The E. coli outbreak connected to Chipotle restaurants has afflicted seven more people. The outbreak appears to have spread to three more states.

ABC News reports that 52 cases of E. coli have been reported in nine total states, to The Centers of Disease Control and Prevention. The new cases occurred in Illinois, Maryland, and Pennsylvania, with the most recent case appearing Nov. 13.

The outbreak was centralized in Oregon and Washington, beginning in October. Reports of additional cases followed in New York, California, Minnesota, and Ohio. The CDC anticipated, in late November, that cases beginning after Oct. 31 would continue to be reported.

In response to the outbreaks, Chipotle announced Friday that they would be tightening their standards for food safety. 47 of the 52 reported E. coli cases reported eating at a Chipotle location at least a week before experiencing symptoms. The ingredient responsible for the outbreaks has not yet been determined.

Chipotle has hired Seattle-based IEH Laboratories to assist in revamping its food safety procedures. The procedures will include the testing of all incoming produce and better food handling training for employees. The restaurant said they tested vegetables prior to the outbreak, but plans to test smaller batches, and larger samples.

According to Chipotle, none of the ingredients thought to be connected to the outbreak remain in the restaurants or in their supply. A spokesperson for Chipotle, Chris Arnold said that local produce used by Chipotle may not be able to meet the new standards. The local produce program is only a “relatively small percentage” of the supply, according to Arnold.  The program runs from June to October, in some parts of the U.S.