New World Screwworm

New World screwworm (Cochliomyia hominivorax, or NWS) is a devastating pest in which larvae, or maggots, burrow into the flesh of living animals, causing serious and often deadly damage. NWS can infest livestock, pets, wildlife, and occasionally birds and, in rare cases, people.

Effective Immediately - Updates to Maryland Import Requirements d/t Texas and New Mexico New World Screwworm Detections

Import Requirements: Except where more stringent requirements are adopted herein, all animals being imported into Maryland from a high-risk area must meet the requirements for the prevention of disease located in MD Code, Agriculture, Title 3, Regulation of Livestock and Poultry.

All warm-blooded animals, including dogs, cats, and birds originating from the states of Texas and New Mexico must be accompanied by an Official Certificate of Veterinary Inspection (OCVI) issued within 72 hours of movement. Hatching and table eggs are exempt from these requirements.

The OCVI must document that all animals listed on the OCVI have been inspected and found free of contagious and infectious disease and pests, including New World Screwworm (NWS).

No alternative movement documents, such as an NPIP 9-3, will be accepted in lieu of an OCVI.

The OCVI must contain a statement from the accredited veterinarian attesting that:

“All animals listed on the OCVI have been examined within 72 hours of movement and none have been found to have a wound infested, or potentially infested, with New World Screwworm.”

All warm-blooded animals that have wounds that are not infested with NWS larvae can be imported into Maryland provided that the following requirements are met:

Any animal with a wound must be treated with a product listed as having an approved, conditionally approved, or emergency use authorization (EUA) for NWS by FDA.

The effective treatment for NWS must be administered in accordance with the following:

Oral or injected treatments must be administered no less than 12 hours prior to entry into Maryland.

Topical treatments must be administered no less than 72 hours prior to entry into Maryland.

The wound location and treatment must be documented on the OCVI.

No warm-blooded animals with NWS infestation are allowed to be imported into Maryland.

The MDA Animal Health program will continue to monitor detections in Texas and New Mexico. Maryland import requirements will be amended or lifted as appropriate.

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Four Additional Cases of New World Screwworm - 3 Confirmed in Texas and 1 Confirmed in New Mexico

As of Monday, June 8, 2026, there are 3 additional NWS cases in Texas. The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed three additional cases of New World screwworm (NWS) in Texas - a calf in Zavala County, a calf in La Salle County, and a goat in Gillespie County. USDA and the Texas Animal Health Commission are working as quickly as possible to gather additional details about the case, establish surveillance and testing in the area, and share outreach materials and information.

In addition, USDA APHIS has confirmed a case of NWS in a dog in Lea County, New Mexico. This is believed to be an isolated case; however, because the dog’s recent travel and exposure history remain unknown, USDA and New Mexico have initiated inspection of additional animals in the dog’s home and increased outreach in the area while continuing to investigate the animal’s movement history.

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.

“This situation is evolving, and we expect new information to emerge as our investigation continues. USDA is committed to sharing what we learn quickly, accurately, and transparently so animal owners and local communities have the information they need to stay vigilant,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “We are working closely with our partners in New Mexico, Texas, and across the region to ensure we identify, contain, and respond to any potential cases as swiftly as possible.”

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

USDA and New Mexico Response

APHIS and New Mexico state officials are working together closely to implement actions outlined in the NWS Response Playbook, including:

continuing the epidemiological investigation,
sampling additional animals in the household,
fly trapping,
preparing for release of sterile insects should it be needed, and
conducting outreach in the area to encourage reporting of additional suspect cases

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)

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 and New Mexico 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.

Anyone who suspects a screwworm infestation should immediately contact the Maryland State Veterinarian or the USDA Area Veterinarian in Charge. USDA has established this contact page to ensure everyone can easily find the correct contact information.

MDA Animal Health has updated the import requirements for warm-blooded animals entering Maryland from Texas or New Mexico and for animals returning to Maryland after travel to either state.

The updated import requirements are attached and available at MDA Animal Health.

Please note that many states may be implementing movement restrictions or new import requirements for animals during this outbreak. Always verify the destination state's import requirements to ensure compliance with all applicable regulations.

The Maryland Department of Agriculture, Animal Health Program may be reached at 410-841-5810 or via email at [email protected].

Preventing NWS from entering the United States is vital to protect our livestock industry, economy, and food supply chain.

For a more indepth look at the New World screwworm including life cycle please watch this webinar from USDA APHIS.

*Photo: USDA APHIS