(CNN) A multistate outbreak of E. coli has raised alarms and questions: As of Thursday, 72 people in five states have become ill, yet the cause of their infection remains unknown, the US Centers for Disease Control and Prevention reported Friday.

Symptoms of this bacterial infection, which usually begin about three or four days after consuming the bacteria, can include watery or bloody diarrhea, fever, abdominal cramps, nausea and vomiting.

Eight people involved in the mysterious outbreak have been hospitalized. No deaths have been reported. People started becoming ill March 2, and the patients range in age from 1 to 74 years old. Additional illnesses tied this outbreak may still be reported, the CDC said.

States reporting sick patients are Georgia (8 patients), Kentucky (36), Ohio (5), Tennessee (21) and Virginia (2).

Government scientists have not identified a food item, grocery store or restaurant chain as the source of these infections. The CDC, state health departments, the US Department of Agriculture's Food Safety and Inspection Service and the US Food and Drug Administration are investigating the outbreak.

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