{"id":216953,"date":"2026-07-13T15:02:59","date_gmt":"2026-07-13T15:02:59","guid":{"rendered":"https:\/\/quixnet.net\/wpinstance\/experts-warn-of-ways-screwworm-could-spread-in-the-us-and-new-difficulties-in-keeping-it-at-bay-the-guardian\/"},"modified":"2026-07-13T15:02:59","modified_gmt":"2026-07-13T15:02:59","slug":"experts-warn-of-ways-screwworm-could-spread-in-the-us-and-new-difficulties-in-keeping-it-at-bay-the-guardian","status":"publish","type":"post","link":"https:\/\/quixnet.net\/wpinstance\/experts-warn-of-ways-screwworm-could-spread-in-the-us-and-new-difficulties-in-keeping-it-at-bay-the-guardian\/","title":{"rendered":"Experts warn of ways screwworm could spread in the US and new difficulties in keeping it at bay – The Guardian"},"content":{"rendered":"

Scientists worry that current eradication efforts won\u2019t be able to contain parasitic infestation pushing into US
When conservationists set up cameras in remote regions of Central American forests, they wanted to monitor illegal cattle movement, which can lead to deforestation<\/a>. But in recent months, they discovered another alarming development: wildlife rapidly infected with the new world screwworm.
It\u2019s a warning sign of how the fly could spread in the US \u2013 and it signals new difficulties in pushing it back south, a process that will probably take years, experts say.
\u201cWe got a really unique perspective throughout the beginning of the process,\u201d said Jeremy Radachowsky, director of the Mesoamerica and Caribbean program at the Wildlife Conservation Society, which recently released a study<\/a> on the phenomenon.
The cameras captured all types of wildlife \u2013 jaguar, puma, tapir, deer, white-lipped peccary, even porcupines \u2013 covered in the unmistakable wounds caused by the parasitic fly. Some of the mammals shared water sources with the cattle, which were moved across national borders without requisite health and safety checks. From there, the fly ripped through wildlife.
\u201cWe see infestations in the deepest parts of the interiors of the forest, so now it\u2019s become endemic in wildlife, far from the cattle infestations,\u201d Radachowsky said.
Screwworm has been detected<\/a> in 34 animals in the US \u2013 most in Texas, with one in New Mexico. So far, they have only been found in livestock and pets, with no wildlife detections in the US.
The US is now dropping 100 million sterile flies in the south-west and Mexico<\/a> \u2013 which may be enough to slow the northward movement of the parasitic fly, but will not be enough to eradicate it from the region. For that, they\u2019d need about 500 million sterile flies.
\u201cWhat we lack are sufficient flies in order to start pushing the population back south,\u201d said Phillip Kaufman, professor and department head of entomology at Texas A&M University.
Officials are now rushing to expand the capacity for breeding sterile flies. One facility opened in Mexico in late June, with another facility in Texas planned to open in late 2027. These flies are irradiated so that they cannot reproduce; when the males mate with females, the eggs are not fertilized and thus the population crashes.
There are new potential innovations for battling the screwworm on the horizon, like only raising sterile male flies (instead of male and female flies) or designing better bait traps to catch the wild flies. These methods could prove more effective, but they also take time to develop.
\u201cWe have to have things that work,\u201d Kaufman said. \u201cWe can\u2019t stop doing things we know work in order to try things that don\u2019t have any data to support. We are relying on science to solve this problem.\u201d
There are other potential solutions as well that would rely on stopping illicit activities.
Efforts have mainly focused on the screwworm itself, instead of the underlying cause of the rapid move north, Radachowsky said.
\u201cThey\u2019re either eradicating the fly, making a fly that can\u2019t reproduce or trying to trap the fly. What they\u2019re not doing is addressing the root cause of the cattle trafficking,\u201d he said. \u201cIf you\u2019re only using sterile fly technique and you have other factors that are moving beyond your efforts to blanket those areas with sterile flies, you\u2019re never going to have the capacity to clear huge areas.\u201d
The livestock industry, especially illegal cattle movement, has changed significantly since the flies were pushed out in 1966, Radachowsky argued.
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\u201cThere\u2019s this expectation and this simple argument that the sterile fly technique worked once, so it will work again,\u201d he said. \u201cBut the problem is in the 60s, when we first eradicated screwworm, we didn\u2019t have this high density of cattle like we do now. The human population and cattle population is just incredibly different from what it was back then, and the [illicit] cattle movements didn\u2019t exist before.\u201d
The screwworm got through the Dari\u00e9n Gap in 2022, working its way north until it hit Nicaragua. From there, \u201cit basically shot northward through Central America\u201d, moving thousands of kilometers in only four or five months \u2013 \u201cat the speed of a truck, and exactly along those illegal cattle-trafficking routes that we had already documented\u201d, Radachowsky said.
Illegally moving animals does seem like the primary driver for the return of the screwworm, Kaufman said.
\u201cThere\u2019s not a lot of wildlife that go on long-distance migrations\u201d in this region, he added. \u201cWhen you see it jump 50 or 100 miles, that wasn\u2019t an adult fly flying that far. They don\u2019t do that. It was people,\u201d he said, who were transporting livestock or pets.
For the US, the biggest alarm bells started sounding about 18 months ago when the screwworm re-entered Mexico. Officials and experts scrambled to understand how to push it back.
\u201cMexico had not had the pest in probably 35 years or so, so all the people who knew what to do have either passed or long retired,\u201d Kaufman said.
In the US, the screwworm is considered a foreign animal disease pest, so there are restrictions on how scientists may study it. \u201cWe were not permitted to have the fly in research facilities in the US for the last 50 years, because it\u2019s such a dangerous organism,\u201d Kaufman said. Scientists don\u2019t know which odors attract the fly, for instance, in order to create effective bait traps. That\u2019s the kind of work being started now through grants<\/a> from the US Department of Agriculture.
Conservationists are \u201cextremely worried\u201d that \u201cbasically the door is wide open for infectious disease transmission\u201d, Radachowsky said \u2013 not just the screwworm but also other livestock-borne illnesses, such tuberculosis, brucellosis, hoof and mouth disease, and bird flu.
\u201cIt frightens me that we\u2019re not learning the main lesson here,\u201d Radachowsky said. More disease monitoring is also needed to examine wildlife populations in the Americas<\/a>, he added. \u201cThere\u2019s a lot of wildlife that\u2019s probably disappearing without anybody ever having any evidence of it. It\u2019s guaranteed that we\u2019re just scratching the surface.\u201d<\/p>\n

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Scientists worry that current eradication efforts won\u2019t be able to contain parasitic infestation pushing into USWhen conservationists set up cameras in remote regions of Central American forests, they wanted to monitor illegal cattle movement, which can lead to deforestation. But in recent months, they discovered another alarming development: wildlife rapidly infected with the new world […]<\/p>\n","protected":false},"author":1,"featured_media":216954,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[10],"tags":[],"class_list":["post-216953","post","type-post","status-publish","format-standard","has-post-thumbnail","category-world","entry"],"_links":{"self":[{"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/posts\/216953","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/comments?post=216953"}],"version-history":[{"count":0,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/posts\/216953\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/media\/216954"}],"wp:attachment":[{"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/media?parent=216953"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/categories?post=216953"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/quixnet.net\/wpinstance\/wp-json\/wp\/v2\/tags?post=216953"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}