The nanny was held after the young child told his mother about the ordeal he went through - Representational image REUTERS/Suhaib Salem

An 18-year-old girl from Texas has been arrested and charged with sexual assault of a four-year-old boy. San Antonio police said Esmeralda Marie Medellin assaulted the child, whose name has not been revealed due to legal reasons, in March when she was babysitting him.

Medellin was arrested on 17 August and held at the Bexar County Magistrate's Office.

The nanny was reportedly held after the young child told his mother about the ordeal he went through. The boy said that Medellin not only physically abused him but also forced him to perform sexual acts on her.

DNA tests appear to confirm that the alleged sexual assault did take place, local reports said.

Police said in an affidavit presented to a court that they took swabs from both the child and the nanny. While the swabs taken from the babysitter proved inconclusive the ones from the child reportedly substantiated his claims.

Medellin is now charged with aggravated sexual assault of a child and held on a bond of $75,000 (£58,000).

According to Childhelp that provides statistics and facts on child abuse, today children are known to suffer from a hidden epidemic of child abuse and neglect and the US has one of the worst records among industrialised countries. It says that the country is losing an average of between four and seven children every day to child abuse and neglect.

The US Department of Justice website NSOPW says that approximately 60% of sexual abuse offenders are known to the child but are not family members, e.g., family friends, babysitters, child care providers and neighbours. About 30% of perpetrators of child sexual abuse are family members and only 10% of perpetrators are unknown to the child.