A 6-year-old child became acutely ill and developed fever, headache, and pain during swallowing. Three hours later, a bright-red fine punctate rash appeared on the hyperemic skin. The rash is more numerous on the lateral surfaces of the body and in the natural folds. The oropharyngeal mucosa has a clearly demarcated hyperemia. There is a purulent plaque on the tonsils. What disease has developed in the child?