Define Prevalence and Incidence for anorexia nervosa?

The disorder occurs most commonly in adolescent girls and young women, but adolescent boys and young men may be affected more rarely, as may children approaching puberty and older women up to the menopause. Although the prevalence/ incidence of the disorder is not known with certainty, about 0.5% to 1.0% adolescent girls and young women are reported to suffer from anorexia nervosa that meets the full criteria. Its incidence (appearance of new cases) among the 10-19 year old girls has definitely increased during the past decade. Anorexia nervosa appears to be more prevalent in industrialized countries that embrace and idealize a thin body type, but recent reviews suggest that it is increasing even in developing third world countries, such as ours.