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 New World screwworm fly's larvae feed on live flesh, threatening livestock health and causing economic losses. US and Mexico are taking measures to control the outbreak and prevent its spread.

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.