Texas health officials warn of New World Screwworm after confirmed case in Zavala County

June 5, 2026 - 13:43

Texas health authorities are urging livestock owners and the public to take precautions after a case of New World Screwworm was confirmed in Zavala County. The discovery, made in a calf, marks a significant concern for animal health across the region. The parasitic fly larvae, known for infesting open wounds in warm-blooded animals, can cause severe tissue damage and even death if left untreated.

State officials emphasized that while the primary threat is to livestock, pets, and wildlife, the infection can also occur in humans, though it is rare. The New World Screwworm lays eggs on the edges of wounds or natural body openings. Once hatched, the maggots burrow into living tissue, feeding on the host. This differs from common blowflies, which typically target dead flesh.

Authorities are advising ranchers to inspect their animals regularly for any signs of infestation, such as irritated wounds or the presence of fly larvae. They also recommend treating all wounds promptly and reporting any suspicious cases to the Texas Animal Health Commission. The U.S. Department of Agriculture has been working to eradicate the pest from the country, but occasional outbreaks still occur, often linked to movement of animals from affected areas in Mexico and Central America. Residents are reminded to practice good wound care for both animals and themselves to prevent the spread of this dangerous pest.