Chipotle said Tuesday it will reopen all of the 43 outlets it closed in Washington and Oregon last month, although no one has been able to find the source of the outbreak of E. coli bacteria that sickened 42 people.
The outbreak appears to be over, the restaurant chain said.
"The restaurants are opening in the coming days with a fresh supply of all new ingredients," Chipotle said in a statement.
"The most recent reported date that a meal was served that may be linked with this incident is October 24. Incubation period for E. coli is typically three to four days after exposure, but may be as short as one day or as long as 10 days, according to the Centers for Disease Control and Prevention."
Chipotle said it has cleaned and sanitized all the affected outlets and replaced all the ingredients the chain uses. The popular restaurant chain says it is working with health officials to improve food handling processes and adding audits and inspections in all of its 2,000 restaurants.
"Eleven Chipotle restaurants, including six restaurants in Oregon and five in Washington, have been linked to this incident by the health departments. Out of an abundance of caution, Chipotle voluntarily closed 43 restaurants in Oregon and Washington," the restaurant chain said in its statement.
"No Chipotle locations outside of Oregon and Washington have been connected to this issue in any way."
The CDC says genetic fingerprinting showed at least 23 of the cases were linked.
"No cause has been established between this issue and any ingredient. Both Chipotle and health officials have been conducting food and environmental testing in Chipotle restaurants and distribution centers, but tests have not confirmed a link to any ingredient," the chain said.
The CDC has said Chipotle was taking the right actions in closing and cleaning its outlets.
This article first appeared on NBCNews.com.