Scarlet fever outbreak in a primary and middle school in Germany: importance of case ascertainment and risk communication.

A cluster of 18 scarlet fever cases and large illness absenteeism (32%, 58/184) in a school prompted concern and further investigation. We conducted telephone interviews with parents to ascertain cases and better comprehend parents' views. We identified 19 cases, of which 13 reported scarlet fever diagnosis by a physician and only seven fulfilled the probable case definition. We concluded that the outbreak was far smaller than suspected and found that communication and reporting could be improved. Accurate information and communication is essential in an outbreak; the school's concern could have been alleviated sooner and response measures better targeted.