New World Screwworm Amidst Opening of Arizona Port

A confirmed New World screwworm case in the Mexican state of Sonora is raising questions just as the United States is scheduled to begin reopening a border crossing to Mexican cattle. Sonora confirmed its first case and activated emergency surveillance and containment measures. USDA previously announced the Douglas, Arizona, port would begin accepting livestock as of yesterday Aug. 24 as part of a phased reopening, ending a year long ban, provided Mexico continued meeting requirements under a joint action plan. The United States has restricted Mexican cattle movements while officials work to prevent the parasite from moving north. The Sonora discovery could complicate the reopening timeline. U.S. cattle producers are watching closely because imported feeder cattle affect supplies, while introduction of screwworm could create major economic losses for ranchers and livestock markets.