First U.S. Human Screwworm Case Sparks Concern

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. 

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