Complex sentence: This infection triggered the most extensive food recall ever in U.S. history, involving, as of April 22,2009, at least 361 companies and 3,913 different products which were manufactured using PCA ingredients.
Split into simpler sentences: This infection triggered the most extensive food recall ever in US history. As of April 22,2009, it involved at least 361 companies and 3,913 different products manufactured using PCA ingredients.