The federal agency that monitors public health says the outbreak of E. coli illness linked to Chipotle restaurants that sickened 60 people appears to be over.

The Centers for Disease Control and Prevention said Monday the most recent illness reported to the agency started on Dec. 1.

The source is still unknown, however.

In December, customers of a Chipotle restaurant in Chestnut Hill were sickened by the Norovirus. The restaurant was closed for several days as crews thoroughly cleaned the restaurant.

Chipotle Mexican Grill Inc. undertook an aggressive revamping of food preparation methods at its more than 1,900 locations. But the outbreak drove the company’s stock down by 26 percent over the past three months and it warned of a potentially sizeable hit to profits last month.

Shares are rebounding sharply in midday trading.

(Copyright (c) 2015 Sunbeam Television. The Associated Press contributed to this report. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

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