The livestock sector across North America went into high alert following significant updates regarding the domestic spread of the flesh-eating New World Screwworm (Cochliomyia hominivorax).
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Second U.S. Detection Confirmed: The USDA’s Animal and Plant Health Inspection Service (APHIS) officially confirmed a second detection of the New World screwworm. The infestation was identified in a one-month-old calf in Zavala County, Texas, roughly 5.6 miles away from the initial location.
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The Eradication Strike: In response, USDA initiated aerial dispersal operations, releasing 2 million sterile screwworms twice a week directly over the infested corridor to disrupt the pest’s reproductive cycle. An additional 4 million sterile flies per week are being shipped to Texas to reinforce a 20-km quarantine zone.
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Canada Imposes Aggressive Border Blocks: The Canadian Food Inspection Agency (CFIA) issued an emergency temporary restriction halting all livestock entries from Texas. Any warm-blooded animals, including horses, that originated from or transited through Texas within 21 days prior to border arrival will be rejected at the Canada-U.S. border to protect domestic cattle networks.
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Tennessee Passes Emergency Movement Orders: State Veterinarian Samantha Beaty instituted a temporary order applying stricter veterinary tracking for warm-blooded animals entering Tennessee from infested regions. Field diagnostics teams have been deployed with specialized collection kits to verify suspected larval specimens immediately.
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Merck Animal Health Aligns Therapeutics: Reaffirming its commitments, Merck Animal Health highlighted the deployment of its cattle health innovations—such as EXZOLT CATTLE-CA1—as part of an industrywide collaboration to treat and control external parasitic vectors.
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Elanco Commits Support — Elanco Animal Health (NYSE: ELAN) issued a formal press release on June 4 reaffirming its portfolio of NWS treatments for livestock and companion animals. For livestock, products include Negasunt Powder (FDA EUA) and Tanidil (EPA Section 18 exemption) — both available exclusively through USDA APHIS and the National Veterinary Stockpile. For dogs and cats, Credelio Quattro-CA1 holds FDA conditional approval, and both Credelio and Credelio Cat carry FDA EUAs

