A widening U.S. E. coli outbreak has slammed sales at Chipotle Mexican Grill Inc, the company said on Friday, hours after federal authorities reported that people in nine states have now contracted food poisoning.

Chipotle warned Friday that if recent trends continue, it expects earnings for the current quarter to come in way below analysts' prediction. Shares slid more than 7 percent in after-market trading.

The outbreak has expanded to nine states, with a total of 52 reported illnesses.

The Centers for Disease Control and Prevention had said Friday that seven additional people were sickened, including in three more states Illinois, Maryland and Pennsylvania. The most recent illness started on Nov. 13, it said.

The majority of the illnesses have been in Oregon and Washington, where cases were initially reported at the end of October. Additional cases were later reported in California, Minnesota, New York and Ohio.