Child is strep carrier, without symptoms. What do you suggest?

Nothing. See http://www.Pediatricweb.Com/madisonpeds/article.Asp?Articletype=9&articleid=851.
Strep carrier. If a child is a carrier of strep then he or she has to be treated with a full course of penicillin to eliminate the strep, because he can infect other children he is in contact with and the adults as well.