The US Department of Agriculture’s Animal and Plant Health Inspection Service confirmed the detection of a New World screwworm (NWS) in a bovine in Zavala County, Texas. NWS is a serious pest that affects livestock, pets, wildlife, and less commonly, people and birds. NWS larvae (maggots) burrow into the flesh of living animals, causing serious damage to livestock and economic losses. 

The affected animal is a 3-week-old calf and larvae were identified in its umbilical area. To date, there have been no further detections.

“All models showed New World screwworm entering the country in 2025; however, thanks to the hard work across the entire Trump administration and our industry, state, and local partners, we were able to buy time for this moment. Protecting our livestock industry is a national security issue of the utmost importance, and USDA is wasting no time in taking action,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “USDA invested heavily in the tools needed to eliminate NWS ever since cases started increasing in Central America and Mexico. The United States has defeated this pest before, and we will do it again.”

USDA and Texas officials are taking immediate action to contain and eradicate NWS from the United States, following the strategies and actions outlined in the NWS Response Playbook. This includes: 

• Forming a unified Incident Command Team with the Texas Animal Health Commission and deploying response personnel to the area;
• Establishing a 20 km infested zone around the detection and implementing quarantines, movement controls, and surveillance in this area;
• Expediting targeted release of sterile NWS flies by immediately deploying ground release chambers in the area, in addition to the 4 million sterile flies per week already being released aerially in the area; 
• Increasing trapping for NWS flies along the border and just outside of the dispersal area;
• Implementing NWS surveillance and management strategies in wildlife; and
• Conducting targeted outreach in the local area.

Additionally, USDA’s National Veterinary Stockpile stands ready to assist and will provide resources including treatments, equipment, and logistics support the response as needed.

USDA will continue to work with state departments of agriculture, animal health officials, industry, and producers to mitigate economic impacts of restrictions as much as possible, including negotiating with our trading partners to regionalize any trade restrictions on live animals, limiting them to defined geographic areas.  

NWS maggots can infest livestock and other warm-blooded animals, including in rare cases people. They most often enter an animal through an open wound and feed on the animal’s living flesh.  

USDA urges residents in the area to check their pets and livestock for signs of NWS. Look for draining or enlarging wounds and signs of discomfort. Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals. If you suspect your animal is infected with screwworm, contact your state animal health official or USDA area veterinarian in charge immediately. 

While not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted screwworm, seek immediate medical attention. 

The US food supply is safe. Screwworms do not infest meat, fruits, vegetables, or other food sources. USDA’s Food Safety and Inspection Service (FSIS) ensures that the nation’s commercial supply of meat, poultry, and egg products is safe and properly labeled. Under the Federal Meat Inspection Act (FMIA), FSIS inspection personnel must inspect all eligible animal species unless they are exempt or covered by a state inspection program.

Any evidence of screwworm infestation in an animal would be identified during these inspections, and any contaminated product from an affected animal would not be allowed to enter the food supply. 

For more than a year, USDA has led a unified response to NWS. As the lead coordinating agency, USDA has deployed advanced surveillance systems and supported robust cross-border response efforts in Mexico and Central America to combat the pest and push NWS away from the United States. These efforts have bought time for USDA to increase domestic preparedness efforts. 

Industry response

The US Cattlemen's Association commends APHIS and the Texas Animal Health Commission for their swift response to this potential detection and for their extensive work on-the-ground to hold off the reemergence of New World screwworm through 2025 and into the first half of 2026. USCA emphasized that early activation of personnel in the region, close coordination with state and local partners and continued focus on prevention, early detection and rapid response have bought producers and animal health officials critical time to prepare for a situation just like this.

USCA welcomes USDA Secretary Rollins’ commitment that USDA will remain in constant communication with industry stakeholders as this situation develops. USCA noted that transparent updates from USDA, APHIS and TAHC are vital to ensure that cattle producers have the information they need to safeguard their herds, implement any recommended biosecurity measures and coordinate effectively with animal health officials.

USCA’s Animal Health Committee is actively engaged on this issue and is in close contact with federal and state animal health officials as the situation evolves. USCA’s priority remains the protection of animal health, the integrity of the US cattle herd and the long-term viability of domestic livestock production.

Meat Institute President and CEO Julie Anna Potts said, “American consumers need to know that New World screwworm is not a food safety concern. Meat and poultry products are safe to consume. Our first priority is to protect the health of the nation’s livestock. We are encouraging members of the Meat Institute to work with local, state and federal authorities to detect and irradicate the pest.

“We will look to USDA to brief industry stakeholders and call on them to consider allowing low risk terminal movements for slaughter to ensure animals continue to be processed. It is important for state animal health organizations to follow USDA’s NWS Response Playbook.”

Learn more about New World screwworm at Screwworm.gov

Source: USDA FSIS