U.S., Mexico reach agreement to resume NWS eradication efforts

On April 30, Mexican officials announced they would eliminate restrictions on U.S. Department of Agriculture (USDA) aircraft and waive customs duties on equipment needed to aid in eradication efforts of the New World screwworm (NWS).

While the agreement ensures ports will remain open to livestock imports, U.S. Secretary of Agriculture Brooke Rollins made it clear, if at any time the terms are not upheld, port closure would be revisited. 

“I am happy to share Mexico has continued to partner in emergency efforts to eradicate NWS,” Rollins states in an April 30 press release. “This pest is a devastating threat to both of our economies, and I am pleased to work together with Mexico in good faith to protect the livelihoods of our ranchers and producers who would have been hurt by this pest.”

“At USDA we are working every day to keep pests and disease from harming our agricultural industry. I thank our frontline USDA staff and their counterparts in Mexico for their work to ensure NWS does not harm our livestock industry,” she adds.

Background information

The USDA was notified NWS was detected in Mexico in November of 2024.

According to the USDA’s Animal and Plant Health Inspection Service (APHIS), NWS is a devastating pest endemic in Cuba, Haiti, the Dominican Republic and countries in South America, with cases spreading north to Costa Rica, Nicaragua, Honduras, Guatemala, Belize, El Salvador and Mexico.

Larvae of the fly are known to burrow into the flesh of living animals, often resulting in death, and the pest can infest livestock; pets; wildlife; birds, on occasion and, in rare cases, people.

NWS was eradicated from the U.S. in 1966, and the USDA has been working diligently ever since to increase surveillance and other measures to mitigate reintroduction, including the sterile insect technique. 

This technique requires the continuous release of sterile male screwworm flies into the population. These sterile flies breed wild screwworms, resulting in unviable offspring, which eventually results in species eradication. 

Unfortunately, according to the USDA, Mexican authorities were recently failing to uphold their end of the agreement toward eradication efforts by disrupting the planes carrying sterile male flies by refusing pilots permission to land and instituting customs duties on the sterile flies and other required equipment.

“We have received multiple reports critical flights carrying sterile flies have been denied permission to land, faced bogus paperwork issues and been charged high customs fees,” states National Cattlemen’s Beef Association (NCBA) Senior Vice President of Government Affairs Ethan Lane in an April 26 press release. “As a result, we have lost significant time and investment which has allowed these dangerous pests to spread unchecked into southern Mexico.”

“In light of those reports, NCBA met with the Mexican Embassy to deliver the message the Mexican government needs to be a partner on eradicating screwworms to protect both animal and human health,” Lane continues. “It’s time for Mexican authorities to act, and we appreciate Rollins standing with American and Mexican cattle producers who want to see this pest stopped dead in its tracks.” 

USDA demands

Mexico’s announcement comes after Rollins sent a letter to Mexico Secretary of Agriculture Julio Antonio Berdegue Sacristan on April 30 demanding a resolution to the country’s restrictions.

In the letter, Rollins noted if issues were not resolved by April 30, the U.S. would restrict livestock imports, specifically on cattle, equine and bison, in an effort to protect the U.S. ag industry.

“We are now at a critical inflection point in our shared campaign against this pest, and I am very concerned about our collaboration,” the letter reads. “The outbreak in southern Mexico continues to expand, and every day that passes without full deployment of sterile insect technique operations represents a lost opportunity to contain this pest and prevent its spread beyond the Isthmus of Tehuantepec.”

Rollins called on Mexican authorities to engage customs and other relevant federal officials to help facilitate operations by the USDA’s contractor Dynamic Aviation for a minimum of one year, but preferably as long as needed. 

She also called for clearance and a waiver of import duties for aircraft ports and sterile flies and for Mexico to designate a high level point of contact in the government to work directly with USDA.

“Time is of the essence,” she states in the letter. “Every delay in granting full operational authority and eliminating customs barriers undermines our collective ability to carry out this emergency response. We cannot afford to continue operating at partial strength. The situation requires immediate attention and decisive coordination at the highest levels of your government.”

Mexico’s positive April 30 announcement is a step in the right direction towards eradicating NWS and the potential havoc it could wreak on livestock producers in both countries.

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.