The best way to prevent diseases and illnesses in children is to teach them proper hygiene and self-care practices, and most importantly, ensure they are well-nourished and physically active. Many diseases, in children and adults alike, are the result of improper diet, leading to an imbalance that causes symptoms of sickness. In addition to this, it is vital for children to see a pediatrician on a regular basis, at least once a year, but in many cases more.