It is estimated that at any given time, up to 10% of the population will be carrying strep around in their pharynges. Perhaps up to 20% of pediatric patients. The difference between colonization and infection (detrimental colinization) is really adverse symptoms.  It is felt that it is unnecessary to treat assymptomatic carriers unless there is ARF in the community, a family history of ARF, documented family history of a symptomatic family member, or other related commorbidities.