US prepares to import Brazil-made screwworm treatment

The federal response to New World screwworm is expanding again, this time with an imported treatment product. USDA APHIS said EPA has granted an emergency exemption allowing importation and use of Tanidil, a topical powder manufactured in Brazil, as U.S. officials prepare for additional cases and try to prevent the parasite from becoming reestablished in domestic animals and wildlife. APHIS said the product will be brought in under Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act and held through the National Veterinary Stockpile. (aphis.usda.gov)

The move comes just weeks after USDA confirmed the first U.S. New World screwworm case in decades, in a calf in Zavala County, Texas, on June 3, 2026, followed by additional detections that triggered broader surveillance and response measures. APHIS has described New World screwworm as a major threat to livestock, wildlife, pets, and occasionally people, and Texas activated a statewide response that included disaster proclamations and field operations. Federal agencies have also been building out a larger preparedness framework through screwworm.gov and related response planning. (direct.aphis.usda.gov)

The practical change here is treatment capacity, though not right away. APHIS said Tanidil is not currently available in the U.S., so the agency must first order, import, and relabel it, a process expected to take about 90 to 100 days. Some states may also require state-level registration before the product can be used there. Once available, Tanidil will be distributed only through APHIS, in coordination with state animal health officials and federally recognized tribal agencies, rather than through normal private channels. Authorized users could include veterinarians, quarantine personnel, certified applicators at livestock and game facilities, zoo and wildlife staff, and others working under government supervision. (aphis.usda.gov)

APHIS also drew a clear line between Tanidil and Negasunt, another topical powder already under federal emergency authorization. Tanidil is regulated through EPA because of its pesticide pathway, while Negasunt, which includes an added antibiotic, is regulated by FDA. FDA issued its emergency use authorization for Negasunt Powder on April 27, 2026, for prevention and treatment of New World screwworm in multiple species, with human safety precautions and food animal withdrawal restrictions, including a 28-day slaughter withdrawal and a prohibition on use in animals producing milk for human consumption. Both products, however, are being funneled through the National Veterinary Stockpile rather than broad commercial release. (aphis.usda.gov)

Expert commentary suggests the treatment import is only one part of a much larger control effort. NC State entomologist Maxwell Scott said the current sterile fly pipeline is still heavily dependent on a single rearing facility in Panama, with flies shipped north as sterilized pupae and then distributed from the USDA facility in Edinburg, Texas. That underscores how much the response still depends on logistics, not just drug access. Scott also pointed to newer biology-based control approaches under development, but those are not yet the frontline answer. In other words, Tanidil may help strengthen field response, but it doesn’t replace surveillance, wound management, movement controls, and sterile insect technique. (phys.org)

Why it matters: For veterinary professionals, especially those in food animal, equine, mixed animal, wildlife, and public practice, the Tanidil exemption signals that federal agencies are trying to widen the treatment toolbox before a larger wave of cases arrives. It also reinforces that access will remain tightly controlled and operationally complex. Clinicians should expect a patchwork environment in which product eligibility depends on species, geography, and whether a case sits inside an APHIS-defined response zone. Companion animal practices should note that Tanidil is not for domestic pets or birds, while livestock and wildlife responders may need to coordinate directly with state or federal officials to access stockpiled products. (aphis.usda.gov)

That matters at the practice level because New World screwworm response is quickly becoming less about a single diagnosis and more about systems readiness: recognizing suspicious wounds early, knowing reporting pathways, understanding which emergency-authorized products apply to which species, and preparing pet parents and producers for strict handling and follow-up requirements. AVMA and FDA have both been directing veterinarians to centralized guidance as the response evolves, reflecting how fast the regulatory picture is changing. (fda.gov)

What to watch: The next signals will be APHIS updates on when Tanidil physically arrives in the U.S., which states complete registration, whether additional domestic cases continue to move north or cluster near the border, and how treatment access intersects with sterile fly deployment and other containment measures over the next three months. (aphis.usda.gov)