Children have a developing immune system and often they stay in close proximity in groups such as in places like classrooms, school buses or the day-care centers. This leads to a rapid transmission of the contagious diseases to the other children. This also explains why such diseases are particularly common in children. Common pediatric diseases that are contagious are mostly caused by bacterial or viral infections, transmitted through droplets of mucus or saliva, during sneezing or coughing. Su...