U.S. adds screwworm treatments as cases near the border

Federal agencies are adding another treatment option to the U.S. New World screwworm response as the parasite continues to move through Mexico. On April 27, 2026, the EPA granted a Section 18 emergency exemption allowing USDA to import Tanidil, a topical powder made in Brazil, for prevention and treatment of New World screwworm. The same day, FDA issued an emergency use authorization for Negasunt Powder for multiple species, including cattle, swine, sheep, goats, horses, donkeys, mules, and captive wild and zoo mammals. Both products will be funneled through USDA APHIS and the National Veterinary Stockpile rather than the commercial market. APHIS says Tanidil will take about 90 to 100 days to import and relabel, and some states may still require their own registrations before it can be deployed. (aphis.usda.gov)

Why it matters: For veterinary professionals, this is a practical preparedness move, not a sign that New World screwworm is already back in the U.S. USDA says the pest is not currently present in the country, but cases in Mexico have moved close enough to the border to trigger a broader federal response that now includes sterile fly dispersal, port closures for livestock trade, and emergency access to treatment tools. If an incursion occurs, veterinarians could become part of a tightly controlled response in infested and surveillance zones, with specific safety, reporting, and distribution requirements. (direct.aphis.usda.gov)

What to watch: Watch for APHIS guidance on state registrations, stockpile deployment rules, and whether additional New World screwworm therapies or response zones are authorized in the coming weeks. (aphis.usda.gov)