USDA animal health officials have reported the first animal case of gusano barrenador in the United States, finding larvae in the umbilical area of a 3-week-old calf during an inspection in Zavala County, Texas. It is the only registered U.S. case so far.
The finding matters because the parasite can strike cattle, pigs, dogs, cats, wildlife and humans, and it can cause wounds to worsen quickly. The fly behind it, Cochliomyia hominivorax, lays eggs in open wounds or natural body openings; after hatching, the larvae feed on living tissue, digging tunnels, deepening lesions and causing intense pain, secondary infections and serious damage if treatment comes too late.
That is why the Texas detection is being treated as more than a local veterinary problem. U.S. authorities said analyses of the pest indicated it would reach the southern United States, and the case in Zavala County arrived after the parasite had already moved north through Latin America, first emerging in July 2023 on the Panama-Costa Rica border and later reaching Chiapas in southern Mexico in November 2024.
The calf’s discovery also leaves a narrow but important gap: officials did not say how the animal was exposed or whether more infections have been found since the first inspection. Texas authorities and the USDA said they would carry out containment under the Worm Response Manual, but the report did not spell out the outcome of that response.
For ranchers and pet owners, the warning is immediate. The USDA asked residents to check animals for wounds that ooze or enlarge, signs of discomfort and worms in body openings such as the nose, ears, genitals or, in newborn animals, the umbilicus. Anyone who suspects an infection is being told to contact state animal health authorities or the USDA area veterinarian at once.
