The U.S. has closed its southern border again to livestock imports, saying a flesh-eating parasite has moved further north in Mexico than previously reported. Mexico's president was critical Thursday,

The U.S. closes its southern border due to New World screwworm fly, a flesh-eating parasite that has decimated cattle ranches in the past.

The U.S. has shut its southern border to livestock imports again after a flesh-eating parasite was found further north in Mexico than previously reported, raising alarm among American agriculture officials.