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First U.S. Human Screwworm Case Sparks Concern

First U.S. Human Screwworm Case Sparks Concern
Sep 02, 2025
By Farms.com

Transparency questioned after delayed confirmation

The first human case of travel-associated New World screwworm in the United States has been confirmed, with officials reporting the patient has fully recovered. The Maryland Department of Health confirmed there was no sign of spread to other people or animals. 

The Centers for Disease Control and Prevention (CDC) verified the case on August 4 in a person who had recently returned from El Salvador. However, the public announcement came nearly three weeks later, raising questions about transparency and trust in public agencies. 

Industry leaders criticized the delay. Neal Wilkins, CEO of the East Foundation, stated that withholding information undermines confidence among producers and wildlife managers. Similarly, Bill Bullard, CEO of R-CALF USA, argued that failing to promptly share the case details with all producers weakens the system that protects U.S. livestock. 

The USDA has not addressed questions about its communication with the CDC. Officials did not mention the human case when announcing a $750 million investment in a Texas facility to produce sterile flies as part of ongoing screwworm control efforts. 

New World screwworms are parasitic flies that lay eggs in wounds of warm-blooded animals. Their larvae burrow into tissue, causing severe damage and, if untreated, death. While the risk to the general public is considered very low, the threat to livestock is significant. The parasite can kill cattle within ten days if not managed. 

Earlier this summer, detections in Mexico prompted U.S. restrictions on livestock imports. Even a single human case is enough to raise alarm within the agricultural community, given the parasite’s history of devastation. 

Photo Credit: gettyimages-minchen-liang-eyeem


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Assessing Welfare Resources During Late Finish - Dr. Anna Johnson & Emma Coursey

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In this episode of The Swine Nutrition Blackbelt Podcast, Dr. Anna Johnson from Iowa State University and Emma Coursey from the University of Illinois discuss research evaluating welfare resources during the late finishing stage on commercial swine farms. They explain how feeder management, water use, space allocation, and pig health influence welfare outcomes and practical on-farm management. Listen now on all major platforms!

"Small resource issues can become larger welfare problems when multiple stressors interact across finishing barns."

Meet the guests: Dr. Anna Johnson / anna-johnson-05028a14 is the Morrill Professor of Animal Behavior and Welfare at Iowa State University. She earned her Ph.D. in Animal Sciences from Texas Tech University and completed her master's degree in Applied Animal Behaviour and Welfare at the University of Edinburgh. Her research focuses on practical solutions that improve farm animal welfare, including sow productive lifetime, animal-human interaction, environmental enrichment, and Precision Livestock Farming.

Emma Coursey / emma-coursey-183810241 is pursuing a Doctor of Veterinary Medicine degree at the University of Illinois College of Veterinary Medicine after earning a bachelor's degree in Animal Science from Iowa State University. Her academic interests include swine health, production, and animal welfare, with research experience evaluating welfare resources in commercial finishing pigs.