(Salem, OR)  --  Health officials say they haven't found the source of an E. coli outbreak that sickened more than 40 people in Oregon and Washington.  Forty-three Chipotle restaurants in both states were closed pending the investigation of the outbreak, and are preparing to reopen.  Officials initially suspected a raw vegetable was the likely source, but numerous lab tests have failed to turn up the bug.  The company has been given the go-ahead to reopen the locations, provided they remove all of the food, deep-clean the closed restaurants, and allow county food inspectors to check the locations.