疫情爆發多年後，美國如何暴露在噬肉螺旋蛆蟲威脅之下

墨西哥城／華盛頓，11月9日（路透社）——數十年來，飛機投放數十億隻由工廠繁殖的不孕蠅，以阻止噬肉的新世界螺旋蛆蟲侵入北美牛群。這種方法能控制害蟲，是因為不孕雄蠅會與野生雌蠅交配，使其產下的卵無法孵化。MEXICO CITY/WASHINGTON, Nov 9 (Reuters) - For decades, planes dropped billions of factory-bred sterile flies to keep the flesh-eating New World screwworm out of North America’s cattle. That controls the pest because sterile males mate with wild females – whose eggs then fail to hatch.

但這項策略只有在不孕蠅供應從不短缺時才有效。But the strategy works only if the supply of flies never runs short.

2023年初，這種寄生蟲突破巴拿馬的不孕蠅屏障時，該區域沒有足夠能力將其圍堵。路透社訪問美國、墨西哥與巴拿馬15名現任及前任官員與專家後得知，在疫情爆發超過3年、寄生蟲已肆虐墨西哥並進入美國之後，擴大不孕蠅族群的努力仍然落後。When the parasite broke through a barrier of sterile flies in Panama in early 2023, the region lacked the capacity to contain it. Efforts to scale up the fly population still lag more than three years into the outbreak, after the parasite ripped through Mexico and into the United States, according to Reuters interviews with 15 current and former officials and experts in the US, Mexico and Panama.

由於不孕蠅不足，美國總統唐納・川普（Donald Trump）政府自2025年5月起暫停自墨西哥進口牛隻超過15個月，衝擊數十億美元規模的貿易。隨著邊境今年開始重新開放，美國牛隻已確認數十起病例。Short on flies, the administration of US President Donald Trump closed the border with Mexico to cattle imports for more than 15 months starting in May 2025, disrupting a multibillion-dollar trade. As the border began to reopen this year, dozens of cases were confirmed in US cattle.

根據美國與墨西哥政府資料，墨西哥與巴拿馬目前每週合計生產約1億5000萬隻不孕蠅。Mexico and Panama currently produce a total of about 150 million sterile flies a week, according to US and Mexican government data.

這不到1960年代美國根除螺旋蛆蟲行動每週所需5億隻的三分之一；專家也建議以每週5億隻作為基準，才能把害蟲控制在巴拿馬以南。美國沒有自己的不孕蠅工廠，德州一座興建中的工廠預計要到2027年春季才會開始生產。That’s less than a third of the 500 million per week it took during a 1960s campaign that eradicated the screwworm in the US – and that experts recommend as the benchmark to keep the pest contained to south of Panama. The US has no sterile-fly plant of its own, and one under construction in Texas isn’t expected to start production until spring 2027.

與此同時，寄生蟲已擴散到墨西哥大部分地區，確診約5萬1000例。美國迄今通報120例。Meanwhile, the parasite has spread across most of Mexico, with about 51,000 confirmed cases. The United States has recorded 120 cases to date.

德州農工大學昆蟲學家索尼婭・斯威格（Sonja Swiger）說：「我們沒有足夠的不孕蠅。他們一開始就知道這點。」"We don't have enough flies,” said Sonja Swiger, an entomologist at Texas A&M University. “They knew that right away."

現任與前任政府官員告訴路透社，在蟲害蔓延的數個階段，增加不孕蠅生產的努力受到政治交接、經費延宕、官僚障礙及美墨緊張升高所阻礙。Efforts to make more flies at several stages of the infestation have been hampered by political transitions, funding delays, bureaucratic hurdles and rising US-Mexico tensions, current and former government officials told Reuters.

美國農業部（USDA）發言人南希・麥克尼夫（Nancy McNiff）以電子郵件回覆路透社時表示，該機構「已緊急行動，並採取每一項實際可行的途徑，以盡快將更多不孕蠅投入野外」。USDA spokesperson Nancy McNiff said in emailed responses to Reuters that the agency has “acted urgently and pursued every practical avenue to get more sterile flies into the field as quickly as possible.”

墨西哥總統克勞蒂亞・薛恩寶（Claudia Sheinbaum）、墨西哥農業部、巴拿馬—美國根除與預防螺旋蛆蟲委員會（COPEG）以及巴拿馬政府的發言人，均未回應採訪請求。Spokespeople for Mexican President Claudia Sheinbaum, Mexico’s agriculture ministry, the Panama-United States Commission for the Eradication and Prevention of Screwworm (COPEG) and Panama’s government did not respond to requests for comment.

巴拿馬拉警報ALARM IN PANAMA

螺旋蛆蟲幼蟲會撕裂活體組織，未治療的動物可能因此死亡。一隻蠅最多可產下3000顆卵。Screwworm larvae tear through living tissue and can kill untreated animals. A single fly can lay up to 3,000 eggs.

投放數十億隻工廠製造的不孕蠅，使美國在1966年根除螺旋蛆蟲，並在2017年控制佛羅里達州的一波疫情。Releases of billions of factory-made sterile flies eradicated screwworm in the US in 1966 and contained a flare-up in Florida in 2017.

2023年2月下旬，巴拿馬達連省官員在一片長期作為北美最後防線的叢林內，面對約800起螺旋蛆蟲病例。In late February 2023, officials in Panama's Darien province confronted about 800 cases of screwworm inside the jungle that had long served as North America's last line of defense.

維持這道屏障是COPEG的職責；這個美國與巴拿馬共同組成的組織，其大部分經費來自美國。一名參與因應行動的巴拿馬官員表示，COPEG在2023年4月決定將不孕蠅產量從每週2000萬隻提高到1億隻。Maintaining that barrier is the job of COPEG, the US-Panamanian organization that gets most of its funding from the US. In April 2023, it decided to increase sterile-fly production to 100 million a week from 20 million a week, said a Panamanian official involved in the response.

到2023年7月，巴拿馬宣布螺旋蛆蟲擴散進入緊急狀態，擴大不孕蠅投放、加強家畜管制並強化監測。By July 2023, Panama declared the spread of screwworm an emergency, expanding sterile-fly releases, tightening livestock controls and intensifying surveillance.

2023年12月，美國前總統喬・拜登（Joe Biden）政府宣布，將為巴拿馬及其他地區的螺旋蛆蟲偵測與不孕蠅生產追加近1億1000萬美元經費。In December 2023, the administration of former US President Joe Biden announced nearly $110 million in additional funding for screwworm detection and sterile-fly production in Panama and elsewhere.

這名巴拿馬官員表示，到2024年11月，也就是擴產開始19個月後，巴拿馬工廠每週產量達到1億隻不孕蠅。In November 2024, 19 months into the expansion, Panama’s plant reached 100 million flies a week, according to the Panamanian official.

同月，墨西哥在與瓜地馬拉接壤的南部恰帕斯州確認首批病例，並開始投放不孕蠅。That month Mexico confirmed its first cases in Chiapas, a southern state bordering Guatemala, and began releases.

這名巴拿馬官員告訴路透社，當時主管機關已經知道每週1億隻不孕蠅並不夠。By then, the authorities knew that 100 million sterile flies a week was not enough, the Panamanian official told Reuters.

墨西哥的缺口GAPS IN MEXICO

美國與墨西哥的選舉拖慢了因應速度。Elections in the United States and Mexico slowed the response.

一名熟悉因應行動的墨西哥官員表示，2024年9月，總統安德烈斯・曼努埃爾・羅培茲・歐布拉多（Andres Manuel Lopez Obrador）政府準備卸任之際，即將離任的官員警告接任者，螺旋蛆蟲疫情需要立即關注。In September 2024, as President Andres Manuel Lopez Obrador’s administration prepared to leave office, outgoing officials warned their successors that the screwworm epidemic needed immediate attention, a Mexican official familiar with the response said.

早期規劃著重於改造恰帕斯州梅塔帕一座既有果實蠅工廠，而不是興建新廠。Early planning centered on converting an existing fruit-fly plant in Metapa, Chiapas, rather than building a new plant.

這名官員表示，由於新政府需釐清經費並為總統克勞蒂亞・薛恩寶準備提案，政權交接使相關工作延宕3到4個月。The handover delayed the effort by three to four months, the official said, as the new government sorted out funding and prepared a proposal for President Claudia Sheinbaum.

2025年5月，川普政府宣布為梅塔帕計畫提供2100萬美元經費。美國與墨西哥官員表示，該工廠最終每週可生產6000萬至1億隻不孕蠅。In May 2025, the Trump administration announced $21 million in funding for the Metapa project. US and Mexican officials said the plant could eventually produce 60 million to 100 million sterile flies a week.

COPEG的不孕蠅投放作業在2026年2月轉往德州—墨西哥邊境。Sterile-fly drops from COPEG shifted to the Texas-Mexico border in February 2026.

根據這名墨西哥政府官員，薛恩寶敦促各機構加速推動墨西哥工廠計畫，希望在4月啟用。最終，該設施於6月27日揭幕，距離墨西哥確認首起螺旋蛆蟲病例已超過18個月。Sheinbaum pushed agencies to accelerate Mexico’s plant project, seeking an April launch, according to the Mexican government official. In the end, the facility was inaugurated on June 27 – more than 18 months after the country confirmed its first screwworm case.

到那時，寄生蟲已擴散至27個州，並抵達墨西哥北部主要養牛區科阿韋拉州與杜蘭戈州，距離南部邊境數百英里。By then, the parasite had spread across 27 states, reaching major cattle-producing areas of Coahuila and Durango in northern Mexico, hundreds of miles from the southern border.

德州的一座工廠A PLANT IN TEXAS

美國首例病例於6月3日確認。但美國仍沒有自己的生產設施。The first US case was confirmed on June 3. But the US still had no production facility of its own.

一名前拜登政府官員表示，美國農業部已在2024年11月開始討論設施設置，現場人員也在同月與12月就選址與德州養牛業團體會面。USDA had begun discussing a facility in November 2024, and field staff met with Texas cattle industry groups about locations that month and in December, according to a former Biden official.

2025年6月，農業部長布魯克・羅林斯（Brooke Rollins）表示，美國農業部正在考慮德州愛丁堡的摩爾空軍基地；該基地有一座已停用的蠅類工廠，曾是1960年代行動成功的關鍵。In June 2025, Agriculture Secretary Brooke Rollins said the USDA was considering Moore Air Force Base in Edinburg, Texas, home to a retired fly plant that had been key to the success of the 1960s campaign.

根據美國政府支出資料庫中公開可查的合約紀錄，川普政府今年3月將一份6億1000萬美元合約授予M.A.莫滕森公司（M.A. Mortenson），以興建該設施。This March, the Trump administration awarded a $610 million contract to M.A. Mortenson to construct the facility, according to publicly available records of the contract through a US government spending database.

發言人麥克尼夫表示，美國農業部起初認為該計畫可能需要最多5年。The USDA initially believed the project could take up to five years, spokesperson McNiff said.

政府官員施壓要求加快進度。根據支出紀錄，美國農業部限制營建標案的投標對象，主張公開招標可能使這項時間敏感的計畫延宕。Administration officials pressed to move faster. USDA limited bids on construction, arguing that open bidding could delay a time-sensitive project, according to the spending records.

在9月一場德州農工大學系統校董會會議上，羅林斯表示，國防部長皮特・赫格塞斯（Pete Hegseth）已將該計畫移至陸軍工兵團優先清單首位，把時程縮短至約18個月，也就是2027年秋季。At a September meeting of the Texas A&M Board of Regents, Rollins said Defense Secretary Pete Hegseth had moved the project to the top of the Army Corps’ priority list, cutting the timeline to about 18 months, or fall 2027.

羅林斯負責螺旋蛆蟲事務的顧問、同時也是校董會成員的約翰・貝林格（John Bellinger）表示，他推動時程進一步提前。貝林格對校董會說：「只多花2億5000萬美元，我們就把它提前到明年4月1日。」這使時程再縮短約6個月。John Bellinger, Rollins’ advisor on screwworm and a member of the board, said he pushed to move even faster. "For only $250 million more, we got it moved to April 1 of next year," Bellinger told the regents, further shortening the timeline by about six months.

莫滕森公司發言人卡麥隆・史奈德（Cameron Snyder）在電子郵件中表示，該公司致力於與美國農業部及陸軍工兵團合作，迅速交付這座工廠。Mortenson spokesperson Cameron Snyder said in an email that the company is committed to working with the USDA and the Army Corps to deliver the plant quickly.

在該工廠啟用之前，美國仍仰賴其他地方生產的不孕蠅，也就是巴拿馬與墨西哥梅塔帕工廠合計每週約1億5000萬隻的產量。Until the plant opens, the United States remains reliant on sterile flies produced elsewhere, roughly 150 million a week combined from the plants in Panama and Metapa, Mexico.

雖然恰帕斯州仍是墨西哥受創最嚴重的州，約有8200起確認感染病例，但美國農業部表示，巴拿馬與墨西哥生產的所有不孕蠅，目前都投放在墨西哥北部與美國。Although Chiapas remains Mexico’s hardest-hit state, with about 8,200 confirmed infestations, USDA said all sterile flies produced in Panama and Mexico are currently being released in northern Mexico and the US.

這項策略目標是在寄生蟲繼續北移前先加以阻止，之後再往南回推；這使墨西哥與中美洲大部分地區只能依賴監測與治療，而非根除。The strategy aims to stop the parasite’s northward advance before working back south, leaving much of Mexico and Central America reliant on surveillance and treatment, rather than eradication.

斯威格說，即使在病例已受到壓制的地區，防護仍取決於不孕蠅能否一週又一週持續送達。Even where cases have been suppressed, protection depends on sterile flies arriving week after week, Swiger said.

一些專家估計，可能需要長達10年才能把螺旋蛆蟲感染範圍推回巴拿馬。這意味著，北美對這種害蟲的防線依賴一條生物供應鏈；而疫情爆發超過3年後，這條供應鏈仍只生產所需不孕蠅的一小部分。Some experts estimate it could take as long as a decade to push the screwworm infestation back to Panama. That leaves North America’s defense against the pest dependent on a biological supply chain that – more than three years into the outbreak – still produces only a fraction of the needed sterile flies.

（墨西哥城Cassandra Garrison、Adriana Barrera與華盛頓Leah Douglas報導；Emily Schmall與Suzanne Goldenberg編輯）(Reporting by Cassandra Garrison and Adriana Barrera in Mexico City and Leah Douglas in Washington. Editing by Emily Schmall and Suzanne Goldenberg)