Full Breakdown
First Human Case of New World Screwworm Confirmed in the U.S.
8/31/2025, 12:40:57 PM
Overview of the Incident
On August 4, 2025, the Centers for Disease Control and Prevention (CDC) confirmed the first human case of New World screwworm (NWS) myiasis in the United States. The patient, a Maryland resident, had recently traveled to El Salvador, where active cases of the parasite are reported. The Maryland Department of Health stated that the individual has since recovered, and there is no indication of transmission to other people or animals.
Background on New World Screwworm
The New World screwworm, scientifically known as Cochliomyia hominivorax, is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals, including livestock and, in rare cases, humans. The larvae can cause severe tissue damage and even death if left untreated. Historically, screwworms were eradicated in the U.S. by the 1960s, but recent outbreaks in Central America and Mexico have raised concerns about their reintroduction.
Current Outbreak and Surveillance Efforts
Since a significant outbreak was declared in Central America in July 2023, the Commission for the Eradication and Prevention of Screwworm has tracked over 49,500 cases, with 161 confirmed in humans. In response to the Maryland case, the U.S. Department of Agriculture (USDA) initiated targeted surveillance within a 20-mile radius of the affected area, which includes parts of Maryland, Virginia, and Washington, D.C. As of August 26, all trap results have been negative for screwworms.
Economic Implications and Industry Response
The livestock industry is closely monitoring the situation, as an outbreak could have severe economic consequences. Estimates suggest that an infestation could cost Texas, the largest cattle-producing state, approximately $1.8 billion. The National Cattlemen’s Beef Association (NCBA) has stated that there is currently no elevated risk to the livestock industry, while R-CALF USA has expressed concerns over the government's communication regarding the case, suggesting that information was selectively shared with industry insiders before the public announcement.
Criticism and Calls for Transparency
R-CALF USA has called for an investigation into the handling of the case, criticizing what they perceive as a lack of transparency from government agencies. They argue that the selective dissemination of information undermines trust and could jeopardize the health of livestock. The organization has requested the establishment of a New World Screwworm task force to ensure better communication and resource allocation in preventing future outbreaks.
Official Statements
Health officials have emphasized that the risk to public health from this isolated case remains very low. Andrew Nixon, a spokesperson for the Department of Health and Human Services, stated, “The risk to U.S. public health from this case was very low.” Meanwhile, Texas A&M University entomology professor Phillip Kaufman noted, “It is certainly a solvable problem. We are not without answers.”
What's Next
As the USDA continues its surveillance efforts, the agency is also preparing for potential scenarios should the screwworm spread further into the U.S. The situation remains under close observation, with ongoing collaboration between federal and state agencies to mitigate risks associated with the parasite.
