USDA confirms two additional cases of New World screwworm in the United States; New cases involve a calf and a dog

The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed two additional cases of New World screwworm (NWS) in the United States (June 8, 2026)– a calf in La Salle County, Texas, and a dog in Andrews County, Texas.

Epidemiological investigations are ongoing for both cases. A veterinarian in Andrews County submitted the samples from the infested dog. Details on this case will be shared as they are available, but early reports indicate the dog was recently in Mexico.

NWS is a serious pest that threatens livestock, pets, wildlife, and, in rare cases, people. The larvae burrow into the living tissue of animals, causing severe wounds, animal suffering, and significant economic losses.

“Over the past week, USDA has identified and expeditiously confronted four confirmed detections of New World screwworm. While we address these instances that require immediate attention, and continue to sample suspected cases, we are simultaneously working to eradicate the pest entirely,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “We need the partnership of animal owners across the region – please stay vigilant, check your animals closely, and report anything that looks suspicious. Together, we can protect our livestock, our communities, and the health of animals nationwide.”

USDA and TAHC Response 

USDA and the Texas Animal Health Commission (TAHC) continue to lead an aggressive unified response, with a total of 75 people actively responding on the ground and hundreds of additional people around the country providing laboratory diagnostics, logistics, treatment distribution, air operations, outreach, operational planning, and resource support for the response. APHIS and TAHC will continue to surge additional trained personnel as needed to ensure an effective response.

For each new case, USDA and TAHC implement actions outlined in the NWS Response Playbook, including:

• Establishing and maintaining a 20km infested zone with quarantines, movement controls, and heightened surveillance around confirmed detections
• Increasing trapping along the border and outside the dispersal zone
• Conducting surveillance and management strategies in wildlife
• Implementing targeted outreach to local producers, veterinarians, and communities

Intensified Sterile Fly Releases

USDA continues to release sterile flies over and just outside of the infested areas. To ensure sterile fly release operations can be deployed to affected areas in Texas and in northern Mexico near the border as quickly and efficiently as possible, USDA has activated the sterile fly dispersal facility at Moore Air Base in Edinburg, Texas. Sterile pupae arrived at the facility on Friday, and aerial dispersal flights originating from the base will begin tomorrow.

Because it is important to continue ongoing surveillance efforts while releasing sterile insects, it is possible that sterile NWS flies could be caught and/or reported. To ensure officials can tell the difference between sterile and wild NWS flies, USDA dyes the sterile pupae, and the dye transfers to the sterile flies when they hatch. The fluorescent green or orange dye glows under UV light and may also be visible to the naked eye. If a sterile fly is captured in a trap, this dye allows animal health officials to quickly rule the fly out as a threat.

Guidance for Pet and Livestock Owners

USDA urges everyone in the area to check animals for:

• Draining or enlarging wounds
• Maggots or egg masses
• Signs of discomfort
• Lesions in body openings (nose, ears, genitalia, umbilical area)

Anyone who suspects a screwworm infestation should immediately contact their veterinarian, state animal health official, or USDA. USDA has established this contact page to ensure everyone can easily find the correct contact information for these groups. In Texas, report suspected cases in livestock directly to TAHC officials by finding your closest area office here. 

Though rare in people, anyone who notices a suspicious lesion should seek immediate medical care.

Food Safety

The U.S. food supply remains safe. NWS does not infest meat, fruits, vegetables, or other food products. Any affected animal would be identified during USDA Food Safety and Inspection Service inspection, and no contaminated product would enter commerce.

Transparency and Sustained On the Ground Response

USDA and its Texas partners are operating with full transparency, committed to keeping producers, veterinarians, local communities, and the public informed as new information becomes available. USDA will continue to provide timely updates and maintain a visible, sustained presence in affected areas.

More information about New World screwworm is available at Screwworm.gov.