Texas Governor Greg Abbott declared a state of disaster after a second case of New World screwworm was confirmed on a ranch in Zavala County, approximately 5.6 miles from the first infestation. The discovery prompted Canada to impose a temporary ban on livestock imports from Texas, specifically targeting cattle and horses that have been in the state witthin the past 21 days. The situation, described by officials as an “imminent threat” to the livestock industry, wildlife, and even humans, follows months of warnings from Texas Agriculture Commissioner Sid Miller and Governor Abbott.

5.6 miles and a second calf:Zavala County becomes ground zero

The second case, announced by the U.S. Department of Agriculture on Friday, was found in a calf on a ranch near the Texas-Mexico border , just 5.6 miles from the site of the first case earlier in the week. According to the source article, this proximity has heightened fears that the parasitic fly is establishing a foothold in the region. governor Abbott’s disaster declaration authorizes the use of all available state resources and the reassignment of personnel to accelerate the movement of sterile flies and support construction of a new sterile screwworm production facility in Edinburg. “We have eradicated this pest before, and we will do it again,” Abbott stated, according to the report.

Canada's 21-day ban: the border closes to Texas livestock

The Canadian Food Inspection Agency announced the temporary import ban on the same day as the second case was confirmed. As the source notes, the restriction applies to cattle and horses that have been located in Texas within the past 21 days, reflecting international concern about the parasite’s ability to cross borders . This swift move underscores the economic stakes: the screwworm larvae burrow into living flesh of warm-blooded animals, causing rapidly expanding wounds that can be fatal if untreated. The ban highlights how cross-border coordination is both essential and fragile in managing such outbreaks.

Commissioner Miller's SWASS push: a bait-based strategy vs. sterile flies

Texas Agriculture Commissioner Sid Miller has been critical of the USDA’s primary strategy, which relies on releasing sterile male flies to suppress the screwworm population. The source article reports that Miller argues this passive approach has failed, pointing to the screwworm’s advance of over 1,100 miles from southern Mexico into Texas despite billions of sterile flies being dispersed. He advocates for the Screwworm Adult Suppression System (SWASS), a bait-based technology developed by USDA scientists and used successfully during the last major U.S. outbreak in the 1970s. According to the source, Miller contends SWASS is no longer in use because the USDA deemed it environmentally insensitive. With the parasite now confirmed in Texas, Miller stresses the consequences of that decision are evident. He also notes that modern antiparasitic medications, unavailable during the 1970s, offer an additional tool if used under veterinary guidance.

A 1975 victory, a mild winter, and a 1,100-mile creep north

The New World screwworm was successfully eradicated from the United States in 1975 after a massive campaign that included SWASS. But the source reports that warnings had been issued for months: Commissioner Miller noted that swarms of screwworm flies were detected approximately 187 miles south of the Rio Grande even during winter, a deviation attributed to a mild winter. “If they’re active in the middle of winter,look out when spring or early summer gets here,” Miller warned in February. That prediction has now materialized. The current outbreak raises questions about how climate conditions and shifts in insect behavior may be complicating old eradication playbooks.

What remains unanswered

The source does not clarify whether the USDA plans to reconsider its stance on SWASS in light of the confirmed U.S. infestation. it also leaves open the question of how many more undetected cases may exist, since screwworm infestations can be missed until animals show visible wounds. Additionally, the report focuses on livestock impacts but provides limited detail on potential risks to wildlife and humans, though the parasite can infect both.