The CDC does not know yet if the more recent cases are tied to a larger outbreak that began at the end of October.
Five ill people were identified in Kansas, North Dakota and Oklahoma as part of the new investigation, on dates ranging from Nov.18 to Nov. 26, 2015. The new Illnesses are not included in the current case count, which is now at 53, the CDC report said.
On Oct. 31, an outbreak of E. coli was first linked to the chain, mostly in Washington and Oregon. Illnesses started on dates ranging from Oct. 19 to Nov. 13.
Twenty ill people were hospitalized during that outbreak, according to the CDC.
Chipotle announced it would revise its standards after reports of illnesses, with measures like high-resolution testing of ingredients, end of shelf-life testing of ingredients, continuous improvement in the supply system based on testing data and enhanced food safety training for team members.