E.coli outbreaks linked to Chipotle Mexican Grill restaurants that have sickened customers in several states appears to over, according to the Centers for Disease Control and Prevention (CDC).
The CDC said it was closing its investigation, though it never determined which food or ingredient was making people sick. Identifying the culprit in a restaurant that serves foods with several ingredients that are mixed or cooked with other ingredients and then used in multiple menu items can be a challenge even when conducting the most stringent epidemiologic studies, the CDC said.
E. coli is a bacteria that can cause severe stomach cramps and bouts of bloody diarrhea.
The Mexican restaurant chain said it has taken significant steps to improve the safety of its food, and will continue these efforts by closing all of its U.S. stores for part of the day on Feb. 8 in order to meet with employees to address changes in food safety procedures and answer employees’ questions.
Restaurants in the burrito chain have been hit with numerous food borne bacteria outbreaks in recent months, resulting in a staggering 30 percent drop in revenue in December.
Cases of E.coli linked to restaurants prompted the company in November to temporarily close 43 of its stores in Seattle and Portland. The restaurants were also linked to salmonella infections at a Minnesota restaurant, and norovirus infections that sickened at least 120 Boston College students.
The company ended 2015 by being slapped with a federal grand jury subpoena related to a criminal investigation by the U.S. attorney’s office for the Central District of California and the Food and Drug Administration (FDA). The focus of that investigation is on a norovirus outbreak last August at a Simi Valley Chipotle restaurant.