Growing Number of Infestations Highlights the Need for Early Detection and Strong Animal Health Measures
San Antonio, Texas, 20 July 2026 – A growing number of New World screwworm infestations has put animal health officials across Texas on high alert. According to the U.S. Department of Agriculture, 31 confirmed infestations have been reported in the United States, including 30 in Texas and one in New Mexico. State and federal agencies are working together to monitor the situation, contain the parasite, and protect livestock, pets, wildlife, and the agricultural economy.
The New World screwworm is not a typical worm but the larva of a fly. Unlike common maggots that feed on dead tissue, screwworm larvae invade healthy, living flesh through open wounds or natural body openings. If left untreated, the infestation can cause severe tissue damage, serious infections, and even death in animals. Although human infections are rare, they can occur in certain situations.
The first confirmed U.S. case this year was detected in a calf in South Texas in early June. Since then, additional cases have been identified across several counties, raising concerns about the parasite’s spread. Most reported cases have involved cattle, but infections have also been found in goats, sheep, dogs, and wildlife. Veterinary experts warn that early detection is essential because timely treatment can prevent serious health complications and reduce further transmission.
Texas plays a vital role in the U.S. livestock industry, making the outbreak an important issue for ranchers and agricultural businesses. A widespread infestation could affect animal welfare, increase veterinary costs, disrupt livestock movement, and create significant economic challenges for producers. Because the parasite can spread quickly among susceptible animals, continuous surveillance has become a top priority for state and federal authorities.
To control the outbreak, officials are using a proven biological control method that involves releasing sterile male screwworm flies into affected areas. These sterile flies mate with wild female flies, preventing successful reproduction and gradually reducing the parasite population over time. This strategy has successfully eliminated the pest from the United States in the past and remains one of the most effective methods available today.
Animal owners are encouraged to inspect livestock and pets regularly, especially if they have cuts, surgical wounds, or other skin injuries. Symptoms such as unusual wounds, foul smelling discharge, swelling, or signs of pain should be reported to a veterinarian immediately. Quick diagnosis and treatment can significantly improve recovery while helping authorities track and contain new infestations.
Federal and state agencies continue to update surveillance data as new cases are investigated. Officials stress that cooperation among ranchers, veterinarians, wildlife managers, and animal owners will play a key role in preventing the parasite from spreading further. With continued monitoring, rapid reporting, and effective control programs, experts hope to protect animal health and reduce the long-term impact of the outbreak on the livestock industry.