A troubling development has emerged in the realm of animal health in the United States, as officials have reported the resurgence of a dangerous parasite. For the first time in 60 years, Cochliomyia hominivorax, commonly known as the New World screwworm fly, has been detected in the country. This alarming finding was confirmed in a three-week-old calf located in Zavala County, Texas.
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On June 3, United States Secretary of Agriculture Brooke Rollins took to social media to announce the discovery. In her statement, she reported that the U.S. Department of Agriculture (USDA) and the Texas Animal Health Commission were swiftly mobilising to contain and eliminate the screwworm presence in the affected area. Rollins also mentioned that she had met with approximately 50 local cattle ranchers to discuss the implications of this alarming development.
The New World screwworm is a flesh-eating parasite notorious for laying its eggs in open wounds or body openings of warm-blooded mammals, including humans. According to the Centers for Disease Control and Prevention (CDC), this pest tends to exploit points of entry such as the eyes, ears, nose, mouth, or genital areas. Once the eggs hatch, they transform into maggots that burrow into the host’s flesh, potentially causing severe harm or death.
The USDA has previously underscored the detrimental impact of screwworm infestations, labelling them a “devastating pest.” With the capacity to inflict serious, often fatal injuries, the return of this parasite is a matter of grave concern. The agency noted that while the screwworm had been effectively eradicated from the United States in the 1960s, it has been gradually spreading northward from parts of South America through Central America and Mexico in recent years.
Historical records reveal that the United States had successfully eliminated the New World screwworm decades ago; however, the parasite has made a comeback. In a significant but isolated case, a human infection was reported in August 2025, linked to an individual’s return from El Salvador, raising concerns about the potential for the disease affecting humans as well as livestock.
The life cycle of the screwworm is particularly alarming. A single female fly can lay between 200 to 300 eggs at a time and can produce as many as 3,000 eggs during her lifespan of ten to 30 days. The larvae emerge and begin to consume the host’s living tissue, typically after seven days of feeding. To mitigate health risks, it is vital for individuals who suspect they may have been infected to seek urgent medical attention for the removal of any maggots present.
In addressing the latest outbreak, the USDA emphasised the importance of reporting any further cases to local authorities. They provide a dedicated hotline through USDA Wildlife Services for this purpose. Furthermore, officials are working with a strategy involving the release of sterile flies as a method of combatting this pest.
The recent identification of the New World screwworm in Texas speaks to a broader issue of the potential reintroduction of previously eradicated pests into America’s ecosystem. The USDA is committed to employing resources and expertise gained from past successes in combating the screwworm to tackle this challenge head-on.
As of the latest updates, no additional cases have been reported, but officials remain vigilant. The situation serves as a stark reminder of the ongoing efforts required to protect public health and agriculture in the face of evolving threats.
Moving forward, thorough monitoring and prompt responses will be critical in preventing the spread of the New World screwworm. The USDA has expressed confidence in their ability to manage the situation and to ensure the safety of animals and humans alike as they work to eradicate this menacing pest once more.