(RALEIGH) -- State health officials are now investigating 21 E. coli cases: nine of them confirmed - another 12 are suspected cases that are still being investigated.  State Epidemiologist Dr. Megan Davies said six counties have had residents affected.

"The breakdown of total cases is as follows: Durham County has one, Wake County 11, Johnston one, Franklin one, Cleveland County one, and Sampson County six," said Davies.

Dr. Davies said four children are still hospitalized.   She adds it is not clear yet what else the confirmed cases had in common besides attending the State Fair.

Health officials are closely monitoring the suspected cases.  Incubation time for E. coli means they could still develop into confirmed cases.