Veterinary - New World Screwworm
USDA Announces Suspension of Live Cattle, Horse, and Bison Imports
On May 11, 2025, the United States Department of Agriculture (USDA) announced the suspension of live cattle, horse, and bison imports through U.S. ports of entry along the southern border, effective immediately. This is in response to the continued and rapid northward spread of New World Screwworm (NWS) in Mexico. Suspension of livestock transport is hoped to decrease the northern movements of livestock and in turn slow the spread of NWS northward through Mexico. USDA Animal Plant Health Inspection Service (APHIS) in conjunction with Customs and Border Protection will restrict the importation of live animal commodities originating from, or transiting Mexico. This live animal import suspension will be re-evaluated on a monthly basis.
USDA is working to limit the spread of NWS and to surveille the southern border. USDA Tick Riders will be monitoring both livestock and wildlife along the southern border for the presence of NWS. USDA is also working with Mexico to eradicate NWS in Mexico.
While measures have been taken to limit the spread of NWS spread is still possible through natural wildlife movements.
New World Screwworm flies can look very similar to houseflies and the maggots are impossible to tell apart from routine maggots in the field. The New World Screwworm maggot is much more aggressive; they cause extensive damage to wounds by feeding on healthy tissue. If you suspect New World Screwworm maggots in a wound call your local veterinarian or NCDA&CS at (919) 707-3250. New World Screwworm is a reportable disease in the United States.
For more information about New World Screwworm including history and previous outbreaks: New World Screwworm
New World Screwworm Fact Sheet: Pest Alert: New World Screwworm
For more information about the current outbreak: New World Screwworm Outbreak in Central America
CDC information page: About New World Screwworm Myiasis | Myiasis | CDC
USDA Press Release: Secretary Rollins Suspends Live Animal Imports Through Ports of Entry Along Southern Border, Effective Immediately | Home