The United States Centers for Disease Control and Prevention (CDC) announced on Monday that the two Shiga-toxin-producing Escheri coli outbreaks linked to Chipotle Mexican Grill, Inc. appear to be over. However, CDC officials were unable to determine the cause of the outbreak.

"The epidemiologic evidence collected during these investigations suggested that a common meal item or ingredient served at Chipotle Mexican Grill restaurants was a likely source of both outbreaks. The investigations did not identify a specific food or ingredient linked to illness in either outbreak," the CDC stated.

The initial outbreak happened last Oct. 19, 2015 with 55 total cases in 11 different states, but no deaths were recorded and only 21 were hospitalized. The most cases came from Washington with 27 followed by Oregon with 13.

The second outbreak on Dec. 1, 2015 affected five people in three states with just one victim being hospitalized. The Food and Drug Administration, Department of Agriculture's Food Safety and Inspection Service, and several public health officials from the affected states helped CDC in investigating the outbreaks.

"We are pleased that the CDC has concluded its investigation, and we have offered our full cooperation throughout. Over the past few months, we have taken significant steps to improve the safety of all of the food we serve, and we are confident that the changes we have made mean that every item on our menu is delicious and safe," Chipotle spokesman Chris Arnold said in a statement via CNBC News.

According to the Los Angeles Times, Chipotle temporarily closed 43 of its restaurants in Washington and Oregon before being reopened. A norovirus outbreak also happened in Boston from a Chipotle branch, which affected 141 students from Boston College.

Chipotle is planning to close all of its stores in the U.S. on Feb. 8 to hold a meeting with all their employees about the company's new food safety procedures. In a report by Forbes, the Denver-based company hired a consultant to design a stricter food safety program.

The outbreaks have caused Chipotle's stock and total sales to go down by 30 percent. However, the Los Angeles Times noted that the company's stock price increased after the news of CDC declaring that the E. Coli outbreak is over.

Although Chipotle's stock price increased on Monday, CNN reports that Wall Street is predicting a drop in its sales and profits for the first quarter of 2016. It is mentioned that Chipotle still have some competitions including McDonald's, Panera and rival Qdoba, but most importantly, they have to regain its customer's trust back.