Savannah Sanders’s first encounter with sex trafficking at the age of 16 was as a victim. But during the years since, she has tackled this shockingly prevalent problem as an educator, a mentor, a social work student and most recently an author. Her debut book “Sex Trafficking Prevention: A Trauma-Informed Approach for Parents and Professionals,” to be published by Unhooked Books on September 1, weaves her plight together with research on the U.S. sex trade and advice for everyday people to minimize children’s vulnerability.