Two workers at a northwest Iowa business mysteriously fell ill yesterday, and emergency workers dashed to the scene. The call went out after two M-C-I WorldCom workers in Sergeant Bluff, a Sioux City suburb, became dizzy and nauseous and appeared to be having seizures. Janet Flanagan of St. Luke’s Regional Medical Center in Sioux City says doctors, nurses, lab techs, social workers and a chaplain — about 30 people — rushed to the scene. She says they didn’t want to take any chances, so they sent the whole disaster team. Flanagan says when the initial call came in, they had expected to treat up to a dozen patients.No hazardous chemicals or materials were found at the scene and the two workers were released from the hospital.