The first human case of travel-associated New World screwworm in the U.S. raises concerns over biosecurity and economic impact.
Story Overview
- The U.S. reports its first human case of travel-associated New World screwworm.
- The case originates from a traveler returning from an outbreak-affected country.
- Heightened vigilance is in place to protect livestock and biosecurity.
- Federal agencies are implementing measures to prevent screwworm establishment.
First Human Case Detected
On August 24, 2025, the U.S. Department of Health and Human Services announced the first U.S. human case of travel-associated New World screwworm (NWS). This parasitic infestation, caused by fly larvae, was confirmed by the CDC on August 4, 2025. The case involves a traveler who recently returned from El Salvador, an area affected by an outbreak. Despite the low risk to the general public, there is significant concern for livestock and biosecurity.
Impact on Livestock and Biosecurity
The New World screwworm poses a serious threat to the U.S. livestock industry, which is highly sensitive to such pests. The larvae infest warm-blooded animals, causing severe economic losses and animal suffering. In response, the USDA has expanded surveillance and border controls to prevent the pest’s reintroduction. The case highlights the ongoing need for vigilance, given the recent northward spread of NWS from Central America.
Federal and state agencies, along with the livestock industry, are coordinating efforts to maintain biosecurity and protect public and animal health. There is an increased focus on travelers from outbreak-affected countries, who may unknowingly introduce the pest.
Government and Industry Response
The USDA has announced sweeping plans to prevent the establishment of NWS, emphasizing collaboration with state and private sectors. Surveillance and border controls have been intensified, and there is a push for transparency and rapid response to any potential outbreaks. Although no animal cases have been confirmed in the U.S. in 2025, the livestock industry remains on high alert.
The CDC and public health officials have stated that the risk of widespread transmission is low, but early detection and rapid response are crucial. The case underscores the importance of preparedness and the need for ongoing research into prevention and treatment options.
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