The North Central District Health Department said seven cases were confirmed.
All of them required the patients to be hospitalized, according to the department.
Health officials said five of them were mild cases, but two were a severe form of the bacterial infection known as Hemolytic Uremic Syndrome, or HUS.
They said the people with the mild cases have already been released, but one of the two with HUS remains in the hospital.
The source of the E. coli has not been found.