Microbiology

A 4-year-old child at preschool begins displaying some signs of dehydration due to serious diarrhea and occasional vomiting. The child also has a fever and complains of abdominal discomfort. Thinking the child has a simple flu, the nurse sends the child home. Within 2 days a number of the children and one of the workers at the preschool begin experiencing abdominal pain, fever, some vomiting, and diarrhea. The victims did share cookies from a common plate, brought in by the mother of the child who first became ill.
On the basis of the circumstances and symptoms, what are the probable types of infection(s) involved?
What are the treatments, if any, and precautionary measures that may be taken to prevent the further spread of this viral infection?