The threat many cattle producers feared has now become reality.
The U.S. Department of Agriculture has confirmed the first case of New World screwworm inside the United States after larvae were discovered in a 3 week old calf in Zavala County, Texas. The infestation was found in the calf’s navel area, a common entry point for the destructive parasite.
Federal and state animal health officials have launched an aggressive response aimed at preventing the pest from spreading deeper into cattle country.
New World screwworm is not a disease. It is a flesh eating fly whose larvae burrow into living tissue. Unlike common maggots that feed on dead tissue, screwworm larvae attack healthy flesh, creating deep wounds that can rapidly become life-threatening if left untreated.
The pest can infest cattle, horses, sheep, goats, wildlife, pets and, in rare cases, people.
USDA officials say no additional cases have been confirmed at this time, but emergency response efforts are already underway. A 20 kilometer control zone has been established around the detection site, with movement restrictions, surveillance efforts and increased trapping operations now in place.
The agency is also accelerating the release of sterile screwworm flies, a proven eradication strategy that helped eliminate the pest from the United States decades ago. Ground release operations are being added to aerial releases already occurring along the border region.
USDA Under Secretary for Marketing and Regulatory Programs Dudley Hoskins said protecting the livestock industry remains a top priority and noted that federal, state and industry partners have spent months preparing for the possibility of a U.S. detection.
For ranchers and livestock owners, vigilance is now critical.
Producers are being urged to inspect animals regularly for wounds that appear larger than expected, fail to heal, or show signs of drainage. Newborn calves deserve special attention, particularly around the navel area. Officials also recommend checking around the ears, nose, eyes and reproductive areas where flies may deposit eggs.
Animals suffering from screwworm infestations often appear restless, irritated, depressed or reluctant to eat. In severe cases, infestations can spread rapidly as hundreds of larvae feed within a wound.
Wildlife officials are also increasing monitoring efforts because deer, feral hogs and other wild animals can help spread the pest across large areas.
USDA emphasized that the nation’s food supply remains safe. Screwworm does not infest meat products, and animals entering federally inspected processing facilities undergo inspection procedures designed to identify signs of infestation.
The economic stakes are significant. Beyond animal suffering and death losses, a widespread outbreak could impact cattle movement, livestock marketing, interstate commerce and international trade.
The United States successfully eradicated New World screwworm in the 1960s through a massive sterile fly program. Animal health officials believe the same science can stop this outbreak, but they stress that early detection and producer awareness will be critical.
Any producer who suspects a screwworm infestation should immediately contact their veterinarian, state animal health official or USDA animal health authorities.
For now, officials are treating the Texas detection as an isolated case. But for cattle producers across the country, it serves as a reminder that one of the livestock industry’s most dangerous parasites is once again on American soil.
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