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. has closed its southern border again to livestock imports, saying a flesh-eating parasite has moved further north in Mexico than previously reported

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.