Columbus health officials have identified cases of a bacterial illness in 30 day care centers, and say the number continues to rise daily.Shigella cases more than doubled in September in Franklin County and most are Columbus. There are 435 cases, compared with reported numbers in the teens in the past two years. The disease causes diarrhea and is easily spread when changing diapers, preparing food or cleaning up after bathroom breaks. Columbus Public Health Medical Director and Assistant Health Commissioner Doctor Mysheika Williams Roberts says officials are doing their best to identify ill children and offer day care centers preventative education. She says there are several contributing factors to the increase.