The U.S. has again halted livestock imports from Mexico after the parasitic New World screwworm fly closer to the border.  Earlier this week, Mexico's national agriculture department reported a new case of New World Screwworm in Veracruz state,

The flesh-eating livestock pest New World screwworm has advanced closer to the U.S. border with Mexico, the U.S. Department of Agriculture said, prompting Washington to block imports of Mexican cattle just days after it allowed them to resume at a port of entry in Arizona.

America has stopped taking animals from northern Mexico. This is because of the New World Screwworm fly. This fly is harmful to animals. It lays eggs