A child cannot consent to any form of sexual activity, period. Child sexual abuse is a form of child abuse that includes sexual activity with a minor and does not always to include physical contact between a perpetrator and a child.  

"Human trafficking is modern-day slavery and involves the use of force, fraud, or coercion to obtain some type of labor or commercial sex act. Human trafficking is a hidden crime as victims rarely come forward to seek help because of language barriers, fear of the traffickers, and/or fear of law enforcement."

dhs.gov

"Physically abused children are at risk for later interpersonal problems involving aggressive behavior, and adolescents are at a much greater risk for substance abuse. In addition, symptoms of depression, emotional distress, and suicidal ideation are also common features of children and adolescents who have been physically abused. As many as one-third of children who experience physical abuse are also at risk to become abusive as adults." 

Being witness to violence or knowing the details of its occurrence can cause confusion and distortions in a child's mind. This can lead to feelings of depression, anxiety, suicidal, ideation, and somatic symptoms such as stomach aches, and headaches.