NEW YORK — Chipotle warned Friday that an outbreak of E. coli linked to its restaurants is hurting sales and 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.

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

Of the 52 people infected, the CDC says 47 reported eating at a Chipotle restaurant the week before the illness started. The agency has not yet determined the ingredient that made people sick.

The CDC also said illnesses that started after Nov. 11 may not be reported yet.

People usually get sick from Shiga toxin-producing E. coli, the bacteria commonly associated with foodborne outbreaks, for two to eight days after swallowing the germ, according to the CDC. Most infected people get diarrhea and abdominal cramps.

Chipotle said Friday that store closures and bad publicity linked to the outbreak have slammed its sales. It said that if “recent sales trends continue,” it expects a decline in sales at established locations of 8 percent to 11 percent during the fourth quarter, and for fourth-quarter earnings per share to fall to between $2.45 and $2.85, from last year’s $3.84 per share. Analysts surveyed by FactSet had expected Chipotle to earn $4.12 per share for the December quarter.

The company said it was also pulling its comparable sales outlook for 2016 because of the recent sales trends and uncertainty related to the outbreak.

Shares of the company’s stock have dropped 25 percent since mid-October.