USDA Confirms New World Screwworm Detections in Texas and New Mexico in June 2026

June 10, 2026

In a press release dated June 3, 2026, the USDA Animal and Plant Health Inspection Service confirmed detection of New World screwworm (NWS) in a 3-week-old calf located in Zavala County, Texas. This was the first confirmation since NWS was eradicated from the US in the 1960s, aside from a localized outbreak in Key deer in Florida in 2016-2017. Additional NWS detections have increased to six total domestic animal cases as of June 9, 2026, including four cattle, one goat and one dog case. The single case in a pet dog was identified in Lea County, New Mexico, on June 8, 2026, highlighting potential routes for further spread of the pest.

NWS does not pose a risk to food safety and USDA’s Food Safety and Inspection Service ensures the nation’s food supply is safe. After the re-emergence of NWS in Mexico in November 2024, the Swine Health Information Center has closely monitored NWS spread, hosted a webinar on the pest, and developed a new fact sheet for swine producers and other industry stakeholders.

Swine producers can prepare for NWS by understanding the fly’s behavior and life cycle, identifying production and housing conditions that increase the risk of myiasis, implementing effective biosecurity, environmental, and wound management practices, knowing the response procedures for suspected infestations, and developing an NWS disaster management plan. Monitoring for clinical signs of NWS in swine remains critical, including nonhealing wounds, wounds with a foul odor, biting or licking at wounds, depressed behavior, inappetence, and visible larvae in wounds. Any suspect cases of NWS should be reported immediately to state and/or federal animal health officials.

For more information, NWS resources are available here:

Since November 2024, USDA has increased monitoring, prevention, and mitigation practices to address this emerging disease threat to domestic livestock. Those efforts include ongoing aerial dispersion of sterile NWS flies in Mexico and along the Texas border to curb fly population growth as well as active surveillance for NWS flies and cases in border states.

Read about NWS being discovered in Mexico in 2024 here.

Visit the Mexican government NWS dashboard here for the latest reporting data.

The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Megan Niederwerder at [email protected] or Dr. Lisa Becton at [email protected].

June 10, 2026

Published by Megan Niederwerder at June 10, 2026