The United States Department of Agriculture has confirmed the first instance of New World screwworm in a domestic animal since 1966, following the detection of the parasite in a calf in Texas.

美國農業部已確認自 1966 年以來，國內首次在家畜身上發現新世界螺旋蠅，該寄生蟲是在德州的一頭小牛身上被偵測到。

The infestation was identified in a three-week-old calf in La Pryor, Texas, approximately 50 kilometers from the Mexican border. The larvae were located in the umbilical cord, suggesting a locally acquired infestation. In response, a 20-kilometer quarantine zone has been established to prohibit animal movement. The specimen has been transported to the National Veterinary Services Laboratories in Ames, Iowa, for further analysis.

此次感染是在德州 La Pryor 一頭三週大的小牛身上發現的，該地距離墨西哥邊境約 50 公里。幼蟲位於臍帶中，顯示為本地感染。對此，當局已建立一個 20 公里的隔離區以禁止動物移動。樣本已被運送到愛荷華州 Ames 的國家獸醫服務實驗室進行進一步分析。

Historically, the New World screwworm was eradicated from the U.S. in 1966 via the systematic release of sterile male flies. However, the parasite has recently re-emerged across Central America and Mexico. Experts hypothesize that this resurgence may be attributed to the disruption of sterile-fly programs during the COVID-19 pandemic, augmented by favorable climatic conditions and increased transborder movement of livestock and personnel. Mexico reported a 53 percent increase in animal cases between mid-July and mid-August 2025.

歷史上，美國在 1966 年透過系統性釋放不孕雄飛，將新世界螺旋蠅根除。然而，該寄生蟲近期在中美洲和墨西哥重新出現。專家假設，此種復甦可能歸因於 COVID-19 疫情期間不孕飛計畫的中斷，加上有利的氣候條件以及跨境牲畜與人員流動的增加。墨西哥報告指出，2025 年 7 月中旬至 8 月中旬，動物病例增加了 53%。

From a biological perspective, the parasite involves female flies depositing eggs in the open wounds of warm-blooded hosts. The resulting larvae consume living tissue, leading to progressive necrosis and potential mortality if untreated. While human infection is rare, the U.S. Department of Health and Human Services reported the first domestic human case in August 2024, linked to travel from El Salvador. Dr. Timothy Goldsmith of the University of Minnesota noted that individuals experiencing homelessness are disproportionately vulnerable due to limited access to hygiene and medical care.

從生物學角度來看，該寄生蟲是由雌飛將卵產在溫血宿主的開放性傷口中。產出的幼蟲會吞食活組織，導致漸進性壞死，若不治療可能導致死亡。雖然人類感染罕見，但美國衛生與公共服務部報告指出，2024 年 8 月出現首例國內人類病例，與前往薩爾瓦多旅行有關。明尼蘇達大學的 Timothy Goldsmith 博士指出，由於衛生與醫療資源有限，無家可歸者更容易受到影響。

Economically, the re-establishment of the parasite poses a significant threat to the livestock industry. The USDA estimates potential losses to the Texas economy at $1.8 billion. Furthermore, the U.S. government has suspended cattle imports from Mexico for the past year to mitigate risk. This suspension, compounded by drought-induced herd reductions, has constrained the beef supply and contributed to record-high consumer prices. Current biosecurity measures include stringent health certification for pets and livestock entering from affected regions.

在經濟方面，該寄生蟲的重新建立對畜牧業構成了重大威脅。美國農業部估計德州經濟的潛在損失達 18 億美元。此外，美國政府在過去一年中暫停從墨西哥進口牛隻以降低風險。此項暫停措施加上乾旱導致的牛群減少，限制了牛肉供應，並導致消費者價格達到歷史高點。目前的生物安全措施包括對從受影響地區進入的寵物和牲畜實施嚴格的健康證明認證。

The situation remains under containment, with federal authorities focusing on vigilance, isolation, and the potential implementation of sterile-male release programs to prevent wider domestic establishment.

情況目前仍在控制之中，聯邦當局正集中精力進行監測、隔離，並考慮實施不孕雄飛釋放計畫，以防止國內更大範圍的擴散。