New World Screwworm Draws Near, NMPF Prepares
April 1, 2026
As spring temperatures rise, the threat of New World screwworm making its way into the United States is also increasing. NMPF is working with agencies and stakeholders to ensure dairy preparedness.
Infestations continue to push north toward the U.S.-Mexico border, with the closest currently active case about 150 miles from Texas; meanwhile, sterile flies are being released in Texas up to 50 miles from the Mexican border to help suppress populations before they can reach American livestock.
NMPF brought several key partners together for a webinar March 16 to share the latest on New World screwworm and what it means for U.S. dairy.
Three experts, Dr. Adis Dijab, associate deputy administrator for APHIS Veterinary Services, Dr. Sonja Swiger, professor and extension entomologist Texas A&M AgriLife Extension, and Dr. T.R. Lansford III, deputy executive director and assistant state veterinarian at the Texas Animal Health Commission, walked through signs and symptoms of New World screwworm in livestock, the current status of the pest and some practical steps farmers can take to stay ahead of it.
The experts also shared what treatment options are currently available for livestock and gave an overview of potential cattle movement requirements or restrictions in the event of an outbreak in the United States.
USDA and state agencies will take the lead in managing any outbreak. NMPF has provided feedback to USDA’s Animal and Plant Health Inspection Service on its emergency response plans for a U.S. screwworm infestation and USDA is taking that feedback into account to incorporate in its next response playbook draft.
During an outbreak, USDA handles movement between states, and individual states can add their own rules for moving livestock within their borders. Farmers can expect that animals will be subject to quarantine and movement restrictions in the areas closest to the infestation, including pre-movement animal health inspection and treatment when appropriate, based on standardized continuity of business New World screwworm animal health certification guidance. Most farmers should still be able to move their animals if they stick to the rules around inspections, treating wounds, paperwork and good biosecurity.
FDA has expanded animal drug treatment options for New World screwworm through Emergency Use Authorizations. Most recently, FDA issued an EUA March 10 for a new topical spray for lactating dairy cows that comes with only a 10-day milk withdrawal time. This is the first drug authorized for use to treat New World screwworm in lactating cattle.
NMPF will continue working with federal and state partners to ensure dairy farmers have the tools and support they need to keep their herds healthy.
