The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the detection of New World Screwworm (NWS) in two calves in Zavala County, Texas. While there are no detections in Arkansas at this time, livestock and animal owners should stay alert and take preventative action.
What is New World Screwworm?
NWS is a dangerous parasitic fly whose maggots feed on the living tissue of warm‑blooded animals. Without quick treatment, infestations can cause severe tissue damage and can be fatal. All animals are at risk, including livestock, pets, wildlife, and less commonly, people and birds.
What to Look For
Producers and animal owners should watch for wounds that fail to heal, foul‑smelling discharge, tissue damage, or visible maggots in or around a wound. Animals may also appear lethargic, lose appetite, or show signs of pain. These symptoms can progress quickly, so prompt attention is critical.
High-Risk Situations
Procedures such as branding, castration, and dehorning, as well as birthing events where navels remain open, increase the risk of infestation. Injuries caused by predators, surgical sites, and stress from transport or sale events can also create opportunities for NWS to establish in an animal.
If You Suspect NWS
If NWS is suspected, isolate the affected animal immediately and avoid moving any animals off the premises, as movement can rapidly spread the pest. Contact your veterinarian or the Arkansas Department of Agriculture (501-225-1598; [email protected]) right away to report the situation and receive instructions for next steps, including sample submission and treatment.
Prevention
Preventive measures are the most effective defense. Producers and animal owners should monitor animals daily during fly season, treat all wounds promptly, maintain clean facilities, reduce fly breeding areas such as accumulated manure, and use consistent fly control practices. Keeping animals healthy and minimizing wounds greatly reduces the chance of infestation.
Regulatory Response
If NWS is confirmed in Arkansas in the future, state and federal officials will implement a coordinated response. This will include quarantines, movement restrictions, and the designation of surveillance zones to contain and eliminate the pest. These measures are designed to protect animal health and prevent the spread of NWS.
Current Situation in Texas
USDA and Texas officials are taking immediate action to contain and eradicate NWS from the United States including implementing quarantines, movement controls, and active surveillance in the affected area as well as increasing the targeted release of sterile NWS flies and trapping for NWS flies.
Current Situation in Arkansas
There has not been a confirmed case of NWS in Arkansas at this time. Movement of animals into Arkansas from the affected area in Texas will be restricted according to established federal NWS response guidance and a state entry permit will also be required for those animals (see https://ar.accessgov.com/animal-health-division/Forms/Page/animal-health-division/entrypermit/1).
Additionally, all warm-blooded animals from Texas must be accompanied by an Interstate Certificate of Veterinary Inspection (iCVI) dated within 7 days of entry into Arkansas and must include the following statement: “All animals were inspected and found free of evidence of NWS infestation.” Group-housed food producing animals may be visually inspected in their group settings according to federal NWS response guidance. Individual inspection is required for all other animals.
Resources
- U.S. Department of Agriculture: https://www.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/stop-screwworm
- NWS Response Playbook: https://www.aphis.usda.gov/sites/default/files/nws-response-playbook.pdf
- FDA: https://www.fda.gov/animal-veterinary/safety-health/new-world-screwworm-information-veterinarians
- American Veterinary Medical Association: https://www.avma.org/resources-tools/one-health/veterinarians-and-public-health/new-world-screwworm