Livestock, News, Reuters U.S. not ready to lift Mexican cattle ban over screwworm, Agriculture Secretary Rollins says By Brendan O'Boyle, Cassandra Garrison, Reuters 11 hours ago The U.S. is not yet ready to reopen its border to Mexican cattle amid an outbreak of the flesh-eating New World screwworm parasite, Agriculture Secretary Brooke Rollins said, but she is pleased with Mexico’s efforts to contain the pest.