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.

For the latest New World Screwworm detection updates and related information, visit the USDA website here!

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 five days prior to entry into Maryland.

Topical treatments must be administered no less than five days 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.

Mandatory Reporting of Suspected New World Screwworm (NWS)

Prompt reporting of any suspected or potential NWS cases to the State Veterinarian is required. Licensed veterinarians, livestock producers, livestock dealers, livestock markets, wildlife rehabilitators, municipal animal control officers, animal shelthers, animal rescue organizations, fairs, shows, exhibitions, commercial animal exhibits (e.g., animal experiences such as goat yoga) and pet stores must immediately report any evidence of maggot infestation in a warm-blooded animal to the MDA Animal Health Program.

MDA Animal Health personnel will coordinate the collection of larval samples for submission to the Maryland Animal Health laboratories or another USDA-approved labratory for identification. Prompt reporting and laboratory confirmation are critical to ensuring a rapid response and preventing the establishment and spread of New World Screwworm.

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.

UPDATE: July 6, 2026

Subject: 32 Confirmed Cases of New World Screwworm - 31 Confirmed in Texas and 1 Confirmed in New Mexico

As of Monday, July 6, 2026 there are a total of 32 confirmed cases of New World Screwworm (NWS). The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the most recent case in a sheep on July 3, 2026 in Crockett County, Texas.

Eighteen cases are considered active. Active animal cases are those that involve ongoing disease mitigation efforts on the individual animal until it is free of NWS myiasis, including treatment and wound management of the infested animal.

Fourteen cases are considered inactive. Inactive animal cases refer to situations where mitigation activities are no longer required on that animal. Either the animal has fully recovered, with myiasis resolved and treatment completed, or appropriate measures have been taken to prevent the spread of NWS, such as appropriate carcass management of a deceased infested animal.

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.

NWS Response

USDA, the Texas Animal Health Commission (TAHC), and the New Mexico Livestock Board (NMLB) continue to lead an aggressive unified response, with over 100 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 will continue to surge additional trained personnel as needed to ensure an effective response.

For each new case, USDA, TAHC and NMLB 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.

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, Texas, and New Mexico partners are operating with full transparency. They are 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.

Maryland NWS Precautions

Prompt reporting of any suspected or potential NWS cases to the State Veterinarian is required.Licensed veterinarians, livestock producers, livestock dealers and livestock markets, wildlife rehabilitators, municipal animal control officers, animal shelters, animal rescue organizations, fairs, shows, and exhibitions, commercial animal exhibits (e.g., animal experience events such as goat yoga), and pet stores must immediately report any evidence of maggot infestation in a warm-blooded animal to the Maryland Department of Agriculture (MDA) Animal Health Program.

MDA Animal Health personnel will coordinate the collection of larval samples for submission to the Maryland Animal Health Laboratories or another USDA-approved laboratory for identification. Prompt reporting and laboratory confirmation are critical to ensuring a rapid response and preventing the establishment and spread of New World Screwworm.

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 Maryland import requirements are attached and are also available on the MDA Animal Health website. Import requirements may be revised or lifted as the situation evolves. To ensure compliance with all applicable regulations, please verify Maryland's current import requirements prior to the movement of animals into the state.

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].

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