U.S. Secretary of Agriculture Brooke Rollins has written to her Mexican counterpart to warn that imports of Mexican cattle could once again be restricted if Mexico doesn’t take additional steps to combat the New World screwworm (NWS). The United States paused imports of Mexican cattle last November after cases of screwworm — a flesh-eating pest — were identified in the southern state of Chiapas. More than 800 cases have been detected in animals in southern and southeastern Mexico since then.

The U.S. Department of Agriculture (USDA) is threatening to halt imports of cattle and bison from Mexico as the New World screwworm (NWS) continues to spread northward. Agriculture Secretary Brooke Rollins detailed U.S. demands in a letter sent to the Mexican government Saturday, April 26, and obtained by Fox News. New World screwworm larvae can be fatal when they burrow into and feast on the flesh of a living animal, effectively decimating herds. According to the USDA’s Animal and Plant Health Inspection Service (APHIS), NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, humans. The USDA eradicated NWS from the U.S. in 1966, however, the agency notes that “there is a constant risk of re-introduction into the United States.”

The US Department of Agriculture reportedly warned Mexico it will cease all live animal imports unless the country enforces stronger measures to stop a flesh-eating parasite from spreading northward. Agriculture Secretary Brooke Rollins issued a scathing letter to her Mexican counterpart Saturday threatening to block the importation of live cattle, bison and horses if the government fails to combat the spread of New World screwworm by April 30, Fox News reported. “We are now at a critical inflection point in our shared campaign against this pest, and I am very concerned about our collaboration,” the letter, obtained by Fox, said.

The USDA has set a firm deadline of April 30 for Mexico to address the growing crisis, or U.S. ports of entry will slam the door on key animal commodities. The New World screwworm, a flesh-eating fly whose larvae can decimate livestock populations, has been spreading rapidly from Central America.

Agriculture Secretary Brooke Rollins has sent Mexican Secretary of Agriculture and Rural Development Julio Berdegué Sacristán a letter telling him that if the Mexican government does not reach agreement by Wednesday to allow flights to...