US Secretary of Agriculture Brooke Rollins has announced the suspension of live cattle, horse, and bison imports through US ports of entry along its southern border due to “the continued and rapid northward spread” of New World screwworm in Mexico.
The suspension is effective immediately. The US Department of Agriculture (USDA) said that screwworm has been recently detected in remote farms, with minimal cattle movement, in the Mexican states of Oaxaca and Veracruz, about 700 miles away from the US border.
New world screwworm is a species of parasitic fly, the larvae (maggots) of which eat the living tissue of certain animals.
The USDA said that there has been “unacceptable northward advancement” of screwworm, and additional action must be taken to slow the northern progression of the parasitic fly.
The USDA Animal Plant Health Inspection Service (APHIS) in conjunction with Customs and Border Protection (CBP) will restrict the importation of live animal commodities originating from, or transiting through, Mexico.
This import suspension will persist on a month-by-month basis, until a significant window of containment is achieved, authorities said.
Any livestock currently in holding for entry into the US from Mexico will be processed normally. This includes an APHIS port veterinary medical officer inspection exam and treatment to ensure they are not carrying the parasite.
Rollins commented: “It is my duty to take all steps within my control to protect the livestock industry in the United States from this devastating pest.
“The protection of our animals and safety of our nation’s food supply is a national security issue of the utmost importance.
“Once we see increased surveillance and eradication efforts, and the positive results of those actions, we remain committed to opening the border for livestock trade,” Rollins added.
“This is not about politics or punishment of Mexico, rather it is about food and animal safety,” she said.
According to the USDA, suspending livestock transport through southern ports of entry will assist in the effort to limit northbound transport of screwworm through livestock commerce, and will allow the US to reassess whether current mitigation standards remain sufficient.
However, the USDA also noted that the spread of screwworm is also possible through natural wildlife movements, including wildlife that crosses over the US-Mexico border without impediment.
The first case of screwworm in Mexico was reported to US authorities in November 2024. When the fly larvae burrow into the flesh of a living animal, they cause serious, often deadly damage to the animal. Screwworm can infest livestock, pets, wildlife, occasionally birds, and, in rare cases, humans.
Over the last two years, NWS has spread north through Panama, Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize, and now Mexico, the USDA said.
