LONDON - Fears about a suspected U.S. case of mad cow disease spread quickly abroad Wednesday, with 10 countries blocking the import of American beef after a cow in Washington state tested positive for the illness. Japan, the world's top importer of U.S. beef in terms of value, imposed an indefinite ban and planned to recall certain meat products already on the market, while South Korea halted customs inspections of American beef and suspended sales for meat already on supermarket shelves. Mexico, Russia, Brazil, Australia, Taiwan, Singapore, Thailand and Malaysia also banned the imports, as did the Chinese territory of...