Students in one northeast Iowa school district are getting an unexpected day off today. Officials in Tripoli decided to cancel classes and activities in an effort to keep a case of whooping cough from spreading. Superintendent Don Meier says there is only one confirmed case of the illness in the district, but he fears other students may have been exposed. Whooping cough starts like a cold with a runny nose, then progresses into uncontrollable coughing and sneezing. The illness is spread through the air, but can be treated with antibiotics. Tripoli is one of at least two northeast Iowa school districts dealing with cases of whooping cough. At least 21 students in Waterloo have also been diagnosed with the illness.