Livestock Mexico hopes to quickly resolve New World Screwworm case halting cattle exports into US By Geralyn Wichers, Lizbeth Diaz, Sarah Morland November 28, 2024 Mexican President Claudia Sheinbaum said that Mexican and U.S. officials were in contact over a case of New World screwworm (NWS) detected late last week that caused the U.S. to halt imports of Mexican cattle.