USDA Confirms Rise to 15 New World Screwworm Cases in Texas as Sterile Fly Releases Intensify

The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported on June 21, 2026, three additional detections of New World screwworm (NWS) in Texas—a lamb in Crockett County and two calves in Edwards County—bringing the national total to 15 since the first confirmed case on June 3 in Zavala County.[1][2] Official USDA announcements detail aggressive containment measures, including weekly releases of tens of millions of sterile flies to disrupt the parasite’s reproductive cycle, noting that multiple generations (averaging 21 days each) are required for population decline.[3]

The outbreak has prompted a coordinated federal-state response under Texas Governor Greg Abbott’s disaster declaration, with quarantines, enhanced surveillance, and FDA emergency authorizations—including generic nitenpyram for treating infested dogs and cats.[4] Historical context shows NWS was eradicated from the U.S. in 1966 via sterile insect technique, with a brief 2016–2017 Florida Keys incident in deer; the current northward spread from Mexico has triggered preemptive infrastructure investments, such as a new sterile fly facility in Edinburg, Texas.[5]

Beyond immediate animal health risks, analysts highlight potential economic ripple effects: a USDA-linked estimate projects up to $1.8 billion in damages to Texas livestock alone if unchecked, affecting beef, dairy, and related supply chains without direct food safety threats.[6] The response emphasizes One Health coordination involving wildlife monitoring and public reporting hotlines.