Multiple departments in the Trump administration are working to combat the proliferation of a flesh-eating parasite quickly spreading northward through Central America and threatening the United States’s food supply.
U.S. Agriculture Department Secretary Brooke Rollins said in a statement on Tuesday that her Department is working closely with the Department of Health and Human Services to stave off infestations caused by the New World Screwworm, a fly that lays its eggs in openings or wounds in warm-blooded animals.
“Our cattle ranchers and livestock producers are relying on the Trump administration to defend their livelihoods,” said Rollins. “Stopping this pest is a national security priority, and we are linking arms across President Trump’s Cabinet to defend our borders and push back this threat.”
On Tuesday, the Food and Drug Administration granted emergency-use authorization for veterinarians to use animal drugs to treat and prevent infestations of New World screwworm. The emergency action was necessary because there are no currently FDA-approved treatments or medications for the parasitic disease.
Here is everything you need to know about the New World screwworm and its ramifications for the U.S. food supply.
What is New World screwworm?
New World screwworm infestation occurs when NWS fly larvae burrow into the flesh of warm-blooded animals, according to the Centers for Disease Control and Prevention.
The CDC says any opening, such as “the nose, mouth, or eyes, umbilical cord of a newborn animal, or genitals, will attract the female flies” to lay their eggs. A wound the size of a tick bite is large enough for a screwworm to burrow into.
Symptoms of an NWS infection in animals and humans include unexplained skin lesions that do not heal or worsen over time, bleeding or foul-smelling odor from open sores, and seeing maggots around or in open sores.
NWS was once endemic across the southern United States, but an eradication program was started in 1957 under the USDA’s Agricultural Research Service. The disease was successfully eradicated from the U.S. in 1996, and Mexico and several Central American countries have been declared disease-free since 1984.
An outbreak of the disease was identified in the Florida Keys in October 2016 and was contained within five months by March 2017.
When did the new outbreak start?
According to the USDA, NWS detections in Panama rapidly increased in 2023 from an average of 25 cases per year to more than 6,500 cases in 2024.
NWS has since been detected in several Central American countries, including Costa Rica, Nicaragua, Honduras, Guatemala, Belize, and El Salvador. The disease has also spread throughout Mexico’s southernmost states across the Yucatan Peninsula.
On Tuesday, Belize health authorities confirmed its first human case of NWS infection in a 21-year-old male. The country’s health minister reported that the patient is responding well to treatment and should be released within the next few days.
What is the threat to the US food supply?
USDA and HHS say the risk of human infections in the U.S. is very low, but livestock, such as cattle, horses, and bison, are most at risk.
The screwworm’s 10- to 30-day lifespan allows an infestation to spread quickly throughout a herd, causing significant financial losses for farmers and ranchers and severe pain for animals.
According to the USDA, NWS infections in livestock in the U.S. during the twentieth century cost the agriculture industry an average of $20 million annually.
When USDA Secretary Brooke Rollins shut down cattle, horse, and bison imports through the U.S.-Mexico border in May, detections of NWS infections were roughly 700 miles away from the border. But last month, the disease was detected approximately 370 miles from the U.S. southern border, indicating it’s moving fast.
How is the FDA helping the USDA?
The FDA’s granting of emergency-use authorization for animal drugs to treat and prevent screwworm infections will enable veterinarians to be more proactive in treating livestock.
The FDA’s Center for Veterinary Medicine is working with the USDA and the Environmental Protection Agency to monitor the spread of NWS throughout the continent and prepare for infestations on U.S. soil.
The agency said it has opened multiple regulatory pathways for pharmaceutical companies to quickly submit drugs for permanent approval to treat the animal infection.
FDA Commissioner Dr. Marty Makary said Tuesday that the federal government’s priority is “to safeguard both animal health and the nation’s food supply.”
“FDA is acting swiftly and responsibly to help ensure we have the necessary tools to prevent and control New World Screwworm, minimizing risks to agriculture and public health,” Makary said.
What else is USDA doing?
Rollins introduced a five-prong plan in June to prevent the spread of NWS, which includes working with Mexico to combat the spread of the parasite further northward.
Rollins met with Gov. Greg Abbott (R-TX) on Friday to meet with stakeholders, including ranchers, state veterinarians, and environmental protection officials.
During her visit, Rollins and Abbott announced a $750 million investment for a new breeding facility in Edinburg, Texas, that will produce roughly 300 million sterile screwworm flies per week to release into the environment.
This technique of breeding sterile male flies decreases the population of pests in the wild by having non-fertile males mate with females in the environment.
Russel Boening, President of the Texas Farm Bureau, called the screwworm threat “real and urgent” on Friday, adding that the facility’s construction is “essential to prevent irreversible harm to the agricultural economy and our nation’s food system.”
