CHICAGO (FOX 32 News) - The CDC believes the E-coli outbreak that began at Chipotle restaurants is over.
But there is still mystery surrounding the outbreak.
The Wall Street Journal says its sources found no one has determined the original source of the outbreak.
When the Centers for Disease Control and Prevention declares an outbreak to be over, that means its investigation is closed, a CDC spokeswoman said.
The first E-coli case turned up in October, but no new cases have popped up in two months.
Next week, Chipotle plans to shut down all of its restaurants to hold a food safety meeting.
Along with e-coli, the chain has also had salmonella and norovirus outbreaks in the last few months.