New World Screwworm: What Beef Producers Need to Know

The New World Screwworm (NWS) is a deadly parasite that attacks warm-blooded animals, including cattle. After being eradicated from the U.S. in 1966, New World screwworm has remained a threat in other parts of the Americas, with recent outbreaks in Central America and Mexico showing the risk of reintroduction.¹ On June 3, 2026, the U.S. Department of Agriculture (USDA) officially announced that New World Screwworm has been confirmed in southern Texas.² The current situation regarding NWS can change rapidly.

NWS is an animal health issue, not a food safety concern and is not transmitted through meat products.³

The United States Department of Agriculture Food Safety and Inspection Service (USDA FSIS) is the regulatory agency responsible for ensuring that the nation’s commercial supply of meat, poultry and egg products is safe and properly labeled. Any evidence of screwworm infection would be identified during these inspection processes, and adulterated product from the affected animal would not be allowed to enter the food supply.⁴

All imported meat and poultry products must first meet U.S. Customs and Border Patrol and USDA APHIS animal health requirements and are subsequently reinspected at a federally inspected facility prior to entry into U.S. commerce.⁴

Any animal pharmaceutically treated for NWS is held for testing to ensure there are no medication residues present. USDA FSIS will remove any animal from food production if residues are found.⁵

Why it Matters Now:

• On June 3, 2026, the U.S. Department of Agriculture (USDA) officially announced that New World Screwworm has been confirmed in southern Texas.²
• NWS is regularly found in Cuba, Haiti, the Dominican Republic and South America with cases now spreading as far north as Mexico.¹
• The U.S. and Panama are maintaining a barrier zone in eastern Panama to stop its northward spread.⁶
• In 2023, an unprecedented number of NWS cases were reported in Panama, followed by confirmed cases in every Central American country and Mexico.⁶
• NWS can cause millions in production losses and is harmful to humans as well.⁶
• Prior to eradication, the pest cost the U.S. livestock industry over $100 million annually⁷, and reintroduction could lead to major economic and animal health impacts.⁸

What to Watch for:

• Irritated behavior, head shaking or the smell of decay.
• Maggots in wounds and visible egg masses or larvae by day 3.⁸
• NWS maggots burrow into live tissue, causing severe pain, withdrawal and loss of appetite.⁸

If You Suspect NWS:

• Report it immediately to a veterinarian, State Animal Health Official or the USDA.⁸

Quarantine Risk:

• USDA response plans include quarantines and movement restrictions in affected areas.⁹
• Permits may be required to move livestock, with inspections for wounds and myiasis.⁹
• Control decisions will be based on science, spread risk and environmental factors.⁹

Bottom Line:

Early detection and prevention are key. NWS poses a serious threat to livestock, wildlife and even people. Staying informed and reporting concerns helps protect U.S. cattle herds and ranching livelihoods.

For USDA updates regarding NWS, visit NCBA’s website for more information.