratio that would indicate a meaningful shift in the outbreak's trajectory.
The Bottom Line
Texas New World Screwworm cases have reached 25, with new detections continuing in three southwest Texas counties under active quarantine. At the same time, three cases — including the New Mexico detection — have been successfully resolved and are now classified as inactive. This mixed but informative picture reflects both the ongoing challenge of containing NWS near the border and the continued effectiveness of prompt treatment once individual cases are identified.
