CHICAGO: The flesh-eating livestock pest New World screwworm has advanced closer to the US border with Mexico, the US Department of Agriculture said, prompting Washington to block imports of Mexican cattle just days after it allowed them to resume at a port of entry in Arizona.

The U.S. Department of Agriculture has again halted imports of Mexican cattle into the United States due to the spread of the damaging livestock pest New World Screwworm in Mexico. Screwworms are parasitic flies whose females lay eggs in wounds on warm-blooded animals,

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