Cases include those who have eaten beef since 1 March, but no supplier, distributor or brand of beef has been identified.
"Traceability investigations are underway to identify the source of prepared raw ground beef to grocery stores and restaurants where ill people reported the food," the CDC said.
Diseases began on March 1, and the infected were between 1 and 83 years old, with a mean age of 19 years.
"Diseases that occurred after March 26 may not be reported yet, as there is a time between the illness of a person with E. coli and the disease, which takes an average of two to three weeks." CDC said.
Symptoms include severe stomach cramps, diarrhea, and vomiting. They start on average three to four days after the bacteria are taken. Most people recover after five to seven days. The first symptoms reported by this outbreak started on March 2nd.
Consumers are urged to prevent the spread of E. coli by hand washing, to cook minced meat to an internal temperature of 160 degrees, and to keep uncooked foods away from raw beef to prevent cross-contamination.